rfc9552.original   rfc9552.txt 
Inter-Domain Routing K. Talaulikar, Ed. Internet Engineering Task Force (IETF) K. Talaulikar, Ed.
Internet-Draft Cisco Systems Request for Comments: 9552 Cisco Systems
Obsoletes: 7752, 9029 (if approved) 25 August 2023 Obsoletes: 7752, 9029 December 2023
Intended status: Standards Track Category: Standards Track
Expires: 26 February 2024 ISSN: 2070-1721
Distribution of Link-State and Traffic Engineering Information Using BGP Distribution of Link-State and Traffic Engineering Information Using BGP
draft-ietf-idr-rfc7752bis-17
Abstract Abstract
In many environments, a component external to a network is called In many environments, a component external to a network is called
upon to perform computations based on the network topology and the upon to perform computations based on the network topology and the
current state of the connections within the network, including current state of the connections within the network, including
Traffic Engineering (TE) information. This is information typically Traffic Engineering (TE) information. This is information typically
distributed by IGP routing protocols within the network. distributed by IGP routing protocols within the network.
This document describes a mechanism by which link-state and TE This document describes a mechanism by which link-state and TE
information can be collected from networks and shared with external information can be collected from networks and shared with external
components using the BGP routing protocol. This is achieved using a components using the BGP routing protocol. This is achieved using a
BGP Network Layer Reachability Information (NLRI) encoding format. BGP Network Layer Reachability Information (NLRI) encoding format.
The mechanism applies to physical and virtual (e.g., tunnel) IGP The mechanism applies to physical and virtual (e.g., tunnel) IGP
links. The mechanism described is subject to policy control. links. The mechanism described is subject to policy control.
Applications of this technique include Application-Layer Traffic Applications of this technique include Application-Layer Traffic
Optimization (ALTO) servers and Path Computation Elements (PCEs). Optimization (ALTO) servers and Path Computation Elements (PCEs).
This document obsoletes RFC7752 by completely replacing that This document obsoletes RFC 7752 by completely replacing that
document. It makes some small changes and clarifications to the document. It makes some small changes and clarifications to the
previous specification. This document also obsoletes RFC9029 by previous specification. This document also obsoletes RFC 9029 by
incorporating the updates that it made to RFC7752. incorporating the updates that it made to RFC 7752.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is a product of the Internet Engineering Task Force
Task Force (IETF). Note that other groups may also distribute (IETF). It represents the consensus of the IETF community. It has
working documents as Internet-Drafts. The list of current Internet- received public review and has been approved for publication by the
Drafts is at https://datatracker.ietf.org/drafts/current/. Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Internet-Drafts are draft documents valid for a maximum of six months Information about the current status of this document, any errata,
and may be updated, replaced, or obsoleted by other documents at any and how to provide feedback on it may be obtained at
time. It is inappropriate to use Internet-Drafts as reference https://www.rfc-editor.org/info/rfc9552.
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This Internet-Draft will expire on 26 February 2024.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 6 1.1. Requirements Language
2. Motivation and Applicability . . . . . . . . . . . . . . . . 6 2. Motivation and Applicability
2.1. MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . 6 2.1. MPLS-TE with PCE
2.2. ALTO Server Network API . . . . . . . . . . . . . . . . . 7 2.2. ALTO Server Network API
3. BGP Speaker Roles for BGP-LS . . . . . . . . . . . . . . . . 8 3. BGP Speaker Roles for BGP-LS
4. Advertising IGP Information into BGP-LS . . . . . . . . . . . 10 4. Advertising IGP Information into BGP-LS
5. Carrying Link-State Information in BGP . . . . . . . . . . . 10 5. Carrying Link-State Information in BGP
5.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . 11 5.1. TLV Format
5.2. The Link-State NLRI . . . . . . . . . . . . . . . . . . . 12 5.2. The Link-State NLRI
5.2.1. Node Descriptors . . . . . . . . . . . . . . . . . . 16 5.2.1. Node Descriptors
5.2.2. Link Descriptors . . . . . . . . . . . . . . . . . . 20 5.2.2. Link Descriptors
5.2.3. Prefix Descriptors . . . . . . . . . . . . . . . . . 24 5.2.3. Prefix Descriptors
5.3. The BGP-LS Attribute . . . . . . . . . . . . . . . . . . 26 5.3. The BGP-LS Attribute
5.3.1. Node Attribute TLVs . . . . . . . . . . . . . . . . . 27 5.3.1. Node Attribute TLVs
5.3.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . 31 5.3.2. Link Attribute TLVs
5.3.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . 36 5.3.3. Prefix Attribute TLVs
5.4. Private Use . . . . . . . . . . . . . . . . . . . . . . . 41 5.4. Private Use
5.5. BGP Next-Hop Information . . . . . . . . . . . . . . . . 41 5.5. BGP Next-Hop Information
5.6. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . 42 5.6. Inter-AS Links
5.7. OSPF Virtual Links and Sham Links . . . . . . . . . . . . 42 5.7. OSPF Virtual Links and Sham Links
5.8. OSPFv2 Type 4 Summary LSA & OSPFv3 Inter-Area Router 5.8. OSPFv2 Type 4 Summary-LSA & OSPFv3 Inter-Area-Router-LSA
LSA . . . . . . . . . . . . . . . . . . . . . . . . . . 42 5.9. Handling of Unreachable IGP Nodes
5.9. Handling of Unreachable IGP Nodes . . . . . . . . . . . . 43 5.10. Router-ID Anchoring Example: ISO Pseudonode
5.10. Router-ID Anchoring Example: ISO Pseudonode . . . . . . . 44 5.11. Router-ID Anchoring Example: OSPF Pseudonode
5.11. Router-ID Anchoring Example: OSPF Pseudonode . . . . . . 45 5.12. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration
5.12. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration . 46 6. Link to Path Aggregation
6. Link to Path Aggregation . . . . . . . . . . . . . . . . . . 47 6.1. Example: No Link Aggregation
6.1. Example: No Link Aggregation . . . . . . . . . . . . . . 47 6.2. Example: ASBR to ASBR Path Aggregation
6.2. Example: ASBR to ASBR Path Aggregation . . . . . . . . . 48 6.3. Example: Multi-AS Path Aggregation
6.3. Example: Multi-AS Path Aggregation . . . . . . . . . . . 48 7. IANA Considerations
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49 7.1. BGP-LS Registries
7.1. BGP-LS Registries . . . . . . . . . . . . . . . . . . . . 49 7.1.1. BGP-LS NLRI Types Registry
7.1.1. BGP-LS NLRI Types Registry . . . . . . . . . . . . . 49 7.1.2. BGP-LS Protocol-IDs Registry
7.1.2. BGP-LS Protocol-IDs Registry . . . . . . . . . . . . 50 7.1.3. BGP-LS Well-Known Instance-IDs Registry
7.1.3. BGP-LS Well-Known Instance-IDs Registry . . . . . . . 51 7.1.4. BGP-LS Node Flags Registry
7.1.4. BGP-LS Node Flags Registry . . . . . . . . . . . . . 51 7.1.5. BGP-LS MPLS Protocol Mask Registry
7.1.5. BGP-LS MPLS Protocol Mask Registry . . . . . . . . . 52 7.1.6. BGP-LS IGP Prefix Flags Registry
7.1.6. BGP-LS IGP Prefix Flags Registry . . . . . . . . . . 53 7.1.7. BGP-LS TLVs Registry
7.1.7. BGP-LS TLVs Registry . . . . . . . . . . . . . . . . 53 7.2. Guidance for Designated Experts
7.2. Guidance for Designated Experts . . . . . . . . . . . . . 54 8. Manageability Considerations
8. Manageability Considerations . . . . . . . . . . . . . . . . 55 8.1. Operational Considerations
8.1. Operational Considerations . . . . . . . . . . . . . . . 55 8.1.1. Operations
8.1.1. Operations . . . . . . . . . . . . . . . . . . . . . 55 8.1.2. Installation and Initial Setup
8.1.2. Installation and Initial Setup . . . . . . . . . . . 56 8.1.3. Migration Path
8.1.3. Migration Path . . . . . . . . . . . . . . . . . . . 56
8.1.4. Requirements for Other Protocols and Functional 8.1.4. Requirements for Other Protocols and Functional
Components . . . . . . . . . . . . . . . . . . . . . 56 Components
8.1.5. Impact on Network Operation . . . . . . . . . . . . . 56 8.1.5. Impact on Network Operation
8.1.6. Verifying Correct Operation . . . . . . . . . . . . . 57 8.1.6. Verifying Correct Operation
8.2. Management Considerations . . . . . . . . . . . . . . . . 57 8.2. Management Considerations
8.2.1. Management Information . . . . . . . . . . . . . . . 57 8.2.1. Management Information
8.2.2. Fault Management . . . . . . . . . . . . . . . . . . 57 8.2.2. Fault Management
8.2.3. Configuration Management . . . . . . . . . . . . . . 59 8.2.3. Configuration Management
8.2.4. Accounting Management . . . . . . . . . . . . . . . . 60 8.2.4. Accounting Management
8.2.5. Performance Management . . . . . . . . . . . . . . . 60 8.2.5. Performance Management
8.2.6. Security Management . . . . . . . . . . . . . . . . . 60 8.2.6. Security Management
9. TLV/Sub-TLV Code Points Summary . . . . . . . . . . . . . . . 61 9. TLV/Sub-TLV Code Points Summary
10. Security Considerations . . . . . . . . . . . . . . . . . . . 63 10. Security Considerations
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 64 11. References
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 64 11.1. Normative References
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 65 11.2. Informative References
13.1. Normative References . . . . . . . . . . . . . . . . . . 65 Appendix A. Changes from RFC 7752
13.2. Informative References . . . . . . . . . . . . . . . . . 68 Acknowledgements
Appendix A. Changes from RFC 7752 . . . . . . . . . . . . . . . 70 Contributors
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 72 Author's Address
1. Introduction 1. Introduction
The contents of a Link-State Database (LSDB) or of an IGP's Traffic The contents of a Link-State Database (LSDB) or of an IGP's Traffic
Engineering Database (TED) describe only the links and nodes within Engineering Database (TED) describe only the links and nodes within
an IGP area. Some applications, such as end-to-end Traffic an IGP area. Some applications, such as end-to-end Traffic
Engineering (TE), would benefit from visibility outside one area or Engineering (TE), would benefit from visibility outside one area or
Autonomous System (AS) to make better decisions. Autonomous System (AS) to make better decisions.
The IETF has defined the Path Computation Element (PCE) [RFC4655] as The IETF has defined the Path Computation Element (PCE) [RFC4655] as
a mechanism for achieving the computation of end-to-end TE paths that a mechanism for achieving the computation of end-to-end TE paths that
cross the visibility of more than one TED or that requires CPU- crosses the visibility of more than one TED or that requires CPU-
intensive or coordinated computations. The IETF has also defined the intensive or coordinated computations. The IETF has also defined the
ALTO server [RFC5693] as an entity that generates an abstracted ALTO server [RFC5693] as an entity that generates an abstracted
network topology and provides it to network-aware applications. network topology and provides it to network-aware applications.
Both a PCE and an ALTO server need to gather information about the Both a PCE and an ALTO server need to gather information about the
topologies and capabilities of the network to be able to fulfill topologies and capabilities of the network to be able to fulfill
their function. their function.
This document describes a mechanism by which link-state and TE This document describes a mechanism by which link-state and TE
information can be collected from networks and shared with external information can be collected from networks and shared with external
skipping to change at page 4, line 26 skipping to change at line 163
encoding format. The mechanism applies to physical and virtual encoding format. The mechanism applies to physical and virtual
(e.g., tunnel) links. The mechanism described is subject to policy (e.g., tunnel) links. The mechanism described is subject to policy
control. control.
A router maintains one or more databases for storing link-state A router maintains one or more databases for storing link-state
information about nodes and links in any given area. Link attributes information about nodes and links in any given area. Link attributes
stored in these databases include: local/remote IP addresses, local/ stored in these databases include: local/remote IP addresses, local/
remote interface identifiers, link IGP metric, link TE metric, link remote interface identifiers, link IGP metric, link TE metric, link
bandwidth, reservable bandwidth, per Class-of-Service (CoS) class bandwidth, reservable bandwidth, per Class-of-Service (CoS) class
reservation state, preemption, and Shared Risk Link Groups (SRLGs). reservation state, preemption, and Shared Risk Link Groups (SRLGs).
The router's BGP Link-State (BGP-LS) process can retrieve topology The router's BGP - Link State (BGP-LS) process can retrieve topology
from these LSDBs and distribute it to a consumer, either directly or from these LSDBs and distribute it to a consumer, either directly or
via a peer BGP speaker (typically a dedicated Route Reflector), using via a peer BGP Speaker (typically a dedicated route reflector), using
the encoding specified in this document. the encoding specified in this document.
An illustration of the collection of link-state and TE information An illustration of the collection of link-state and TE information
and its distribution to consumers is shown in Figure 1 below. and its distribution to consumers is shown in Figure 1 below.
+-----------+ +-----------+
| Consumer | | Consumer |
+-----------+ +-----------+
^ ^
| |
skipping to change at page 5, line 30 skipping to change at line 196
| BGP | | BGP | | BGP | | BGP | | BGP | | BGP |
| Speaker | | Speaker | . . . | Speaker | | Speaker | | Speaker | . . . | Speaker |
| R1 | | R2 | | Rn | | R1 | | R2 | | Rn |
+-----------+ +-----------+ +-----------+ +-----------+ +-----------+ +-----------+
^ ^ ^ ^ ^ ^
| | | | | |
IGP IGP IGP IGP IGP IGP
Figure 1: Collection of Link-State and TE Information Figure 1: Collection of Link-State and TE Information
A BGP speaker may apply a configurable policy to the information that A BGP Speaker may apply a configurable policy to the information that
it distributes. Thus, it may distribute the real physical topology it distributes. Thus, it may distribute the real physical topology
from the LSDB or the TED. Alternatively, it may create an abstracted from the LSDB or the TED. Alternatively, it may create an abstracted
topology, where virtual, aggregated nodes are connected by virtual topology, where virtual, aggregated nodes are connected by virtual
paths. Aggregated nodes can be created, for example, out of multiple paths. Aggregated nodes can be created, for example, out of multiple
routers in a Point of Presence (POP). Abstracted topology can also routers in a Point of Presence (POP). Abstracted topology can also
be a mix of physical and virtual nodes and physical and virtual be a mix of physical and virtual nodes and physical and virtual
links. Furthermore, the BGP speaker can apply policy to determine links. Furthermore, the BGP Speaker can apply policy to determine
when information is updated to the consumer so that there is a when information is updated to the consumer so that there is a
reduction in information flow from the network to the consumers. reduction in information flow from the network to the consumers.
Mechanisms through which topologies can be aggregated or virtualized Mechanisms through which topologies can be aggregated or virtualized
are outside the scope of this document. are outside the scope of this document.
This document focuses on the specifications related to the This document focuses on the specifications related to the
origination of IGP-derived information and their propagation via BGP- origination of IGP-derived information and their propagation via BGP-
LS. It also describes the advertisement into BGP-LS of information, LS. It also describes the advertisement into BGP-LS of information,
either configured or derived, that is local to a node. In general, either configured or derived, that is local to a node. In general,
the procedures in this document form part of the base BGP-LS protocol the procedures in this document form part of the base BGP-LS protocol
skipping to change at page 6, line 13 skipping to change at line 225
introduced into BGP-LS. introduced into BGP-LS.
This document obsoletes [RFC7752] by completely replacing that This document obsoletes [RFC7752] by completely replacing that
document. It makes some small changes and clarifications to the document. It makes some small changes and clarifications to the
previous specification as documented in Appendix A. previous specification as documented in Appendix A.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Motivation and Applicability 2. Motivation and Applicability
This section describes use cases from which the requirements can be This section describes use cases from which the requirements can be
derived. derived.
2.1. MPLS-TE with PCE 2.1. MPLS-TE with PCE
As described in [RFC4655], a PCE can be used to compute MPLS-TE paths As described in [RFC4655], a PCE can be used to compute MPLS-TE paths
skipping to change at page 6, line 44 skipping to change at line 256
then its own TED lacks visibility of the complete topology. That then its own TED lacks visibility of the complete topology. That
means that the router cannot determine the end-to-end path and means that the router cannot determine the end-to-end path and
cannot even select the right exit router (Area Border Router cannot even select the right exit router (Area Border Router
(ABR)) for an optimal path. This is an issue for large-scale (ABR)) for an optimal path. This is an issue for large-scale
networks that need to segment their core networks into distinct networks that need to segment their core networks into distinct
areas but still want to take advantage of MPLS-TE. areas but still want to take advantage of MPLS-TE.
Previous solutions used per-domain path computation [RFC5152]. The Previous solutions used per-domain path computation [RFC5152]. The
source router could only compute the path for the first area because source router could only compute the path for the first area because
the router only has full topological visibility for the first area the router only has full topological visibility for the first area
along the path, but not for subsequent areas. Per-domain path along the path but not for subsequent areas. Per-domain path
computation uses a technique called "loose-hop-expansion" [RFC3209] computation selects the exit ABR and other ABRs or AS Border Routers
and selects the exit ABR and other ABRs or AS Border Routers (ASBRs) (ASBRs) as loose-hops [RFC3209] and using the IGP-computed shortest
using the IGP-computed shortest path topology for the remainder of path topology for the remainder of the path. This may lead to
the path. This may lead to suboptimal paths, makes alternate/back-up suboptimal paths, makes alternate/back-up path computation hard, and
path computation hard, and might result in no TE path being found might result in no TE path being found when one does exist.
when one does exist.
The PCE presents a computation server that may have visibility into The PCE presents a computation server that may have visibility into
more than one IGP area or AS, or may cooperate with other PCEs to more than one IGP area or AS or may cooperate with other PCEs to
perform distributed path computation. The PCE needs access to the perform distributed path computation. The PCE needs access to the
TED for the area(s) it serves, but [RFC4655] does not describe how TED for the area(s) it serves, but [RFC4655] does not describe how
this is achieved. Many implementations make the PCE a passive this is achieved. Many implementations make the PCE a passive
participant in the IGP so that it can learn the latest state of the participant in the IGP so that it can learn the latest state of the
network, but this may be sub-optimal when the network is subject to a network, but this may be suboptimal when the network is subject to a
high degree of churn or when the PCE is responsible for multiple high degree of churn or when the PCE is responsible for multiple
areas. areas.
The following figure shows how a PCE can get its TED information The following figure shows how a PCE can get its TED information
using the mechanism described in this document. using the mechanism described in this document.
+----------+ +---------+ +----------+ +---------+
| ----- | | BGP | | ----- | | BGP |
| | TED |<-+-------------------------->| Speaker | | | TED |<-+-------------------------->| Speaker |
| ----- | TED synchronization | | | ----- | TED synchronization | |
skipping to change at page 7, line 52 skipping to change at line 310
to configurable policy, and distributed to the PCE as necessary. to configurable policy, and distributed to the PCE as necessary.
2.2. ALTO Server Network API 2.2. ALTO Server Network API
An ALTO server [RFC5693] is an entity that generates an abstracted An ALTO server [RFC5693] is an entity that generates an abstracted
network topology and provides it to network-aware applications over a network topology and provides it to network-aware applications over a
web-service-based API. Example applications are peer-to-peer (P2P) web-service-based API. Example applications are peer-to-peer (P2P)
clients or trackers, or Content Distribution Networks (CDNs). The clients or trackers, or Content Distribution Networks (CDNs). The
abstracted network topology comes in the form of two maps: a Network abstracted network topology comes in the form of two maps: a Network
Map that specifies the allocation of prefixes to Partition Map that specifies the allocation of prefixes to Partition
Identifiers (PIDs), and a Cost Map that specifies the cost between Identifiers (PIDs) and a Cost Map that specifies the cost between
PIDs listed in the Network Map. For more details, see [RFC7285]. PIDs listed in the Network Map. For more details, see [RFC7285].
ALTO abstract network topologies can be auto-generated from the ALTO abstract network topologies can be auto-generated from the
physical topology of the underlying network. The generation would physical topology of the underlying network. The generation would
typically be based on policies and rules set by the operator. Both typically be based on policies and rules set by the operator. Both
prefix and TE data are required: prefix data is required to generate prefix and TE data are required: prefix data is required to generate
ALTO Network Maps and TE (topology) data is required to generate ALTO ALTO Network Maps and TE (topology) data is required to generate ALTO
Cost Maps. Prefix data is carried and originated in BGP, and TE data Cost Maps. Prefix data is carried and originated in BGP, and TE data
is originated and carried in an IGP. The mechanism defined in this is originated and carried in an IGP. The mechanism defined in this
document provides a single interface through which an ALTO server can document provides a single interface through which an ALTO server can
retrieve all the necessary prefixes and network topology data from retrieve all the necessary prefixes and network topology data from
the underlying network. Note that an ALTO server can use other the underlying network. Note that an ALTO server can use other
mechanisms to get network data, for example, peering with multiple mechanisms to get network data, for example, peering with multiple
IGP and BGP speakers. IGP and BGP Speakers.
The following figure shows how an ALTO server can get network The following figure shows how an ALTO server can get network
topology information from the underlying network using the mechanism topology information from the underlying network using the mechanism
described in this document. described in this document.
+--------+ +--------+
| Client |<--+ | Client |<--+
+--------+ | +--------+ |
| ALTO +--------+ Topology +---------+ | ALTO +--------+ Topology +---------+
+--------+ | Protocol | ALTO | Sync Mechanism | BGP | +--------+ | Protocol | ALTO | Sync Mechanism | BGP |
skipping to change at page 8, line 39 skipping to change at line 346
+--------+ | | | | | +--------+ | | | | |
| +--------+ +---------+ | +--------+ +---------+
+--------+ | +--------+ |
| Client |<--+ | Client |<--+
+--------+ +--------+
Figure 3: ALTO Server Using Network Topology Information Figure 3: ALTO Server Using Network Topology Information
3. BGP Speaker Roles for BGP-LS 3. BGP Speaker Roles for BGP-LS
In the illustration shown in Figure 1, the BGP Speakers can be seen In Figure 1, the BGP Speakers can be seen playing different roles in
playing different roles in the distribution of information using BGP- the distribution of information using BGP-LS. This section
LS. This section introduces terms that explain the different roles introduces terms that explain the different roles of the BGP Speakers
of the BGP Speakers which are then used through the rest of this that are then used throughout the rest of this document.
document.
* BGP-LS Producer: The term BGP-LS Producer refers to a BGP Speaker BGP-LS Producer: The term BGP-LS Producer refers to a BGP Speaker
that is originating link-state information into BGP. The BGP that is originating link-state information into BGP. BGP Speakers
Speakers R1, R2, ... Rn, originate link-state information from R1, R2, ... Rn originate link-state information from their
their underlying link-state IGP protocols into BGP-LS. If R1 and underlying link-state IGP protocols into BGP-LS. If R1 and R2 are
R2 are in the same IGP flooding domain, then they would ordinarily in the same IGP flooding domain, then they would ordinarily
originate the same link-state information into BGP-LS. R1 may originate the same link-state information into BGP-LS. R1 may
also originate information from sources other than IGP, e.g. its also originate information from sources other than IGP, e.g., its
local node information. local node information.
* BGP-LS Consumer: The term BGP-LS Consumer refers to a consumer BGP-LS Consumer: The term BGP-LS Consumer refers to a consumer
application/process and not a BGP Speaker. The BGP Speakers RR1 application/process and not a BGP Speaker. BGP Speakers RR1 and
and Rn are handing off the BGP-LS information that they have Rn are handing off the BGP-LS information that they have collected
collected to a consumer application. The BGP protocol to a consumer application. The BGP protocol implementation and
implementation and the consumer application may be on the same or the consumer application may be on the same or different nodes.
different nodes. This document only covers the BGP This document only covers the BGP implementation. The consumer
implementation. The consumer application and the design of the application and the design of the interface between BGP and the
interface between BGP and the consumer application may be consumer application may be implementation specific and are
implementation specific and are outside the scope of this outside the scope of this document. The communication of
document. The communication of information MUST be unidirectional information MUST be unidirectional (i.e., from a BGP Speaker to
(i.e., from a BGP Speaker to the BGP-LS Consumer application) and the BGP-LS Consumer application), and a BGP-LS Consumer MUST NOT
a BGP-LS Consumer MUST NOT be able to send information to a BGP be able to send information to a BGP Speaker for origination into
Speaker for origination into BGP-LS. BGP-LS.
* BGP-LS Propagator: The term BGP-LS Propagator refers to a BGP BGP-LS Propagator: The term BGP-LS Propagator refers to a BGP
Speaker that is performing BGP protocol processing on the link- Speaker that is performing BGP protocol processing on the link-
state information. The BGP Speaker RRm propagates the BGP-LS state information. BGP Speaker RRm propagates the BGP-LS
information between the BGP Speaker Rn and the BGP Speaker RR1. information between BGP Speaker Rn and BGP Speaker RR1. The BGP
The BGP implementation on RRm is propagating BGP-LS information. implementation on RRm is propagating BGP-LS information. It
It performs handling of BGP-LS UPDATE messages and performs the performs handling of BGP-LS UPDATE messages and performs the BGP
BGP Decision Process as part of deciding what information is to be Decision Process as part of deciding what information is to be
propagated. Similarly, the BGP Speaker RR1 is receiving BGP-LS propagated. Similarly, BGP Speaker RR1 is receiving BGP-LS
information from R1, R2, and RRm and propagating the information information from R1, R2, and RRm and propagating the information
to the BGP-LS Consumer after performing BGP Decision Process. to the BGP-LS Consumer after performing BGP Decision Process.
The above roles are not mutually exclusive. The same BGP Speaker may The above roles are not mutually exclusive. The same BGP Speaker may
be the BGP-LS Producer for some link-state information and BGP-LS be the BGP-LS Producer for some link-state information and BGP-LS
Propagator for some other link-state information while also providing Propagator for some other link-state information while also providing
this information to a BGP-LS Consumer. this information to a BGP-LS Consumer.
The rest of this document refers to the role when describing The rest of this document refers to the role when describing
procedures that are specific to that role. When the role is not procedures that are specific to that role. When the role is not
specified, then the said procedure applies to all BGP Speakers. specified, then the said procedure applies to all BGP Speakers.
4. Advertising IGP Information into BGP-LS 4. Advertising IGP Information into BGP-LS
The origination and propagation of IGP link-state information via BGP The origination and propagation of IGP link-state information via BGP
needs to provide a consistent and accurate view of the topology of needs to provide a consistent and accurate view of the topology of
the IGP domain. BGP-LS provides an abstraction of the IGP specifics the IGP domain. BGP-LS provides an abstraction of the IGP specifics,
and BGP-LS Consumers may be varied types of applications. and BGP-LS Consumers may be varied types of applications.
The link-state information advertised in BGP-LS from the IGPs is The link-state information advertised in BGP-LS from the IGPs is
derived from the IGP LSDB built using the OSPF Link State derived from the IGP LSDB built using the OSPF Link-State
Advertisements (LSAs) or the IS-IS Link State Packets (LSPs). Advertisements (LSAs) or the IS-IS Link-State Packets (LSPs).
However, it does not serve as a verbatim reflection of the However, it does not serve as a verbatim reflection of the
originating router's LSDB. It does not include the LSA/LSP sequence originating router's LSDB. It does not include the LSA/LSP sequence
number information since a single link-state object may be put number information since a single link-state object may be put
together with information that is coming from multiple LSAs/LSPs. together with information that is coming from multiple LSAs/LSPs.
Also, not all of the information carried in LSAs/LSPs may be required Also, not all of the information carried in LSAs/LSPs may be required
or suitable for advertisement via BGP-LS (e.g., ASBR reachability in or suitable for advertisement via BGP-LS (e.g., ASBR reachability in
OSPF, OSPF virtual links, link-local scoped information, etc.). The OSPF, OSPF virtual links, link-local-scoped information, etc.). The
LSAs/LSPs that are purged or max-aged are not included in the BGP-LS LSAs/LSPs that are purged or aged out are not included in the BGP-LS
advertisement even though they may be present in the LSDB (e.g., for advertisement even though they may be present in the LSDB (e.g., for
the IGP flooding purposes). The information from the LSAs/LSPs that the IGP flooding purposes). The information from the LSAs/LSPs that
is invalid or malformed or that which needs to be ignored per the is invalid or malformed or that which needs to be ignored per the
respective IGP protocol specifications are also not included in the respective IGP protocol specifications are also not included in the
BGP-LS advertisement. BGP-LS advertisement.
The details of the interface between IGPs and BGP for the The details of the interface between IGPs and BGP for the
advertisement of link-state information are outside the scope of this advertisement of link-state information are outside the scope of this
document. In some cases, the information derived from IGP processing document. In some cases, the information derived from IGP processing
(e.g., combination of link-state object from across multiple LSAs/ (e.g., combination of link-state object from across multiple LSAs/
LSPs, leveraging reachability and two-way connectivity checks, etc.) LSPs, leveraging reachability and two-way connectivity checks, etc.)
is required for advertisement of link-state information into BGP-LS. is required for the advertisement of link-state information into BGP-
LS.
5. Carrying Link-State Information in BGP 5. Carrying Link-State Information in BGP
The link-state information is carried in BGP UPDATE messages as: (1) The link-state information is carried in BGP UPDATE messages as: (1)
BGP NLRI information carried within MP_REACH_NLRI and MP_UNREACH_NLRI BGP NLRI information carried within MP_REACH_NLRI and MP_UNREACH_NLRI
attributes that describes link, node, or prefix object, and (2) a BGP attributes that describes link, node, or prefix objects and (2) a BGP
path attribute (BGP-LS Attribute) that carries properties of the path attribute (BGP-LS Attribute) that carries properties of the
link, node, or prefix objects such as the link and prefix metric or link, node, or prefix objects such as the link and prefix metric,
auxiliary Router-IDs of nodes, etc. auxiliary Router-IDs of nodes, etc.
It is desirable to keep the dependencies on the protocol source of It is desirable to keep the dependencies on the protocol source of
this attribute to a minimum and represent any content in an IGP- this attribute to a minimum and represent any content in an IGP-
neutral way, such that applications that want to learn about a link- neutral way, such that applications that want to learn about a link-
state topology do not need to know about any OSPF or IS-IS protocol state topology do not need to know about any OSPF or IS-IS protocol
specifics. specifics.
This section mainly describes the procedures for a BGP-LS Producer to This section mainly describes the procedures for a BGP-LS Producer to
originate link-state information into BGP-LS. originate link-state information into BGP-LS.
skipping to change at page 11, line 29 skipping to change at line 468
Figure 4: TLV Format Figure 4: TLV Format
The Length field defines the length of the value portion in octets The Length field defines the length of the value portion in octets
(thus, a TLV with no value portion would have a length of zero). The (thus, a TLV with no value portion would have a length of zero). The
TLV is not padded to 4-octet alignment. Unknown and unsupported TLV is not padded to 4-octet alignment. Unknown and unsupported
types MUST be preserved and propagated within both the NLRI and the types MUST be preserved and propagated within both the NLRI and the
BGP-LS Attribute. The presence of unknown or unexpected TLVs MUST BGP-LS Attribute. The presence of unknown or unexpected TLVs MUST
NOT result in the NLRI or the BGP-LS Attribute being considered NOT result in the NLRI or the BGP-LS Attribute being considered
malformed. An example of an unexpected TLV is when a TLV is received malformed. An example of an unexpected TLV is when a TLV is received
along with an update for a link state object other than the one that along with an update for a link-state object other than the one that
the TLV is specified as associated with. the TLV is specified as associated with.
To compare NLRIs with unknown TLVs, all TLVs within the NLRI MUST be To compare NLRIs with unknown TLVs, all TLVs within the NLRI MUST be
ordered in ascending order by TLV Type. If there are multiple TLVs ordered in ascending order by TLV Type. If there are multiple TLVs
of the same type within a single NLRI, then the TLVs sharing the same of the same type within a single NLRI, then the TLVs sharing the same
type MUST be first in ascending order based on the length field type MUST be first in ascending order based on the Length field
followed by ascending order based on the value field. Comparison of followed by ascending order based on the Value field. Comparison of
the value fields is performed by treating the entire field as opaque the Value fields is performed by treating the entire field as opaque
binary data and ordered lexicographically (i.e., treating each byte binary data and ordered lexicographically (i.e., treating each byte
of binary data as a symbol to compare, with the symbols ordered by of binary data as a symbol to compare, with the symbols ordered by
their numerical value). NLRIs having TLVs which do not follow the their numerical value). NLRIs having TLVs that do not follow the
above ordering rules MUST be considered as malformed by a BGP-LS above ordering rules MUST be considered as malformed by a BGP-LS
Propagator. This insistence on canonical ordering ensures that Propagator. This insistence on canonical ordering ensures that
multiple variant copies of the same NLRI from multiple BGP-LS multiple variant copies of the same NLRI from multiple BGP-LS
Producers and the ambiguity arising therefrom is prevented. Producers and the ambiguity arising therefrom is prevented.
For both the NLRI and BGP-LS Attribute parts, all TLVs are considered For both the NLRI and BGP-LS Attribute parts, all TLVs are considered
as optional except where explicitly specified as mandatory or as optional except where explicitly specified as mandatory or
required in specific conditions. required in specific conditions.
The TLVs within the BGP-LS Attribute SHOULD be ordered in ascending The TLVs within the BGP-LS Attribute SHOULD be ordered in ascending
order by TLV type. BGP-LS Attribute with unordered TLVs MUST NOT be order by TLV type. The BGP-LS Attribute with unordered TLVs MUST NOT
considered malformed. be considered malformed.
The origination of the same link-state information by multiple BGP-LS The origination of the same link-state information by multiple BGP-LS
Producers may result in differences and inconsistencies due to the Producers may result in differences and inconsistencies due to the
inclusion or exclusion of optional TLVs. Different optional TLVs in inclusion or exclusion of optional TLVs. Different optional TLVs in
the NLRI results in multiple NLRIs being generated for the same link- the NLRI results in multiple NLRIs being generated for the same link-
state object. Different optional TLVs in the BGP-LS Attribute may state object. Different optional TLVs in the BGP-LS Attribute may
result in the propagation of partial information. To address these result in the propagation of partial information. To address these
inconsistencies, the BGP-LS Consumer will need to recognize and merge inconsistencies, the BGP-LS Consumer will need to recognize and merge
the duplicate information, or to deal with missing information. The the duplicate information or deal with missing information. The
deployment of BGP-LS Producers that consistently originate the same deployment of BGP-LS Producers that consistently originate the same
set of optional TLVs is recommended to mitigate such situations. set of optional TLVs is recommended to mitigate such situations.
5.2. The Link-State NLRI 5.2. The Link-State NLRI
The MP_REACH_NLRI and MP_UNREACH_NLRI attributes are BGP's containers The MP_REACH_NLRI and MP_UNREACH_NLRI attributes are BGP's containers
for carrying opaque information. This specification defines three for carrying opaque information. This specification defines three
Link-State NLRI types that describe either a node, a link, or a Link-State NLRI types that describe either a node, a link, or a
prefix. prefix.
All non-VPN link, node, and prefix information SHALL be encoded using All non-VPN link, node, and prefix information SHALL be encoded using
AFI 16388 / SAFI 71. VPN link, node, and prefix information SHALL be AFI 16388 / SAFI 71. VPN link, node, and prefix information SHALL be
encoded using AFI 16388 / SAFI 72. encoded using AFI 16388 / SAFI 72.
For two BGP speakers to exchange Link-State NLRI, they MUST use BGP For two BGP Speakers to exchange Link-State NLRI, they MUST use BGP
Capabilities Advertisement to ensure that they are both capable of Capabilities Advertisement to ensure that they are both capable of
properly processing such NLRI. This is done as specified in properly processing such NLRI. This is done as specified in
[RFC4760], by using capability code 1 (multiprotocol BGP), with AFI [RFC4760] by using capability code 1 (multiprotocol BGP), with AFI
16388 / SAFI 71 for BGP-LS, and AFI 16388 / SAFI 72 for BGP-LS-VPN. 16388 / SAFI 71 for BGP-LS and AFI 16388 / SAFI 72 for BGP-LS-VPN.
New Link-State NLRI Types may be introduced in the future. Since New Link-State NLRI types may be introduced in the future. Since
supported NLRI type values within the address family are not supported NLRI type values within the address family are not
expressed in the Multiprotocol BGP (MP-BGP) capability [RFC4760], it expressed in the Multiprotocol BGP (MP-BGP) capability [RFC4760], it
is possible that a BGP speaker has advertised support for BGP-LS but is possible that a BGP Speaker has advertised support for BGP-LS but
does not support a particular Link-State NLRI type. To allow the does not support a particular Link-State NLRI type. To allow the
introduction of new Link-State NLRI types seamlessly in the future, introduction of new Link-State NLRI types seamlessly in the future
without the need for upgrading all BGP speakers in the propagation without the need for upgrading all BGP Speakers in the propagation
path (e.g., a route reflector), this document deviates from the path (e.g., a route reflector), this document deviates from the
default handling behavior specified by section 5.4 (paragraph 2) of default handling behavior specified by Section 5.4 (paragraph 2) of
[RFC7606] for Link-State address-family. An implementation MUST [RFC7606] for Link-State address family. An implementation MUST
handle unknown Link-State NLRI types as opaque objects and MUST handle unknown Link-State NLRI types as opaque objects and MUST
preserve and propagate them. preserve and propagate them.
The format of the Link-State NLRI is shown in the following figures. The format of the Link-State NLRI is shown in the following figures.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Type | Total NLRI Length | | NLRI Type | Total NLRI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 14, line 42 skipping to change at line 622
// Local Node Descriptors TLV (variable) // // Local Node Descriptors TLV (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Remote Node Descriptors TLV (variable) // // Remote Node Descriptors TLV (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Link Descriptors TLVs (variable) // // Link Descriptors TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: The Link NLRI Format Figure 8: The Link NLRI Format
The IPv4 and IPv6 Prefix NLRIs (NLRI Type = 3 and Type = 4) use the The IPv4 and IPv6 Prefix NLRIs (NLRI Type = 3 and Type = 4) use the
same format, as shown in the following figure. same format as shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| Protocol-ID | | Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | | Identifier |
+ (8 octets) + + (8 octets) +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 16, line 18 skipping to change at line 686
same IGP routing instance should have the same BGP-LS Instance-ID. same IGP routing instance should have the same BGP-LS Instance-ID.
NLRIs with different BGP-LS Instance-IDs are considered to be from NLRIs with different BGP-LS Instance-IDs are considered to be from
different IGP routing instances. different IGP routing instances.
To support multiple IGP instances, an implementation needs to support To support multiple IGP instances, an implementation needs to support
the configuration of unique BGP-LS Instance-IDs at the routing the configuration of unique BGP-LS Instance-IDs at the routing
protocol instance level. The BGP-LS Instance-ID 0 is RECOMMENDED to protocol instance level. The BGP-LS Instance-ID 0 is RECOMMENDED to
be used when there is only a single protocol instance in the network be used when there is only a single protocol instance in the network
where BGP-LS is operational. The network operator MUST assign the where BGP-LS is operational. The network operator MUST assign the
same BGP-LS Instance-IDs on all BGP-LS Producers within a given IGP same BGP-LS Instance-IDs on all BGP-LS Producers within a given IGP
domain. Unique BGP-LS Instance-ID MUST be assigned to routing domain. Unique BGP-LS Instance-IDs MUST be assigned to routing
protocol instances operating in different IGP domains. This can protocol instances operating in different IGP domains. This can
allow the BGP-LS Consumer to build an accurate segregated multi- allow the BGP-LS Consumer to build an accurate segregated multi-
domain topology based on the BGP-LS Instance-ID. domain topology based on the BGP-LS Instance-ID.
When the above-described semantics and recommendations are not When the above-described semantics and recommendations are not
followed, a BGP-LS Consumer may see more than one link-state objects followed, a BGP-LS Consumer may see more than one link-state object
for the same node, link, or prefix (each with a different BGP-LS for the same node, link, or prefix (each with a different BGP-LS
Instance-ID) when there are multiple BGP-LS Producers deployed. This Instance-ID) when there are multiple BGP-LS Producers deployed. This
may also result in the BGP-LS Consumers getting an inaccurate may also result in the BGP-LS Consumers getting an inaccurate
network-wide topology. network-wide topology.
Each Node Descriptor, Link Descriptor, and Prefix Descriptor consists Each Node Descriptor, Link Descriptor, and Prefix Descriptor consists
of one or more TLVs, as described in the following sections. These of one or more TLVs, as described in the following sections. These
Descriptor TLVs are applicable for the Node, Link, and Prefix NLRI Descriptor TLVs are applicable for the Node, Link, and Prefix NLRI
Types for the protocols that are listed in Table 2. Documents Types for the protocols that are listed in Table 2. Documents
extending BGP-LS specifications with new NLRI Types and/or protocols extending BGP-LS specifications with new NLRI Types and/or protocols
MUST specify the NLRI Descriptors for them. MUST specify the NLRI descriptors for them.
When adding, removing, or modifying a TLV/sub-TLV from a Link-State When adding, removing, or modifying a TLV/sub-TLV from a Link-State
NLRI, the BGP-LS Producer MUST withdraw the old NLRI by including it NLRI, the BGP-LS Producer MUST withdraw the old NLRI by including it
in the MP_UNREACH_NLRI. Not doing so can result in duplicate and in- in the MP_UNREACH_NLRI. Not doing so can result in duplicate and
consistent link-state objects hanging around in the BGP-LS table. inconsistent link-state objects hanging around in the BGP-LS table.
5.2.1. Node Descriptors 5.2.1. Node Descriptors
Each link is anchored by a pair of Router-IDs that are used by the Each link is anchored by a pair of Router-IDs that are used by the
underlying IGP, namely, a 48-bit ISO System-ID for IS-IS and a 32-bit underlying IGP, namely a 48-bit ISO System-ID for IS-IS and a 32-bit
Router-ID for OSPFv2 and OSPFv3. An IGP may use one or more Router-ID for OSPFv2 and OSPFv3. An IGP may use one or more
additional auxiliary Router-IDs, mainly for Traffic Engineering additional auxiliary Router-IDs, mainly for Traffic Engineering
purposes. For example, IS-IS may have one or more IPv4 and IPv6 TE purposes. For example, IS-IS may have one or more IPv4 and IPv6 TE
Router-IDs [RFC5305] [RFC6119]. When configured, these auxiliary TE Router-IDs [RFC5305] [RFC6119]. When configured, these auxiliary TE
Router-IDs (TLV 1028/1029) MUST be included in the node attribute Router-IDs (TLV 1028/1029) MUST be included in the node attribute
described in Section 5.3.1 and MAY be included in the link attribute described in Section 5.3.1 and MAY be included in the link attribute
described in Section 5.3.2. The advertisement of the TE Router-IDs described in Section 5.3.2. The advertisement of the TE Router-IDs
can help a BGP-LS Consumer to correlate multiple link-state objects can help a BGP-LS Consumer to correlate multiple link-state objects
(e.g. in different IGP instances or areas/levels) to the same node in (e.g., in different IGP instances or areas/levels) to the same node
the network. in the network.
It is desirable that the Router-ID assignments inside the Node It is desirable that the Router-ID assignments inside the Node
Descriptors are globally unique. However, there may be Router-ID Descriptors are globally unique. However, there may be Router-ID
spaces (e.g., ISO) where no global registry exists, or worse, Router- spaces (e.g., ISO) where no global registry exists, or worse, Router-
IDs have been allocated following the private-IP allocation described IDs have been allocated following the private-IP allocation described
in [RFC1918]. BGP-LS uses the Autonomous System (AS) Number to in [RFC1918]. BGP-LS uses the Autonomous System Number to
disambiguate the Router-IDs, as described in Section 5.2.1.1. disambiguate the Router-IDs, as described in Section 5.2.1.1.
5.2.1.1. Globally Unique Node/Link/Prefix Identifiers 5.2.1.1. Globally Unique Node/Link/Prefix Identifiers
One problem that needs to be addressed is the ability to identify an One problem that needs to be addressed is the ability to identify an
IGP node globally (by "globally", we mean within the BGP-LS database IGP node globally (by "globally", we mean within the BGP-LS database
collected by all BGP-LS speakers that talk to each other). This can collected by all BGP-LS Speakers that talk to each other). This can
be expressed through the following two requirements: be expressed through the following two requirements:
(A) The same node MUST NOT be represented by two keys (otherwise, (A) The same node MUST NOT be represented by two keys (otherwise,
one node will look like two nodes). one node will look like two nodes).
(B) Two different nodes MUST NOT be represented by the same key (B) Two different nodes MUST NOT be represented by the same key
(otherwise, two nodes will look like one node). (otherwise, two nodes will look like one node).
We define an "IGP domain" to be the set of nodes (hence, by extension We define an "IGP domain" to be the set of nodes (hence, by
links and prefixes) within which each node has a unique IGP extension, links and prefixes) within which each node has a unique
representation by using the combination of OSPF Area-ID, Router-ID, IGP representation by using the combination of OSPF Area-ID, Router-
Protocol-ID, Multi-Topology ID, and BGP-LS Instance-ID. The problem ID, Protocol-ID, Multi-Topology Identifier (MT-ID), and BGP-LS
is that BGP may receive node/link/prefix information from multiple Instance-ID. The problem is that BGP may receive node/link/prefix
independent "IGP domains", and we need to distinguish between them. information from multiple independent "IGP domains", and we need to
Moreover, we can't assume there is always one and only one IGP domain distinguish between them. Moreover, we can't assume there is always
per AS. During IGP transitions, it may happen that two redundant one and only one IGP domain per AS. During IGP transitions, it may
IGPs are in place. happen that two redundant IGPs are in place.
Furthermore, in deployments where BGP-LS is used to advertise Furthermore, in deployments where BGP-LS is used to advertise
topology from multiple-ASes, the AS Number is used to distinguish topology from multiple ASes, the Autonomous System Number (ASN) is
topology information reported from different ASes. used to distinguish topology information reported from different
ASes.
The BGP-LS Instance-ID carried in the Identifier field as described The BGP-LS Instance-ID carried in the Identifier field, as described
earlier along with a set of sub-TLVs described in Section 5.2.1.4, earlier along with a set of sub-TLVs described in Section 5.2.1.4,
allows specification of a flexible key for any given node/link allows specification of a flexible key for any given node/link
information such that the global uniqueness of the NLRI is ensured. information such that the global uniqueness of the NLRI is ensured.
Since the BGP-LS Instance-ID is operator assigned, its allocation Since the BGP-LS Instance-ID is operator assigned, its allocation
scheme can ensure that each IGP domain is uniquely identified even scheme can ensure that each IGP domain is uniquely identified even
across a multi-AS network. across a multi-AS network.
5.2.1.2. Local Node Descriptors 5.2.1.2. Local Node Descriptors
The Local Node Descriptors TLV contains Node Descriptors for the node The Local Node Descriptors TLV contains Node Descriptors for the node
anchoring the local end of the link. This is a mandatory TLV in all anchoring the local end of the link. This is a mandatory TLV in all
three types of NLRIs (node, link, and prefix). The Type is 256. The three types of NLRIs (node, link, and prefix). The Type is 256. The
length of this TLV is variable. The value contains one or more Node length of this TLV is variable. The value contains one or more Node
Descriptor Sub-TLVs defined in Section 5.2.1.4. Descriptor sub-TLVs defined in Section 5.2.1.4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Node Descriptor Sub-TLVs (variable) // // Node Descriptor Sub-TLVs (variable) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Local Node Descriptors TLV Format Figure 10: Local Node Descriptors TLV Format
5.2.1.3. Remote Node Descriptors 5.2.1.3. Remote Node Descriptors
The Remote Node Descriptors TLV contains Node Descriptors for the The Remote Node Descriptors TLV contains Node Descriptors for the
node anchoring the remote end of the link. This is a mandatory TLV node anchoring the remote end of the link. This is a mandatory TLV
for Link NLRIs. The type is 257. The length of this TLV is for Link NLRIs. The Type is 257. The length of this TLV is
variable. The value contains one or more Node Descriptor Sub-TLVs variable. The value contains one or more Node Descriptor sub-TLVs
defined in Section 5.2.1.4. defined in Section 5.2.1.4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Node Descriptor Sub-TLVs (variable) // // Node Descriptor Sub-TLVs (variable) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Remote Node Descriptors TLV Format Figure 11: Remote Node Descriptors TLV Format
5.2.1.4. Node Descriptor Sub-TLVs 5.2.1.4. Node Descriptor Sub-TLVs
The Node Descriptor Sub-TLV type code points and lengths are listed The Node Descriptor sub-TLV type code points and lengths are listed
in the following table: in the following table:
+====================+================================+==========+ +====================+================================+==========+
| Sub-TLV Code Point | Description | Length | | Sub-TLV Code Point | Description | Length |
+====================+================================+==========+ +====================+================================+==========+
| 512 | Autonomous System | 4 | | 512 | Autonomous System | 4 |
+--------------------+--------------------------------+----------+ +--------------------+--------------------------------+----------+
| 513 | BGP-LS Identifier (deprecated) | 4 | | 513 | BGP-LS Identifier (deprecated) | 4 |
+--------------------+--------------------------------+----------+ +--------------------+--------------------------------+----------+
| 514 | OSPF Area-ID | 4 | | 514 | OSPF Area-ID | 4 |
skipping to change at page 19, line 25 skipping to change at line 833
+--------------------+--------------------------------+----------+ +--------------------+--------------------------------+----------+
Table 3: Node Descriptor Sub-TLVs Table 3: Node Descriptor Sub-TLVs
The sub-TLV values in Node Descriptor TLVs are defined as follows: The sub-TLV values in Node Descriptor TLVs are defined as follows:
Autonomous System: Opaque value (32-bit AS Number). This is an Autonomous System: Opaque value (32-bit AS Number). This is an
optional TLV. The value SHOULD be set to the AS Number associated optional TLV. The value SHOULD be set to the AS Number associated
with the BGP process originating the link-state information. An with the BGP process originating the link-state information. An
implementation MAY provide a configuration option on the BGP-LS implementation MAY provide a configuration option on the BGP-LS
Producer to use a different value; e.g., to avoid collisions when Producer to use a different value, e.g., to avoid collisions when
using private AS numbers. using private AS Numbers.
BGP-LS Identifier: Opaque value (32-bit ID). This is an optional BGP-LS Identifier: Opaque value (32-bit ID). This is an optional
TLV which has been deprecated by this document (refer to TLV that has been deprecated by this document (refer to Appendix A
Appendix A for more details). It MAY be advertised for for more details). It MAY be advertised for compatibility with
compatibility with [RFC7752] implementations. See the final [RFC7752] implementations. See the final paragraph of this
paragraph of this section for further considerations and section for further considerations and a recommended default
recommended default value. value.
OSPF Area-ID: Used to identify the 32-bit area to which the OSPF Area-ID: Used to identify the 32-bit area to which the
information advertised in the NLRI belongs. This is a mandatory information advertised in the NLRI belongs. This is a mandatory
TLV when originating information from OSPF that is derived from TLV when originating information from OSPF that is derived from
area-scope LSAs. The OSPF Area Identifier allows different NLRIs area-scope LSAs. The OSPF Area Identifier allows different NLRIs
of the same router to be differentiated on a per-area basis. It of the same router to be differentiated on a per-area basis. It
is not used for NLRIs when carrying information that is derived is not used for NLRIs when carrying information that is derived
from AS-scope LSAs as that information is not associated with a from AS-scope LSAs as that information is not associated with a
specific area. specific area.
IGP Router-ID: Opaque value. This is a mandatory TLV when IGP Router-ID: Opaque value. This is a mandatory TLV when
originating information from IS-IS, OSPF, direct or static. For originating information from IS-IS, OSPF, 'Direct', or 'Static
an IS-IS non-pseudonode, this contains a 6-octet ISO Node-ID (ISO configuration'. For an IS-IS non-pseudonode, this contains a
system-ID). For an IS-IS pseudonode corresponding to a LAN, this 6-octet ISO Node-ID (ISO System-ID). For an IS-IS pseudonode
contains the 6-octet ISO Node-ID of the Designated Intermediate corresponding to a LAN, this contains the 6-octet ISO Node-ID of
System (DIS) followed by a 1-octet, nonzero PSN identifier (7 the Designated Intermediate System (DIS) followed by a 1-octet,
octets in total). For an OSPFv2 or OSPFv3 non-pseudonode, this nonzero PSN identifier (7 octets in total). For an OSPFv2 or
contains the 4-octet Router-ID. For an OSPFv2 pseudonode OSPFv3 non-pseudonode, this contains the 4-octet Router-ID. For
representing a LAN, this contains the 4-octet Router-ID of the an OSPFv2 pseudonode representing a LAN, this contains the 4-octet
Designated Router (DR) followed by the 4-octet IPv4 address of the Router-ID of the Designated Router (DR) followed by the 4-octet
DR's interface to the LAN (8 octets in total). Similarly, for an IPv4 address of the DR's interface to the LAN (8 octets in total).
OSPFv3 pseudonode, this contains the 4-octet Router-ID of the DR Similarly, for an OSPFv3 pseudonode, this contains the 4-octet
followed by the 4-octet interface identifier of the DR's interface Router-ID of the DR followed by the 4-octet interface identifier
to the LAN (8 octets in total). The TLV size in combination with of the DR's interface to the LAN (8 octets in total). The TLV
the protocol identifier enables the decoder to determine the type size in combination with the protocol identifier enables the
of the node. For Direct or Static configuration, the value SHOULD decoder to determine the type of the node. For 'Direct' or
be taken from an IPv4 or IPv6 address (e.g. loopback interface) 'Static configuration', the value SHOULD be taken from an IPv4 or
configured on the node. When the node is running an IGP protocol, IPv6 address (e.g., loopback interface) configured on the node.
an implementation MAY choose to use the IGP Router-ID for direct When the node is running an IGP protocol, an implementation MAY
or static. choose to use the IGP Router-ID for 'Direct' or 'Static
configuration'.
There MUST be at most one instance of each sub-TLV type present in At most, there MUST be one instance of each sub-TLV type present in
any Node Descriptor. The sub-TLVs within a Node Descriptor MUST be any Node Descriptor. The sub-TLVs within a Node Descriptor MUST be
arranged in ascending order by sub-TLV type. This needs to be done arranged in ascending order by sub-TLV type. This needs to be done
to compare NLRIs, even when an implementation encounters an unknown to compare NLRIs, even when an implementation encounters an unknown
sub-TLV. Using stable sorting, an implementation can do a binary sub-TLV. Using stable sorting, an implementation can do a binary
comparison of NLRIs and hence allow incremental deployment of new key comparison of NLRIs and hence allow incremental deployment of new key
sub-TLVs. sub-TLVs.
The BGP-LS Identifier was introduced by [RFC7752] and its use is The BGP-LS Identifier was introduced by [RFC7752], and its use is
being deprecated by this document. Implementations SHOULD support being deprecated by this document. Implementations SHOULD support
the advertisement of this sub-TLV for backward compatibility in the advertisement of this sub-TLV for backward compatibility in
deployments where there are BGP-LS Producer implementations that deployments where there are BGP-LS Producer implementations that
conform to [RFC7752] to ensure consistency of NLRI encoding for link- conform to [RFC7752] to ensure consistency of NLRI encoding for link-
state objects. The default value of 0 is RECOMMENDED to be used when state objects. The default value of 0 is RECOMMENDED to be used when
a BGP-LS Producer includes this sub-TLV when originating information a BGP-LS Producer includes this sub-TLV when originating information
into BGP-LS. Implementations SHOULD provide an option to configure into BGP-LS. Implementations SHOULD provide an option to configure
this value for backward compatibility reasons. As a reminder, the this value for backward compatibility reasons. As a reminder, the
use of the BGP-LS Instance-ID that is carried in the Identifier field use of the BGP-LS Instance-ID that is carried in the Identifier field
is the way of segregation of link-state objects of different IGP is the way of segregation of link-state objects of different IGP
skipping to change at page 21, line 18 skipping to change at line 919
is similar to the 'two-way connectivity check' that is performed by is similar to the 'two-way connectivity check' that is performed by
link-state IGPs. link-state IGPs.
An implementation MAY suppress the advertisement of a Link NLRI, An implementation MAY suppress the advertisement of a Link NLRI,
corresponding to a half-link, from a link-state IGP unless the IGP corresponding to a half-link, from a link-state IGP unless the IGP
has verified that the link is being reported in the IS-IS LSP or OSPF has verified that the link is being reported in the IS-IS LSP or OSPF
Router LSA by both the nodes connected by that link. This 'two-way Router LSA by both the nodes connected by that link. This 'two-way
connectivity check' is performed by link-state IGPs during their connectivity check' is performed by link-state IGPs during their
computation and can be leveraged before passing information for any computation and can be leveraged before passing information for any
half-link that is reported from these IGPs into BGP-LS. This ensures half-link that is reported from these IGPs into BGP-LS. This ensures
that only those Link State IGP adjacencies which are established get that only those link-state IGP adjacencies that are established get
reported via Link NLRIs. Such a 'two-way connectivity check' could reported via Link NLRIs. Such a 'two-way connectivity check' could
be also required in certain cases (e.g., with OSPF) to obtain the also be required in certain cases (e.g., with OSPF) to obtain the
proper link identifiers of the remote node. proper link identifiers of the remote node.
The format and semantics of the Value fields in most Link Descriptor The format and semantics of the Value fields in most Link Descriptor
TLVs correspond to the format and semantics of value fields in IS-IS TLVs correspond to the format and semantics of Value fields in IS-IS
Extended IS Reachability sub-TLVs, defined in [RFC5305], [RFC5307], Extended IS Reachability sub-TLVs, which are defined in [RFC5305],
and [RFC6119]. Although the encodings for Link Descriptor TLVs were [RFC5307], and [RFC6119]. Although the encodings for Link Descriptor
originally defined for IS-IS, the TLVs can carry data sourced by TLVs were originally defined for IS-IS, the TLVs can carry data
either IS-IS or OSPF. sourced by either IS-IS or OSPF.
The following TLVs are defined as Link Descriptors in the Link NLRI: The following TLVs are defined as Link Descriptors in the Link NLRI:
+================+===================+============+===============+ +================+===================+============+=============+
| TLV Code Point | Description | IS-IS TLV/ | Reference | | TLV Code Point | Description | IS-IS TLV/ | Reference |
| | | Sub-TLV | (RFC/Section) | | | | Sub-TLV | |
+================+===================+============+===============+ +================+===================+============+=============+
| 258 | Link Local/Remote | 22/4 | [RFC5307] / | | 258 | Link Local/Remote | 22/4 | [RFC5307], |
| | Identifiers | | 1.1 | | | Identifiers | | Section 1.1 |
+----------------+-------------------+------------+---------------+ +----------------+-------------------+------------+-------------+
| 259 | IPv4 interface | 22/6 | [RFC5305] / | | 259 | IPv4 interface | 22/6 | [RFC5305], |
| | address | | 3.2 | | | address | | Section 3.2 |
+----------------+-------------------+------------+---------------+ +----------------+-------------------+------------+-------------+
| 260 | IPv4 neighbor | 22/8 | [RFC5305] / | | 260 | IPv4 neighbor | 22/8 | [RFC5305], |
| | address | | 3.3 | | | address | | Section 3.3 |
+----------------+-------------------+------------+---------------+ +----------------+-------------------+------------+-------------+
| 261 | IPv6 interface | 22/12 | [RFC6119] / | | 261 | IPv6 interface | 22/12 | [RFC6119], |
| | address | | 4.2 | | | address | | Section 4.2 |
+----------------+-------------------+------------+---------------+ +----------------+-------------------+------------+-------------+
| 262 | IPv6 neighbor | 22/13 | [RFC6119] / | | 262 | IPv6 neighbor | 22/13 | [RFC6119], |
| | address | | 4.3 | | | address | | Section 4.3 |
+----------------+-------------------+------------+---------------+ +----------------+-------------------+------------+-------------+
| 263 | Multi-Topology | --- | Section | | 263 | Multi-Topology | --- | Section |
| | Identifier | | 5.2.2.1 | | | Identifier | | 5.2.2.1 |
+----------------+-------------------+------------+---------------+ +----------------+-------------------+------------+-------------+
Table 4: Link Descriptor TLVs Table 4: Link Descriptor TLVs
The information about a link present in the LSA/LSP originated by the The information about a link present in the LSA/LSP originated by the
local node of the link determines the set of TLVs in the Link local node of the link determines the set of TLVs in the Link
Descriptor of the link. Descriptor of the link.
If interface and neighbor addresses, either IPv4 or IPv6, are If interface and neighbor addresses, either IPv4 or IPv6, are
present, then the interface/neighbor address TLVs MUST be present, then the interface/neighbor address TLVs MUST be
included, and the Link Local/Remote Identifiers TLV MUST NOT be included, and the Link Local/Remote Identifiers TLV MUST NOT be
included in the Link Descriptor. The Link Local/Remote included in the Link Descriptor. The Link Local/Remote
Identifiers TLV MAY be included in the link attribute when Identifiers TLV MAY be included in the link attribute when
available. IPv4/IPv6 link-local addresses MUST NOT be carried in available. IPv4/IPv6 link-local addresses MUST NOT be carried in
the IPv4/IPv6 interface/neighbor address TLVs (259/260/261/262) as the IPv4/IPv6 interface/neighbor address TLVs (259/260/261/262) as
descriptors of a link as they are not considered unique. descriptors of a link since they are not considered unique.
If interface and neighbor addresses are not present and the link If interface and neighbor addresses are not present and the link
local/remote identifiers are present, then the Link Local/Remote local/remote identifiers are present, then the Link Local/Remote
Identifiers TLV MUST be included in the Link Descriptor. The Link Identifiers TLV MUST be included in the Link Descriptor. The Link
Local/Remote Identifiers MUST be included in the Link Descriptor Local/Remote identifiers MUST be included in the Link Descriptor
also in the case of links having only IPv6 link-local addressing and in the case of links having only IPv6 link-local addressing on
on them. them.
The Multi-Topology Identifier TLV MUST be included as a Link The Multi-Topology Identifier TLV MUST be included as a Link
Descriptor if the underlying IGP link object is associated with a Descriptor if the underlying IGP link object is associated with a
non-default topology. non-default topology.
The TLVs/sub-TLVs corresponding to the interface addresses and/or the The TLVs/sub-TLVs corresponding to the interface addresses and/or the
local/remote identifiers may not always be signaled in the IGPs local/remote identifiers may not always be signaled in the IGPs
unless their advertisement is enabled specifically. In such cases, unless their advertisement is enabled specifically. In such cases,
it is valid to advertise a BGP-LS Link NLRI without any of these it is valid to advertise a BGP-LS Link NLRI without any of these
identifiers. identifiers.
5.2.2.1. Multi-Topology ID 5.2.2.1. Multi-Topology Identifier
The Multi-Topology ID (MT-ID) TLV carries one or more IS-IS or OSPF The Multi-Topology Identifier (MT-ID) TLV carries one or more IS-IS
Multi-Topology IDs for a link, node, or prefix. or OSPF Multi-Topology Identifiers for a link, node, or prefix.
The semantics of the IS-IS MT-ID are defined in sections 7.1 and 7.2 The semantics of the IS-IS MT-ID are defined in Sections 7.1 and 7.2
of [RFC5120]. The semantics of the OSPF MT-ID are defined in section of [RFC5120]. The semantics of the OSPF MT-ID are defined in
3.7 of [RFC4915]. If the value in the MT-ID TLV is derived from Section 3.7 of [RFC4915]. If the value in the MT-ID TLV is derived
OSPF, then the upper R bits of the MT-ID field MUST be set to 0 and from OSPF, then the upper R bits of the MT-ID field MUST be set to 0
only the values from 0 to 127 are valid for the MT-ID. and only the values from 0 to 127 are valid for the MT-ID.
The format of the MT-ID TLV is shown in the following figure. The format of the MT-ID TLV is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length=2*n | | Type | Length=2*n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R| Multi-Topology ID 1 | .... // |R R R R| Multi-Topology ID 1 | .... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// .... |R R R R| Multi-Topology ID n | // .... |R R R R| Multi-Topology ID n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Multi-Topology ID TLV Format Figure 12: Multi-Topology Identifier TLV Format
where Type is 263, Length is 2*n, and n is the number of MT-IDs The Type is 263, the length is 2*n, and n is the number of MT-IDs
carried in the TLV. carried in the TLV.
The MT-ID TLV MAY be included as a Link Descriptor, a Prefix The MT-ID TLV MAY be included as a Link Descriptor, as a Prefix
Descriptor, or in the BGP-LS Attribute of a Node NLRI. When included Descriptor, or in the BGP-LS Attribute of a Node NLRI. When included
as a Link or Prefix Descriptor, only a single MT-ID TLV containing as a Link or Prefix Descriptor, only a single MT-ID TLV containing
the MT-ID of the topology where the link or the prefix is reachable the MT-ID of the topology where the link or the prefix is reachable
is allowed. In case one wants to advertise multiple topologies for a is allowed. In case one wants to advertise multiple topologies for a
given Link Descriptor or Prefix Descriptor, multiple NLRIs MUST be given Link or Prefix Descriptor, multiple NLRIs MUST be generated
generated where each NLRI contains a single unique MT-ID. When used where each NLRI contains a single unique MT-ID. When used as a Link
as a Link or Prefix Descriptor for IS-IS, the Bits R are reserved and or Prefix Descriptor for IS-IS, the Bits R are reserved and MUST be
MUST be set to 0 (as per section 7.2 of [RFC5120]) when originated set to 0 (as per Section 7.2 of [RFC5120]) when originated and
and ignored on receipt. ignored on receipt.
In the BGP-LS Attribute of a Node NLRI, one MT-ID TLV containing the In the BGP-LS Attribute of a Node NLRI, one MT-ID TLV containing the
array of MT-IDs of all topologies where the node is reachable is array of MT-IDs of all topologies where the node is reachable is
allowed. When used in the Node Attribute TLV for IS-IS, the Bits R allowed. When used in the Node Attribute TLV for IS-IS, the Bits R
are set as per section 7.1 of [RFC5120]. are set as per Section 7.1 of [RFC5120].
5.2.3. Prefix Descriptors 5.2.3. Prefix Descriptors
The Prefix Descriptor field is a set of Type/Length/Value (TLV) The Prefix Descriptor field is a set of Type/Length/Value (TLV)
triplets. Prefix Descriptor TLVs uniquely identify an IPv4 or IPv6 triplets. Prefix Descriptor TLVs uniquely identify an IPv4 or IPv6
prefix originated by a node. The following TLVs are defined as prefix originated by a node. The following TLVs are defined as
Prefix Descriptors in the IPv4/IPv6 Prefix NLRI: Prefix Descriptors in the IPv4/IPv6 Prefix NLRI:
+================+=================+==========+===============+ +================+===========================+==========+===========+
| TLV Code Point | Description | Length | Reference | | TLV Code Point | Description | Length | Reference |
| | | | (RFC/Section) | +================+===========================+==========+===========+
+================+=================+==========+===============+ | 263 | Multi-Topology | variable | Section |
| 263 | Multi-Topology | variable | Section | | | Identifier | | 5.2.2.1 |
| | Identifier | | 5.2.2.1 | +----------------+---------------------------+----------+-----------+
+----------------+-----------------+----------+---------------+ | 264 | OSPF Route Type | 1 | Section |
| 264 | OSPF Route Type | 1 | Section | | | | | 5.2.3.1 |
| | | | 5.2.3.1 | +----------------+---------------------------+----------+-----------+
+----------------+-----------------+----------+---------------+ | 265 | IP Reachability | variable | Section |
| 265 | IP Reachability | variable | Section | | | Information | | 5.2.3.2 |
| | Information | | 5.2.3.2 | +----------------+---------------------------+----------+-----------+
+----------------+-----------------+----------+---------------+
Table 5: Prefix Descriptor TLVs Table 5: Prefix Descriptor TLVs
The Multi-Topology Identifier TLV MUST be included in the Prefix The Multi-Topology Identifier TLV MUST be included in the Prefix
Descriptor if the underlying IGP prefix object is associated with a Descriptor if the underlying IGP prefix object is associated with a
non-default topology. non-default topology.
5.2.3.1. OSPF Route Type 5.2.3.1. OSPF Route Type
The OSPF Route Type TLV is an optional TLV corresponding to Prefix The OSPF Route Type TLV is an optional TLV corresponding to Prefix
NLRIs originated from OSPF. It is used to identify the OSPF route NLRIs originated from OSPF. It is used to identify the OSPF route
type of the prefix. An OSPF prefix MAY be advertised in the OSPF type of the prefix. An OSPF prefix MAY be advertised in the OSPF
domain with multiple route types. The Route Type TLV allows the domain with multiple route types. The Route Type TLV allows the
discrimination of these advertisements. The OSPF Route Type TLV MUST discrimination of these advertisements. The OSPF Route Type TLV MUST
be included in the advertisement when the type is either being be included in the advertisement when the type is either being
signaled explicitly in the underlying LSA or can be determined via signaled explicitly in the underlying LSA or can be determined via
another LSA for the same prefix when it is not signaled explicitly another LSA for the same prefix when it is not signaled explicitly
(e.g., in the case of OSPFv2 Extended Prefix Opaque LSA [RFC7684]). (e.g., in the case of OSPFv2 Extended Prefix Opaque LSA [RFC7684]).
The route type advertised in the OSPFv2 Extended Prefix TLV (section The route type advertised in the OSPFv2 Extended Prefix TLV
2.1 of [RFC7684]) does not make a distinction between Type 1 and 2 (Section 2.1 of [RFC7684]) does not make a distinction between Type 1
for AS external and NSSA external routes. In this case, the route and 2 for AS external and Not-So-Stubby Area (NSSA) external routes.
type to be used in the BGP-LS advertisement can be determined by In this case, the route type to be used in the BGP-LS advertisement
checking the OSPFv2 External or NSSA External LSA for the prefix. A can be determined by checking the OSPFv2 External or NSSA External
similar check for the base OSPFv2 LSAs can be done to determine the LSA for the prefix. A similar check for the base OSPFv2 LSAs can be
route type to be used when the route type value 0 is carried in the done to determine the route type to be used when the route type value
OSPFv2 Extended Prefix TLV. 0 is carried in the OSPFv2 Extended Prefix TLV.
The format of the OSPF Route Type TLV is shown in the following The format of the OSPF Route Type TLV is shown in the following
figure. figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Type | | Route Type |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 13: OSPF Route Type TLV Format Figure 13: OSPF Route Type TLV Format
where the Type and Length fields of the TLV are defined in Table 5. The Type and Length fields of the TLV are defined in Table 5. The
The OSPF Route Type field follows the route types defined in the OSPF Route Type field follows the route types defined in the OSPF protocol
protocol and can be one of the following: and can be one of the following:
* Intra-Area (0x1) * Intra-Area (0x1)
* Inter-Area (0x2) * Inter-Area (0x2)
* External 1 (0x3) * External 1 (0x3)
* External 2 (0x4) * External 2 (0x4)
* NSSA 1 (0x5) * NSSA 1 (0x5)
* NSSA 2 (0x6) * NSSA 2 (0x6)
5.2.3.2. IP Reachability Information 5.2.3.2. IP Reachability Information
The IP Reachability Information TLV is a mandatory TLV for IPv4 & The IP Reachability Information TLV is a mandatory TLV for IPv4 &
IPv6 Prefix NLRI types. The TLV contains one IP address prefix (IPv4 IPv6 Prefix NLRI types. The TLV contains one IP address prefix (IPv4
or IPv6) originally advertised in the IGP topology. A router SHOULD or IPv6) originally advertised in the IGP topology. A router SHOULD
advertise an IP Prefix NLRI for each of its BGP next-hops. The advertise an IP Prefix NLRI for each of its BGP next hops. The
format of the IP Reachability Information TLV is shown in the format of the IP Reachability Information TLV is shown in the
following figure: following figure:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | IP Prefix (variable) // | Prefix Length | IP Prefix (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: IP Reachability Information TLV Format Figure 14: IP Reachability Information TLV Format
The Type and Length fields of the TLV are defined in Table 5. The The Type and Length fields of the TLV are defined in Table 5. The
following two fields determine the reachability information of the following two fields determine the reachability information of the
address family. The Prefix Length field contains the length of the address family. The Prefix Length field contains the length of the
prefix in bits. The IP Prefix field contains an IP address prefix, prefix in bits. The IP Prefix field contains an IP address prefix
followed by the minimum number of trailing bits needed to make the followed by the minimum number of trailing bits needed to make the
end of the field fall on an octet boundary. Any trailing bits MUST end of the field fall on an octet boundary. Any trailing bits MUST
be set to 0. Thus, the IP Prefix field contains the most significant be set to 0. Thus, the IP Prefix field contains the most significant
octets of the prefix, i.e., 1 octet for prefix length 1 up to 8, 2 octets of the prefix, i.e., 1 octet for prefix length 1 up to 8, 2
octets for prefix length 9 to 16, 3 octets for prefix length 17 up to octets for prefix length 9 up to 16, 3 octets for prefix length 17 up
24, 4 octets for prefix length 25 up to 32, etc. to 24, 4 octets for prefix length 25 up to 32, etc.
5.3. The BGP-LS Attribute 5.3. The BGP-LS Attribute
The BGP-LS Attribute (assigned value 29 by IANA) is an optional, non- The BGP-LS Attribute (assigned value 29 by IANA) is an optional, non-
transitive BGP attribute that is used to carry link, node, and prefix transitive BGP Attribute that is used to carry link, node, and prefix
parameters and attributes. It is defined as a set of Type/Length/ parameters and attributes. It is defined as a set of Type/Length/
Value (TLV) triplets, described in the following section. This Value (TLV) triplets, as described in the following section. This
attribute SHOULD only be included with Link-State NLRIs. The use of attribute SHOULD only be included with Link-State NLRIs. The use of
this attribute for other address families is outside the scope of this attribute for other address families is outside the scope of
this document. this document.
The Node Attribute TLVs, Link Attribute TLVs, and Prefix Attribute The Node Attribute TLVs, Link Attribute TLVs, and Prefix Attribute
TLVs are sets of TLVs that may be encoded in the BGP-LS Attribute TLVs are sets of TLVs that may be encoded in the BGP-LS Attribute
associated with a Node NLRI, Link NLRI, and Prefix NLRI respectively. associated with a Node NLRI, Link NLRI, and Prefix NLRI respectively.
The size of the BGP-LS Attribute may potentially grow large depending The size of the BGP-LS Attribute may potentially grow large,
on the amount of link-state information associated with a single depending on the amount of link-state information associated with a
Link-State NLRI. The BGP specification [RFC4271] mandates a maximum single Link-State NLRI. The BGP specification [RFC4271] mandates a
BGP message size of 4096 octets. It is RECOMMENDED that an maximum BGP message size of 4096 octets. It is RECOMMENDED that an
implementation supports [RFC8654] to accommodate a larger size of implementation supports [RFC8654] to accommodate a larger size of
information within the BGP-LS Attribute. BGP-LS Producers MUST information within the BGP-LS Attribute. BGP-LS Producers MUST
ensure that the TLVs included in the BGP-LS Attribute does not result ensure that the TLVs included in the BGP-LS Attribute does not result
in a BGP UPDATE message for a single Link-State NLRI that crosses the in a BGP UPDATE message for a single Link-State NLRI that crosses the
maximum limit for a BGP message. maximum limit for a BGP message.
An implementation MAY adopt mechanisms to avoid this problem that may An implementation MAY adopt mechanisms to avoid this problem that may
be based the BGP-LS Consumer applications' requirement; these be based on the BGP-LS Consumer applications' requirement; these
mechanisms are beyond the scope of this specification. However, if mechanisms are beyond the scope of this specification. However, if
an implementation chooses to mitigate the problem by excluding some an implementation chooses to mitigate the problem by excluding some
TLVs from the BGP-LS Attribute, this exclusion SHOULD be done TLVs from the BGP-LS Attribute, this exclusion SHOULD be done
consistently by all BGP-LS Producers within a given BGP-LS domain. consistently by all BGP-LS Producers within a given BGP-LS domain.
In the event of inconsistent exclusion of TLVs from the BGP-LS In the event of inconsistent exclusion of TLVs from the BGP-LS
Attribute, the result would be a differing set of attributes of the Attribute, the result would be a differing set of attributes of the
link-state object being propagated to BGP-LS Consumers based on the link-state object being propagated to BGP-LS Consumers based on the
BGP decision process at BGP-LS Propagators. BGP Decision Process at BGP-LS Propagators.
When a BGP-LS Propagator finds that it is exceeding the maximum BGP When a BGP-LS Propagator finds that it is exceeding the maximum BGP
message size due to the addition or update of some other BGP message size due to the addition or update of some other BGP
Attribute (e.g. AS_PATH), it MUST consider the BGP-LS Attribute to Attribute (e.g., AS_PATH), it MUST consider the BGP-LS Attribute to
be malformed, apply the "Attribute Discard" error-handling approach be malformed, apply the 'Attribute Discard' error-handling approach
[RFC7606], and handle the propagation as described in Section 8.2.2. [RFC7606], and handle the propagation as described in Section 8.2.2.
When a BGP-LS Propagator needs to perform "Attribute Discard" for When a BGP-LS Propagator needs to perform 'Attribute Discard' for
reducing the BGP UPDATE message size as specified in section 4 of reducing the BGP UPDATE message size as specified in Section 4 of
[RFC8654], it MUST first discard the BGP-LS Attribute to enable the [RFC8654], it MUST first discard the BGP-LS Attribute to enable the
detection and diagnosis of this error condition as discussed in detection and diagnosis of this error condition as discussed in
Section 8.2.2. This brings the deployment consideration that the Section 8.2.2. This brings the deployment consideration that the
consistent propagation of BGP-LS information with a BGP UPDATE consistent propagation of BGP-LS information with a BGP UPDATE
message size larger than 4096 octets can only happen along a set of message size larger than 4096 octets can only happen along a set of
BGP Speakers that all support [RFC8654]. BGP Speakers that all support the contents of [RFC8654].
5.3.1. Node Attribute TLVs 5.3.1. Node Attribute TLVs
The following Node Attribute TLVs are defined for the BGP-LS The following Node Attribute TLVs are defined for the BGP-LS
Attribute associated with a Node NLRI: Attribute associated with a Node NLRI:
+================+================+==========+===============+ +================+================+==========+=============+
| TLV Code Point | Description | Length | Reference | | TLV Code Point | Description | Length | Reference |
| | | | (RFC/Section) | +================+================+==========+=============+
+================+================+==========+===============+ | 263 | Multi-Topology | variable | Section |
| 263 | Multi-Topology | variable | Section | | | Identifier | | 5.2.2.1 |
| | Identifier | | 5.2.2.1 | +----------------+----------------+----------+-------------+
+----------------+----------------+----------+---------------+ | 1024 | Node Flag Bits | 1 | Section |
| 1024 | Node Flag Bits | 1 | Section | | | | | 5.3.1.1 |
| | | | 5.3.1.1 | +----------------+----------------+----------+-------------+
+----------------+----------------+----------+---------------+ | 1025 | Opaque Node | variable | Section |
| 1025 | Opaque Node | variable | Section | | | Attribute | | 5.3.1.5 |
| | Attribute | | 5.3.1.5 | +----------------+----------------+----------+-------------+
+----------------+----------------+----------+---------------+ | 1026 | Node Name | variable | Section |
| 1026 | Node Name | variable | Section | | | | | 5.3.1.3 |
| | | | 5.3.1.3 | +----------------+----------------+----------+-------------+
+----------------+----------------+----------+---------------+ | 1027 | IS-IS Area | variable | Section |
| 1027 | IS-IS Area | variable | Section | | | Identifier | | 5.3.1.2 |
| | Identifier | | 5.3.1.2 | +----------------+----------------+----------+-------------+
+----------------+----------------+----------+---------------+ | 1028 | IPv4 Router-ID | 4 | [RFC5305], |
| 1028 | IPv4 Router-ID | 4 | [RFC5305] / | | | of Local Node | | Section 4.3 |
| | of Local Node | | 4.3 | +----------------+----------------+----------+-------------+
+----------------+----------------+----------+---------------+ | 1029 | IPv6 Router-ID | 16 | [RFC6119], |
| 1029 | IPv6 Router-ID | 16 | [RFC6119] / | | | of Local Node | | Section 4.1 |
| | of Local Node | | 4.1 | +----------------+----------------+----------+-------------+
+----------------+----------------+----------+---------------+
Table 6: Node Attribute TLVs Table 6: Node Attribute TLVs
5.3.1.1. Node Flag Bits TLV 5.3.1.1. Node Flag Bits TLV
The Node Flag Bits TLV carries a bitmask describing node attributes. The Node Flag Bits TLV carries a bitmask describing node attributes.
The value is a 1 octet length bit array of flags, where each bit The value is a 1-octet-length bit array of flags, where each bit
represents a node operational state or attribute. represents a node-operational state or attribute.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|O|T|E|B|R|V| | |O|T|E|B|R|V| |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 15: Node Flag Bits TLV Format Figure 15: Node Flag Bits TLV Format
The bits are defined as follows: The bits are defined as follows:
+=====+==============+============+ +=====+==============+============+
| Bit | Description | Reference | | Bit | Description | Reference |
+=====+==============+============+ +=====+==============+============+
| 'O' | Overload Bit | [ISO10589] | | 'O' | Overload Bit | [ISO10589] |
+-----+--------------+------------+ +-----+--------------+------------+
| 'T' | Attached Bit | [ISO10589] | | 'A' | Attached Bit | [ISO10589] |
+-----+--------------+------------+ +-----+--------------+------------+
| 'E' | External Bit | [RFC2328] | | 'E' | External Bit | [RFC2328] |
+-----+--------------+------------+ +-----+--------------+------------+
| 'B' | ABR Bit | [RFC2328] | | 'B' | ABR Bit | [RFC2328] |
+-----+--------------+------------+ +-----+--------------+------------+
| 'R' | Router Bit | [RFC5340] | | 'R' | Router Bit | [RFC5340] |
+-----+--------------+------------+ +-----+--------------+------------+
| 'V' | V6 Bit | [RFC5340] | | 'V' | V6 Bit | [RFC5340] |
+-----+--------------+------------+ +-----+--------------+------------+
skipping to change at page 29, line 49 skipping to change at line 1280
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// IS-IS Area Identifier (variable) // // IS-IS Area Identifier (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: IS-IS Area Identifier TLV Format Figure 16: IS-IS Area Identifier TLV Format
5.3.1.3. Node Name TLV 5.3.1.3. Node Name TLV
The Node Name TLV is optional. The encoding semantics for the node The Node Name TLV is optional. The encoding semantics for the node
name has been borrowed from [RFC5301]. The Value field identifies name has been borrowed from [RFC5301]. The Value field identifies
the symbolic name of the router node. This symbolic name can either the symbolic name of the router node. This symbolic name can be the
be the Fully Qualified Domain Name (FQDN) for the router, or it can Fully Qualified Domain Name (FQDN) for the router, a substring of the
be a substring of the FQDN (e.g., a hostname), or it can be any FQDN (e.g., a hostname), or any string that an operator wants to use
string that an operator wants to use for the router. The use of FQDN for the router. The use of the FQDN or a substring of it is strongly
or a substring of it is strongly RECOMMENDED. The maximum length of RECOMMENDED. The maximum length of the Node Name TLV is 255 octets.
the Node Name TLV is 255 octets.
The Value field is encoded in 7-bit ASCII. If a user interface for The Value field is encoded in 7-bit ASCII. If a user interface for
configuring or displaying this field permits Unicode characters, that configuring or displaying this field permits Unicode characters, then
the user interface is responsible for applying the ToASCII and/or the user interface is responsible for applying the ToASCII and/or
ToUnicode algorithm as described in [RFC5890] to achieve the correct ToUnicode algorithm as described in [RFC5890] to achieve the correct
format for transmission or display. format for transmission or display.
[RFC5301] describes an IS-IS-specific extension and [RFC5642] [RFC5301] describes an IS-IS-specific extension, and [RFC5642]
describes an OSPF extension for the advertisement of Node Name which describes an OSPF extension for the advertisement of the node name,
may be encoded in the Node Name TLV. which may be encoded in the Node Name TLV.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Node Name (variable) // // Node Name (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: Node Name Format Figure 17: Node Name Format
skipping to change at page 31, line 13 skipping to change at line 1338
definition for incremental deployment and transition. definition for incremental deployment and transition.
In the case of OSPF, this TLV MUST NOT be used to advertise TLVs In the case of OSPF, this TLV MUST NOT be used to advertise TLVs
other than those in the OSPF Router Information (RI) LSA [RFC7770]. other than those in the OSPF Router Information (RI) LSA [RFC7770].
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Opaque node attributes (variable) // // Opaque Node Attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 18: Opaque Node Attribute Format Figure 18: Opaque Node Attribute Format
The type is as specified in Table 6. Length is variable. The Type is as specified in Table 6. The length is variable.
5.3.2. Link Attribute TLVs 5.3.2. Link Attribute TLVs
Link Attribute TLVs are TLVs that may be encoded in the BGP-LS Link Attribute TLVs are TLVs that may be encoded in the BGP-LS
Attribute with a Link NLRI. Each 'Link Attribute' is a Type/Length/ Attribute with a Link NLRI. Each 'Link Attribute' is a Type/Length/
Value (TLV) triplet formatted as defined in Section 5.1. The format Value (TLV) triplet formatted as defined in Section 5.1. The format
and semantics of the Value fields in some Link Attribute TLVs and semantics of the Value fields in some Link Attribute TLVs
correspond to the format and semantics of the Value fields in IS-IS correspond to the format and semantics of the Value fields in IS-IS
Extended IS Reachability sub-TLVs, defined in [RFC5305] and Extended IS Reachability sub-TLVs, which are defined in [RFC5305] and
[RFC5307]. Other Link Attribute TLVs are defined in this document. [RFC5307]. Other Link Attribute TLVs are defined in this document.
Although the encodings for Link Attribute TLVs were originally Although the encodings for Link Attribute TLVs were originally
defined for IS-IS, the TLVs can carry data sourced by either IS-IS or defined for IS-IS, the TLVs can carry data sourced by either IS-IS or
OSPF. OSPF.
The following Link Attribute TLVs are defined for the BGP-LS The following Link Attribute TLVs are defined for the BGP-LS
Attribute associated with a Link NLRI: Attribute associated with a Link NLRI:
+================+=================+============+===============+ +================+=================+============+=============+
| TLV Code Point | Description | IS-IS TLV/ | Reference | | TLV Code Point | Description | IS-IS TLV/ | Reference |
| | | Sub-TLV | (RFC/Section) | | | | Sub-TLV | |
+================+=================+============+===============+ +================+=================+============+=============+
| 1028 | IPv4 Router-ID | 134/--- | [RFC5305] / | | 1028 | IPv4 Router-ID | 134/--- | [RFC5305], |
| | of Local Node | | 4.3 | | | of Local Node | | Section 4.3 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1029 | IPv6 Router-ID | 140/--- | [RFC6119] / | | 1029 | IPv6 Router-ID | 140/--- | [RFC6119], |
| | of Local Node | | 4.1 | | | of Local Node | | Section 4.1 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1030 | IPv4 Router-ID | 134/--- | [RFC5305] / | | 1030 | IPv4 Router-ID | 134/--- | [RFC5305], |
| | of Remote Node | | 4.3 | | | of Remote Node | | Section 4.3 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1031 | IPv6 Router-ID | 140/--- | [RFC6119] / | | 1031 | IPv6 Router-ID | 140/--- | [RFC6119], |
| | of Remote Node | | 4.1 | | | of Remote Node | | Section 4.1 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1088 | Administrative | 22/3 | [RFC5305] / | | 1088 | Administrative | 22/3 | [RFC5305], |
| | group (color) | | 3.1 | | | group (color) | | Section 3.1 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1089 | Maximum link | 22/9 | [RFC5305] / | | 1089 | Maximum link | 22/9 | [RFC5305], |
| | bandwidth | | 3.4 | | | bandwidth | | Section 3.4 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1090 | Max. reservable | 22/10 | [RFC5305] / | | 1090 | Max. reservable | 22/10 | [RFC5305], |
| | link bandwidth | | 3.5 | | | link bandwidth | | Section 3.5 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1091 | Unreserved | 22/11 | [RFC5305] / | | 1091 | Unreserved | 22/11 | [RFC5305], |
| | bandwidth | | 3.6 | | | bandwidth | | Section 3.6 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1092 | TE Default | 22/18 | Section | | 1092 | TE Default | 22/18 | Section |
| | Metric | | 5.3.2.3 | | | Metric | | 5.3.2.3 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1093 | Link Protection | 22/20 | [RFC5307] / | | 1093 | Link Protection | 22/20 | [RFC5307], |
| | Type | | 1.2 | | | Type | | Section 1.2 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1094 | MPLS Protocol | --- | Section | | 1094 | MPLS Protocol | --- | Section |
| | Mask | | 5.3.2.2 | | | Mask | | 5.3.2.2 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1095 | IGP Metric | --- | Section | | 1095 | IGP Metric | --- | Section |
| | | | 5.3.2.4 | | | | | 5.3.2.4 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1096 | Shared Risk | --- | Section | | 1096 | Shared Risk | --- | Section |
| | Link Group | | 5.3.2.5 | | | Link Group | | 5.3.2.5 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1097 | Opaque Link | --- | Section | | 1097 | Opaque Link | --- | Section |
| | Attribute | | 5.3.2.6 | | | Attribute | | 5.3.2.6 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
| 1098 | Link Name | --- | Section | | 1098 | Link Name | --- | Section |
| | | | 5.3.2.7 | | | | | 5.3.2.7 |
+----------------+-----------------+------------+---------------+ +----------------+-----------------+------------+-------------+
Table 8: Link Attribute TLVs Table 8: Link Attribute TLVs
5.3.2.1. IPv4/IPv6 Router-ID TLVs 5.3.2.1. IPv4/IPv6 Router-ID TLVs
The local/remote IPv4/IPv6 Router-ID TLVs are used to describe The local/remote IPv4/IPv6 Router-ID TLVs are used to describe
auxiliary Router-IDs that the IGP might be using, e.g., for TE auxiliary Router-IDs that the IGP might be using, e.g., for TE
purposes. All auxiliary Router-IDs of both the local and the remote purposes. All auxiliary Router-IDs of both the local and the remote
node MUST be included in the link attribute of each Link NLRI. If node MUST be included in the link attribute of each Link NLRI. If
there is more than one auxiliary Router-ID of a given type, then there is more than one auxiliary Router-ID of a given type, then
skipping to change at page 34, line 19 skipping to change at line 1482
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Default Link Metric | | TE Default Link Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 20: TE Default Metric TLV Format Figure 20: TE Default Metric TLV Format
5.3.2.4. IGP Metric TLV 5.3.2.4. IGP Metric TLV
The IGP Metric TLV carries the metric for this link. The length of The IGP Metric TLV carries the metric for this link. The length of
this TLV is variable, depending on the metric width of the underlying this TLV is variable, depending on the metric width of the underlying
protocol. IS-IS small metrics are of 6-bit size, but are encoded in protocol. IS-IS small metrics are 6 bits in size but are encoded in
a 1 octet field; therefore the two most significant bits of the field a 1-octet field; therefore, the two most significant bits of the
MUST be set to 0 by the originator and MUST be ignored by the field MUST be set to 0 by the originator and MUST be ignored by the
receiver. OSPF link metrics have a length of 2 octets. IS-IS wide receiver. OSPF link metrics have a length of 2 octets. IS-IS wide
metrics have a length of 3 octets. metrics have a length of 3 octets.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// IGP Link Metric (variable length) // // IGP Link Metric (variable length) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 35, line 20 skipping to change at line 1522
| Shared Risk Link Group Value | | Shared Risk Link Group Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// ............ // // ............ //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shared Risk Link Group Value | | Shared Risk Link Group Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 22: Shared Risk Link Group TLV Format Figure 22: Shared Risk Link Group TLV Format
The SRLG TLV for OSPF-TE is defined in [RFC4203]. In IS-IS, the SRLG The SRLG TLV for OSPF-TE is defined in [RFC4203]. In IS-IS, the SRLG
information is carried in two different TLVs: the IPv4 (SRLG) TLV information is carried in two different TLVs: the GMPLS-SRLG TLV (for
(Type 138) defined in [RFC5307] and the IPv6 SRLG TLV (Type 139) IPv4) (Type 138) defined in [RFC5307] and the IPv6 SRLG TLV (Type
defined in [RFC6119]. Both IPv4 and IPv6 SRLG information is carried 139) defined in [RFC6119]. Both IPv4 and IPv6 SRLG information is
in a single TLV. carried in a single TLV.
5.3.2.6. Opaque Link Attribute TLV 5.3.2.6. Opaque Link Attribute TLV
The Opaque Link Attribute TLV is an envelope that transparently The Opaque Link Attribute TLV is an envelope that transparently
carries optional Link Attribute TLVs advertised by a router. An carries optional Link Attribute TLVs advertised by a router. An
originating router shall use this TLV for encoding information originating router shall use this TLV for encoding information
specific to the protocol advertised in the NLRI header Protocol-ID specific to the protocol advertised in the NLRI header Protocol-ID
field or new protocol extensions to the protocol as advertised in the field or new protocol extensions to the protocol as advertised in the
NLRI header Protocol-ID field for which there is no protocol-neutral NLRI header Protocol-ID field for which there is no protocol-neutral
representation in the BGP Link-State NLRI. The primary use of the representation in the BGP Link-State NLRI. The primary use of the
skipping to change at page 36, line 10 skipping to change at line 1554
information carried using TLVs other than those in the OSPFv2 information carried using TLVs other than those in the OSPFv2
Extended Link Opaque LSA [RFC7684]. In the case of OSPFv3, this TLV Extended Link Opaque LSA [RFC7684]. In the case of OSPFv3, this TLV
MUST NOT be used to advertise TLVs other than those in the OSPFv3 E- MUST NOT be used to advertise TLVs other than those in the OSPFv3 E-
Router-LSA or E-Link-LSA [RFC8362]. Router-LSA or E-Link-LSA [RFC8362].
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Opaque link attributes (variable) // // Opaque Link Attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 23: Opaque Link Attribute TLV Format Figure 23: Opaque Link Attribute TLV Format
5.3.2.7. Link Name TLV 5.3.2.7. Link Name TLV
The Link Name TLV is optional. The Value field identifies the The Link Name TLV is optional. The Value field identifies the
symbolic name of the router link. This symbolic name can either be symbolic name of the router link. This symbolic name can be the FQDN
the FQDN for the link, or it can be a substring of the FQDN, or it for the link, a substring of the FQDN, or any string that an operator
can be any string that an operator wants to use for the link. The wants to use for the link. The use of the FQDN or a substring of it
use of FQDN or a substring of it is strongly RECOMMENDED. The is strongly RECOMMENDED. The maximum length of the Link Name TLV is
maximum length of the Link Name TLV is 255 octets. 255 octets.
The Value field is encoded in 7-bit ASCII. If a user interface for The Value field is encoded in 7-bit ASCII. If a user interface for
configuring or displaying this field permits Unicode characters, that configuring or displaying this field permits Unicode characters, then
the user interface is responsible for applying the ToASCII and/or the user interface is responsible for applying the ToASCII and/or
ToUnicode algorithm as described in [RFC5890] to achieve the correct ToUnicode algorithm as described in [RFC5890] to achieve the correct
format for transmission or display. format for transmission or display.
How a router derives and injects link names is outside of the scope How a router derives and injects link names is outside of the scope
of this document. of this document.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 38, line 37 skipping to change at line 1667
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Route Tags (one or more) // // Route Tags (one or more) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 26: IGP Route Tag TLV Format Figure 26: IGP Route Tag TLV Format
Length is a multiple of 4. The length is a multiple of 4.
The Value field contains one or more Route Tags as learned in the IGP The Value field contains one or more Route Tags as learned in the IGP
topology. topology.
5.3.3.3. Extended IGP Route Tag TLV 5.3.3.3. IGP Extended Route Tag TLV
The Extended IGP Route Tag TLV carries IS-IS Extended Route Tags of The IGP Extended Route Tag TLV carries IS-IS Extended Route Tags of
the prefix [RFC5130] and is encoded as follows: the prefix [RFC5130] and is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Extended Route Tag (one or more) // // Extended Route Tag (one or more) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 27: Extended IGP Route Tag TLV Format Figure 27: IGP Extended Route Tag TLV Format
Length is a multiple of 8. The length is a multiple of 8.
The Extended Route Tag field contains one or more Extended Route Tags The Extended Route Tag field contains one or more Extended Route Tags
as learned in the IGP topology. as learned in the IGP topology.
5.3.3.4. Prefix Metric TLV 5.3.3.4. Prefix Metric TLV
The Prefix Metric TLV is an optional attribute and may only appear The Prefix Metric TLV is an optional attribute and may only appear
once. If present, it carries the metric of the prefix as known in once. If present, it carries the metric of the prefix as known in
the IGP topology as described in Section 4 of [RFC5305] (and the IGP topology, as described in Section 4 of [RFC5305] (and
therefore represents the reachability cost to the prefix). If not therefore represents the reachability cost to the prefix). If not
present, it means that the prefix is advertised without any present, it means that the prefix is advertised without any
reachability. reachability.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric | | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 28: Prefix Metric TLV Format Figure 28: Prefix Metric TLV Format
Length is 4. The length is 4.
5.3.3.5. OSPF Forwarding Address TLV 5.3.3.5. OSPF Forwarding Address TLV
The OSPF Forwarding Address TLV [RFC2328] [RFC5340] carries the OSPF The OSPF Forwarding Address TLV [RFC2328] [RFC5340] carries the OSPF
forwarding address as known in the original OSPF advertisement. The forwarding address as known in the original OSPF advertisement. The
forwarding address can be either IPv4 or IPv6. forwarding address can be either IPv4 or IPv6.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Forwarding Address (variable) // // Forwarding Address (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 29: OSPF Forwarding Address TLV Format Figure 29: OSPF Forwarding Address TLV Format
Length is 4 for an IPv4 forwarding address, and 16 for an IPv6 The length is 4 for an IPv4 forwarding address and 16 for an IPv6
forwarding address. forwarding address.
5.3.3.6. Opaque Prefix Attribute TLV 5.3.3.6. Opaque Prefix Attribute TLV
The Opaque Prefix Attribute TLV is an envelope that transparently The Opaque Prefix Attribute TLV is an envelope that transparently
carries optional Prefix Attribute TLVs advertised by a router. An carries optional Prefix Attribute TLVs advertised by a router. An
originating router shall use this TLV for encoding information originating router shall use this TLV for encoding information
specific to the protocol advertised in the NLRI header Protocol-ID specific to the protocol advertised in the NLRI header Protocol-ID
field or new protocol extensions to the protocol as advertised in the field or it shall use new protocol extensions for the protocol as
NLRI header Protocol-ID field for which there is no protocol-neutral advertised in the NLRI header Protocol-ID field for which there is no
representation in the BGP Link-State NLRI. The primary use of the protocol-neutral representation in the BGP Link-State NLRI. The
Opaque Prefix Attribute TLV is to bridge the document lag between a primary use of the Opaque Prefix Attribute TLV is to bridge the
new IGP link-state attribute and its protocol-neutral BGP-LS document lag between a new IGP link-state attribute and its protocol-
extension being defined. Once the protocol-neutral BGP-LS extensions neutral BGP-LS extension being defined. Once the protocol-neutral
are defined, the BGP-LS implementations may still need to advertise BGP-LS extensions are defined, the BGP-LS implementations may still
the information both within the Opaque Attribute TLV and the new TLV need to advertise the information both within the Opaque Attribute
definition for incremental deployment and transition. TLV and the new TLV definition for incremental deployment and
transition.
In the case of OSPFv2, this TLV MUST NOT be used to advertise In the case of OSPFv2, this TLV MUST NOT be used to advertise
information carried using TLVs other than those in the OSPFv2 information carried using TLVs other than those in the OSPFv2
Extended Prefix Opaque LSA [RFC7684]. In the case of OSPFv3, this Extended Prefix Opaque LSA [RFC7684]. In the case of OSPFv3, this
TLV MUST NOT be used to advertise TLVs other than those in the OSPFv3 TLV MUST NOT be used to advertise TLVs other than those in the OSPFv3
E-Inter-Area-Prefix-LSA, E-Intra-Area-Prefix-LSA, E-AS-External- E-Inter-Area-Prefix-LSA, E-Intra-Area-Prefix-LSA, E-AS-External-LSA,
Prefix-LSA, and E-NSSA-LSA [RFC8362]. and E-NSSA-LSA [RFC8362].
The format of the TLV is as follows: The format of the TLV is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Opaque Prefix Attributes (variable) // // Opaque Prefix Attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 30: Opaque Prefix Attribute TLV Format Figure 30: Opaque Prefix Attribute TLV Format
The type is as specified in Table 10. Length is variable. The Type is as specified in Table 10. The length is variable.
5.4. Private Use 5.4. Private Use
TLVs for Vendor Private use are supported using the code point range TLVs for Vendor Private Use are supported using the code point range
reserved as indicated in Section 7. For such TLV use in the NLRI or reserved as indicated in Section 7. For such TLV use in the NLRI or
BGP-LS Attribute, the format as described in Section 5.1 is to be BGP-LS Attribute, the format described in Section 5.1 is to be used
used and a 4-octet field MUST be included as the first field in the and a 4-octet field MUST be included as the first field in the value
value to carry the Enterprise Code. For a private use NLRI Type, a 4 to carry the Enterprise Code. For a private use NLRI type, a 4-octet
octet field MUST be included as the first field in the NLRI field MUST be included as the first field in the NLRI immediately
immediately following the Total NLRI Length field of the Link-State following the Total NLRI Length field of the Link-State NLRI format
NLRI format as described in Section 5.2 to carry the Enterprise Code as described in Section 5.2 to carry the Enterprise Code [ENTNUM].
[ENTNUM]. This enables the use of vendor-specific extensions without This enables the use of vendor-specific extensions without conflicts.
conflicts.
Multiple instances of private-use TLVs MAY appear in the BGP-LS Multiple instances of private-use TLVs MAY appear in the BGP-LS
Attribute. Attribute.
5.5. BGP Next-Hop Information 5.5. BGP Next-Hop Information
BGP link-state information for both IPv4 and IPv6 networks can be BGP link-state information for both IPv4 and IPv6 networks can be
carried over either an IPv4 BGP session or an IPv6 BGP session. If carried over either an IPv4 BGP session or an IPv6 BGP session. If
an IPv4 BGP session is used, then the next-hop in the MP_REACH_NLRI an IPv4 BGP session is used, then the next hop in the MP_REACH_NLRI
SHOULD be an IPv4 address. Similarly, if an IPv6 BGP session is SHOULD be an IPv4 address. Similarly, if an IPv6 BGP session is
used, then the next-hop in the MP_REACH_NLRI SHOULD be an IPv6 used, then the next hop in the MP_REACH_NLRI SHOULD be an IPv6
address. Usually, the next-hop will be set to the local endpoint address. Usually, the next hop will be set to the local endpoint
address of the BGP session. The next-hop address MUST be encoded as address of the BGP session. The next-hop address MUST be encoded as
described in [RFC4760]. The Length field of the next-hop address described in [RFC4760]. The Length field of the next-hop address
will specify the next-hop address family. If the next-hop length is will specify the next-hop address family. If the next-hop length is
4, then the next-hop is an IPv4 address; if the next-hop length is 4, then the next hop is an IPv4 address; if the next-hop length is
16, then it is a global IPv6 address; and if the next-hop length is 16, then it is a global IPv6 address; and if the next-hop length is
32, then there is one global IPv6 address followed by a link-local 32, then there is one global IPv6 address followed by an IPv6 link-
IPv6 address. The link-local IPv6 address should be used as local address. The IPv6 link-local address should be used as
described in [RFC2545]. For VPN Subsequent Address Family Identifier described in [RFC2545]. For VPN Subsequent Address Family Identifier
(SAFI), as per custom, an 8-byte Route Distinguisher set to all zero (SAFI), as per custom, an 8-byte Route Distinguisher set to all zero
is prepended to the next-hop. is prepended to the next hop.
The BGP Next-Hop is used by each BGP-LS speaker to validate the NLRI The BGP Next-Hop is used by each BGP-LS Speaker to validate the NLRI
it receives. In case identical NLRIs are sourced by multiple BGP-LS it receives. In case identical NLRIs are sourced by multiple BGP-LS
Producers, the BGP Next-Hop is used to tiebreak as per the standard Producers, the BGP Next-Hop is used to tiebreak as per the standard
BGP path decision process. This specification doesn't mandate any BGP path decision process. This specification doesn't mandate any
rule regarding the rewrite of the BGP Next-Hop. rule regarding the rewrite of the BGP Next-Hop.
5.6. Inter-AS Links 5.6. Inter-AS Links
The main source of TE information is the IGP, which is not active on The main source of TE information is the IGP, which is not active on
inter-AS links. In some cases, the IGP may have information of inter-AS links. In some cases, the IGP may have information of
inter-AS links [RFC5392] [RFC9346]. In other cases, an inter-AS links [RFC5392] [RFC9346]. In other cases, an
implementation SHOULD provide a means to inject inter-AS links into implementation SHOULD provide a means to inject inter-AS links into
BGP-LS. The exact mechanism used to advertise the inter-AS links is BGP-LS. The exact mechanism used to advertise the inter-AS links is
outside the scope of this document. outside the scope of this document.
5.7. OSPF Virtual Links and Sham Links 5.7. OSPF Virtual Links and Sham Links
In an OSPF [RFC2328] [RFC5340] network, OSPF virtual links serve to In an OSPF [RFC2328] [RFC5340] network, OSPF virtual links serve to
connect physically separate components of the backbone to establish/ connect physically separate components of the backbone to establish/
maintain continuity of the backbone area. While OSPF virtual links maintain continuity of the backbone area. While OSPF virtual links
are modeled as point-to-point unnumbered links in the OSPF topology, are modeled as point-to-point, unnumbered links in the OSPF topology,
their characteristics and purpose are different from other types of their characteristics and purpose are different from other types of
links in the OSPF topology. They are advertised using a distinct links in the OSPF topology. They are advertised using a distinct
"virtual link" type in OSPF LSAs. The mechanism for the "virtual link" type in OSPF LSAs. The mechanism for the
advertisement of OSPF virtual links via BGP-LS is outside the scope advertisement of OSPF virtual links via BGP-LS is outside the scope
of this document. of this document.
In an OSPF network, sham links [RFC4577] [RFC6565] are used to In an OSPF network, sham links [RFC4577] [RFC6565] are used to
provide intra-area connectivity between VPN Routing and Forwarding provide intra-area connectivity between VPN Routing and Forwarding
(VRF) instances on PE routers over the VPN provider's network. These (VRF) instances on Provider Edge (PE) routers over the VPN provider's
links are advertised in OSPF as point-to-point unnumbered links and network. These links are advertised in OSPF as point-to-point,
represent connectivity over a service provider network using unnumbered links and represent connectivity over a service provider
encapsulation mechanisms like MPLS. As such, the mechanism for the network using encapsulation mechanisms like MPLS. As such, the
advertisement of OSPF sham links follows the same procedures as other mechanism for the advertisement of OSPF sham links follows the same
point-to-point unnumbered links as described previously in this procedures as other point-to-point, unnumbered links as described
document. previously in this document.
5.8. OSPFv2 Type 4 Summary LSA & OSPFv3 Inter-Area Router LSA 5.8. OSPFv2 Type 4 Summary-LSA & OSPFv3 Inter-Area-Router-LSA
OSPFv2 [RFC2328] defines the Type 4 Summary LSA and OSPFv3 [RFC5340] OSPFv2 [RFC2328] defines the type 4 summary-LSA and OSPFv3 [RFC5340]
the Inter-area-router-LSA for an Area Border Router (ABR) to defines the inter-area-router-LSA for an Area Border Router (ABR) to
advertise reachability to an AS Border Router (ASBR) that is external advertise reachability to an AS Border Router (ASBR) that is external
to the area yet internal to the AS. The nature of information to the area yet internal to the AS. The nature of information
advertised by OSPF using this type of LSA does not map to either a advertised by OSPF using this type of LSA does not map to either a
node or a link or a prefix as discussed in this document. Therefore, node, a link, or a prefix as discussed in this document. Therefore,
the mechanism for the advertisement of the information carried by the mechanism for the advertisement of the information carried by
these LSAs is outside the scope of this document. these LSAs is outside the scope of this document.
5.9. Handling of Unreachable IGP Nodes 5.9. Handling of Unreachable IGP Nodes
Consider an OSPF network as shown in Figure 31, where R2 and R3 are Consider an OSPF network as shown in Figure 31, where R2 and R3 are
the BGP-LS Producers and also the OSPF Area Border Routers (ABRs). the BGP-LS Producers and also the OSPF Area Border Routers (ABRs).
The link between R2 and R3 is in area 0 while the other links are in The link between R2 and R3 is in area 0, while the other links are in
area 1 as indicated by the a0 and a1 references respectively against area 1 as indicated by the a0 and a1 references respectively against
the links. the links.
A BGP-LS Consumer talks to a BGP route reflector RR0 which is a BGP- A BGP-LS Consumer talks to BGP route reflector RR0, which is a BGP-LS
LS Propagator that is aggregating the BGP-LS feed from the BGP-LS Propagator that is aggregating the BGP-LS feed from BGP-LS Producers
Producers R2 and R3. Here R2 and R3 provide a redundant topology R2 and R3. Here, R2 and R3 provide a redundant topology feed via
feed via BGP-LS to RR0. Normally, RR0 would receive two identical BGP-LS to RR0. Normally, RR0 would receive two identical copies of
copies of all the Link-State NLRIs from both R2 and R3 and it would all the Link-State NLRIs from both R2 and R3 and it would pick one of
pick one of them (say R2) based on the standard BGP Decision Process. them (say R2) based on the standard BGP Decision Process.
BGP-LS Consumer BGP-LS Consumer
^ ^
| |
RR0 RR0
(BGP Route Reflector) (BGP Route Reflector)
/ \ / \
/ \ / \
a1 / a0 \ a1 a1 / a0 \ a1
R1 ------ R2 -------- R3 ------ R4 R1 ------ R2 -------- R3 ------ R4
a1 | | a1 a1 | | a1
| | | |
R5 ---------------------------- R6 R5 ---------------------------- R6
a1 a1
Figure 31: Incorrect Reporting due to BGP Path Selection Figure 31: Incorrect Reporting Due to BGP Path Selection
Consider a scenario where the link between R5 and R6 is lost (thereby Consider a scenario where the link between R5 and R6 is lost (thereby
partitioning the area 1) and its impact on the OSPF LSDB at R2 and partitioning the area 1), and consider its impact on the OSPF LSDB at
R3. R2 and R3.
Now, R5 will remove the link R5-R6 from its Router LSA, and this Now, R5 will remove the link R5-R6 from its Router LSA, and this
updated LSA is available at R2. R2 also has a stale copy of R6's updated LSA is available at R2. R2 also has a stale copy of R6's
Router LSA that still has the link R6-R5 in it. Based on this view Router LSA that still has the link R6-R5 in it. Based on this view
in its LSDB, R2 will advertise only the half-link R6-R5 that it in its LSDB, R2 will advertise only the half-link R6-R5 that it
derives from R6's stale Router LSA. derives from R6's stale Router LSA.
At the same time, R6 has removed the link R6-R5 from its Router LSA, At the same time, R6 has removed the link R6-R5 from its Router LSA,
and this updated LSA is available at R3. Similarly, R3 also has a and this updated LSA is available at R3. Similarly, R3 also has a
stale copy of R5's Router LSA having the link R5-R6 in it. Based on stale copy of R5's Router LSA having the link R5-R6 in it. Based on
its LSDB, R3 will advertise only the half-link R5-R6 that it has its LSDB, R3 will advertise only the half-link R5-R6 that it derives
derived from R5's stale Router LSA. from R5's stale Router LSA.
Now, the BGP-LS Consumer receives both the Link NLRIs corresponding Now, the BGP-LS Consumer receives both the Link NLRIs corresponding
to the half-links from R2 and R3 via RR0. When viewed together, it to the half-links from R2 and R3 via RR0. When viewed together, it
would not detect or realize that area 1 is partitioned. Also, if R2 would not detect or realize that area 1 is partitioned. Also, if R2
continues to report Node and Prefix NLRIs corresponding to the stale continues to report Node and Prefix NLRIs corresponding to the stale
copy of R4 and R6's Router LSAs then RR0 could prefer them over the copy of R4's and R6's Router LSAs, then RR0 could prefer them over
valid Node and Prefix NLRIs for R4 and R6 that it is receiving from the valid Node and Prefix NLRIs for R4 and R6 that it is receiving
R3 depending on RR0's BGP decision process. This would result in the from R3 depending on RR0's BGP Decision Process. This would result
BGP-LS Consumer getting stale and inaccurate topology information. in the BGP-LS Consumer getting stale and inaccurate topology
This problem scenario is avoided if R2 were to not advertise the information. This problem scenario is avoided if R2 were to not
link-state information corresponding to R4 and R6 and if R3 were to advertise the link-state information corresponding to R4 and R6 and
not advertise similarly for R1 and R5. if R3 were to not advertise similarly for R1 and R5.
A BGP-LS Producer SHOULD withdraw all link-state objects advertised A BGP-LS Producer SHOULD withdraw all link-state objects advertised
by it in BGP when the node that originated its corresponding LSP/LSAs by it in BGP when the node that originated its corresponding LSPs/
is determined to have become unreachable in the IGP. An LSAs is determined to have become unreachable in the IGP. An
implementation MAY continue to advertise link-state objects implementation MAY continue to advertise link-state objects
corresponding to unreachable nodes in a deployment use-case where the corresponding to unreachable nodes in a deployment use case where the
BGP-LS Consumer is interested in receiving a topology feed BGP-LS Consumer is interested in receiving a topology feed
corresponding to a complete IGP LSDB view. In such deployments, it corresponding to a complete IGP LSDB view. In such deployments, it
is expected that the problem described above is mitigated by the BGP- is expected that the problem described above is mitigated by the BGP-
LS Consumer via appropriate handling of such a topology feed in LS Consumer via appropriate handling of such a topology feed in
addition to the use of either a direct BGP peering with the BGP-LS addition to the use of either a direct BGP peering with the BGP-LS
Producer nodes or mechanisms such as [RFC7911] when using RRs. Producer nodes or mechanisms such as those described in [RFC7911]
Details of these mechanisms are outside the scope of this document. when using RRs. Details of these mechanisms are outside the scope of
this document.
If the BGP-LS Producer does withdraw link-state objects associated If the BGP-LS Producer does withdraw link-state objects associated
with an IGP node based on the failure of reachability check for that with an IGP node based on the failure of reachability check for that
node, then it MUST re-advertise those link-state objects after that node, then it MUST re-advertise those link-state objects after that
node becomes reachable again in the IGP domain. node becomes reachable again in the IGP domain.
5.10. Router-ID Anchoring Example: ISO Pseudonode 5.10. Router-ID Anchoring Example: ISO Pseudonode
The encoding of a broadcast LAN in IS-IS provides a good example of The encoding of a broadcast LAN in IS-IS provides a good example of
how Router-IDs are encoded. Consider Figure 32. This represents a how Router-IDs are encoded. Consider Figure 32. This represents a
Broadcast LAN between a pair of routers. The "real" (non-pseudonode) broadcast LAN between a pair of routers. The "real" (non-pseudonode)
routers have both an IPv4 Router-ID and IS-IS Node-ID. The routers have both an IPv4 Router-ID and an IS-IS Node-ID. The
pseudonode does not have an IPv4 Router-ID. Node1 is the DIS for the pseudonode does not have an IPv4 Router-ID. Node1 is the DIS for the
LAN. Two unidirectional links (Node1, Pseudonode1) and (Pseudonode1, LAN. Two unidirectional links, (Node1, Pseudonode1) and
Node2) are being generated. (Pseudonode1, Node2), are being generated.
The Link NLRI of (Node1, Pseudonode1) is encoded as follows. The IGP The Link NLRI of (Node1, Pseudonode1) is encoded as follows. The IGP
Router-ID TLV of the local Node Descriptor is 6 octets long and Router-ID TLV of the local Node Descriptor is 6 octets long and
contains the ISO-ID of Node1, 1920.0000.2001. The IGP Router-ID TLV contains the ISO-ID of Node1, 1920.0000.2001. The IGP Router-ID TLV
of the remote Node Descriptor is 7 octets long and contains the ISO- of the remote Node Descriptor is 7 octets long and contains the ISO-
ID of Pseudonode1, 1920.0000.2001.02. The BGP-LS Attribute of this ID of Pseudonode1, 1920.0000.2001.02. The BGP-LS Attribute of this
link contains one local IPv4 Router-ID TLV (TLV type 1028) containing link contains one local IPv4 Router-ID TLV (TLV type 1028) containing
192.0.2.1, the IPv4 Router-ID of Node1. 192.0.2.1, the IPv4 Router-ID of Node1.
The Link NLRI of (Pseudonode1, Node2) is encoded as follows. The IGP The Link NLRI of (Pseudonode1, Node2) is encoded as follows. The IGP
skipping to change at page 45, line 25 skipping to change at line 1968
|1920.0000.2001.00|--->|1920.0000.2001.02|--->|1920.0000.2002.00| |1920.0000.2001.00|--->|1920.0000.2001.02|--->|1920.0000.2002.00|
| 192.0.2.1 | | | | 192.0.2.2 | | 192.0.2.1 | | | | 192.0.2.2 |
+-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 32: IS-IS Pseudonodes Figure 32: IS-IS Pseudonodes
5.11. Router-ID Anchoring Example: OSPF Pseudonode 5.11. Router-ID Anchoring Example: OSPF Pseudonode
The encoding of a broadcast LAN in OSPF provides a good example of The encoding of a broadcast LAN in OSPF provides a good example of
how Router-IDs and local Interface IPs are encoded. Consider how Router-IDs and local Interface IPs are encoded. Consider
Figure 33. This represents a Broadcast LAN between a pair of Figure 33. This represents a broadcast LAN between a pair of
routers. The "real" (non-pseudonode) routers have both an IPv4 routers. The "real" (non-pseudonode) routers have both an IPv4
Router-ID and an Area Identifier. The pseudonode does have an IPv4 Router-ID and an Area Identifier. The pseudonode does have an IPv4
Router-ID, an IPv4 Interface Address (for disambiguation), and an Router-ID, an IPv4 Interface Address (for disambiguation), and an
OSPF Area. Node1 is the DR for the LAN; hence, its local IP address OSPF Area. Node1 is the DR for the LAN; hence, its local IP address
198.51.100.1 is used as both the Router-ID and Interface IP for the 198.51.100.1 is used as both the Router-ID and Interface IP for the
pseudonode keys. Two unidirectional links, (Node1, Pseudonode1) and pseudonode keys. Two unidirectional links, (Node1, Pseudonode1) and
(Pseudonode1, Node2), are being generated. (Pseudonode1, Node2), are being generated.
The Link NLRI of (Node1, Pseudonode1) is encoded as follows: The Link NLRI of (Node1, Pseudonode1) is encoded as follows:
* Local Node Descriptor * Local Node Descriptor
TLV #515: IGP Router-ID: 192.0.2.1 TLV #515: IGP Router-ID: 192.0.2.1
TLV #514: OSPF Area-ID: ID:0.0.0.0 TLV #514: OSPF Area-ID: ID:0.0.0.0
* Remote Node Descriptor * Remote Node Descriptor
TLV #515: IGP Router-ID: 192.0.2.1:198.51.100.1 TLV #515: IGP Router-ID: 192.0.2.1:198.51.100.1
TLV #514: OSPF Area-ID: ID:0.0.0.0 TLV #514: OSPF Area-ID: ID:0.0.0.0
The Link NLRI of (Pseudonode1, Node2) is encoded as follows: The Link NLRI of (Pseudonode1, Node2) is encoded as follows:
* Local Node Descriptor * Local Node Descriptor
TLV #515: IGP Router-ID: 192.0.2.1:198.51.100.1 TLV #515: IGP Router-ID: 192.0.2.1:198.51.100.1
TLV #514: OSPF Area-ID: ID:0.0.0.0
TLV #514: OSPF Area-ID: ID:0.0.0.0
* Remote Node Descriptor * Remote Node Descriptor
TLV #515: IGP Router-ID: 192.0.2.2 TLV #515: IGP Router-ID: 192.0.2.2
TLV #514: OSPF Area-ID: ID:0.0.0.0 TLV #514: OSPF Area-ID: ID:0.0.0.0
198.51.100.1/24 198.51.100.2/24 198.51.100.1/24 198.51.100.2/24
+-------------+ +-------------+ +-------------+ +-------------+ +-------------+ +-------------+
| Node1 | | Pseudonode1 | | Node2 | | Node1 | | Pseudonode1 | | Node2 |
| 192.0.2.1 |--->| 192.0.2.1 |--->| 192.0.2.2 | | 192.0.2.1 |--->| 192.0.2.1 |--->| 192.0.2.2 |
| | |198.51.100.1 | | | | | |198.51.100.1 | | |
| Area 0 | | Area 0 | | Area 0 | | Area 0 | | Area 0 | | Area 0 |
+-------------+ +-------------+ +-------------+ +-------------+ +-------------+ +-------------+
Figure 33: OSPF Pseudonodes Figure 33: OSPF Pseudonodes
The LAN subnet 198.51.100.0/24 is not included in the Router LSA of The LAN subnet 198.51.100.0/24 is not included in the Router LSA of
Node1 or Node2. The Network LSA for this LAN advertised by the DR Node1 or Node2. The Network LSA for this LAN advertised by the DR
Node1 contains the subnet mask for the LAN along with the DR address. Node1 contains the subnet mask for the LAN along with the DR address.
A Prefix NLRI corresponding to the LAN subnet is advertised with the A Prefix NLRI corresponding to the LAN subnet is advertised with the
Pseudonode1 used as the Local node using the DR address and the Pseudonode1 used as the local node using the DR address and the
subnet mask from the Network LSA. subnet mask from the Network LSA.
5.12. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration 5.12. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration
Graceful migration from one IGP to another requires coordinated Graceful migration from one IGP to another requires coordinated
operation of both protocols during the migration period. Such operation of both protocols during the migration period. Such
coordination requires identifying a given physical link in both IGPs. coordination requires identifying a given physical link in both IGPs.
The IPv4 Router-ID provides that "glue", which is present in the Node The IPv4 Router-ID provides that "glue", which is present in the Node
Descriptors of the OSPF Link NLRI and in the link attribute of the Descriptors of the OSPF Link NLRI and in the link attribute of the
IS-IS Link NLRI. IS-IS Link NLRI.
Consider a point-to-point link between two routers, A and B, that Consider a point-to-point link between two routers, A and B, which
initially were OSPFv2-only routers and then IS-IS is enabled on them. initially were OSPFv2-only routers and then had IS-IS enabled on
Node A has IPv4 Router-ID and ISO-ID; node B has IPv4 Router-ID, IPv6 them. Node A has IPv4 Router-ID and ISO-ID; node B has IPv4 Router-
Router-ID, and ISO-ID. Each protocol generates one Link NLRI for the ID, IPv6 Router-ID, and ISO-ID. Each protocol generates one Link
link (A, B), both of which are carried by BGP-LS. The OSPFv2 Link NLRI for the link (A, B), both of which are carried by BGP-LS. The
NLRI for the link is encoded with the IPv4 Router-ID of nodes A and B OSPFv2 Link NLRI for the link is encoded with the IPv4 Router-ID of
in the local and remote Node Descriptors, respectively. The IS-IS nodes A and B in the local and remote Node Descriptors, respectively.
Link NLRI for the link is encoded with the ISO-ID of nodes A and B in The IS-IS Link NLRI for the link is encoded with the ISO-ID of nodes
the local and remote Node Descriptors, respectively. In addition, A and B in the local and remote Node Descriptors, respectively. In
the BGP-LS Attribute of the IS-IS Link NLRI contains the TLV type addition, the BGP-LS Attribute of the IS-IS Link NLRI contains the
1028 containing the IPv4 Router-ID of node A, TLV type 1030 TLV type 1028 containing the IPv4 Router-ID of node A, TLV type 1030
containing the IPv4 Router-ID of node B, and TLV type 1031 containing containing the IPv4 Router-ID of node B, and TLV type 1031 containing
the IPv6 Router-ID of node B. In this case, by using IPv4 Router-ID, the IPv6 Router-ID of node B. In this case, by using IPv4 Router-ID,
the link (A, B) can be identified in both the IS-IS and OSPF the link (A, B) can be identified in both the IS-IS and OSPF
protocols. protocols.
6. Link to Path Aggregation 6. Link to Path Aggregation
Distribution of all links available on the global Internet is Distribution of all links available on the global Internet is
certainly possible; however, it is not desirable from a scaling and certainly possible; however, it is not desirable from a scaling and
privacy point of view. Therefore, an implementation may support a privacy point of view. Therefore, an implementation may support a
skipping to change at page 47, line 39 skipping to change at line 2065
aggregated set of link properties between a pair of non-adjacent aggregated set of link properties between a pair of non-adjacent
nodes. The actual methods to compute the path properties (of nodes. The actual methods to compute the path properties (of
bandwidth, metric, etc.) are outside the scope of this document. The bandwidth, metric, etc.) are outside the scope of this document. The
decision of whether to advertise all specific links or aggregated decision of whether to advertise all specific links or aggregated
links is an operator's policy choice. To highlight the varying links is an operator's policy choice. To highlight the varying
levels of exposure, the following deployment examples are discussed. levels of exposure, the following deployment examples are discussed.
6.1. Example: No Link Aggregation 6.1. Example: No Link Aggregation
Consider Figure 34. Both AS1 and AS2 operators want to protect their Consider Figure 34. Both AS1 and AS2 operators want to protect their
inter-AS {R1, R3}, {R2, R4} links using RSVP-FRR LSPs. If R1 wants inter-AS {R1, R3}, {R2, R4} links using RSVP - Fast Reroute (RSVP-
to compute its link-protection LSP to R3, it needs to "see" an FRR) LSPs. If R1 wants to compute its link-protection LSP to R3, it
alternate path to R3. Therefore, the AS2 operator exposes its needs to "see" an alternate path to R3. Therefore, the AS2 operator
topology. All BGP-TE-enabled routers in AS1 "see" the full topology exposes its topology. All BGP-TE-enabled routers in AS1 "see" the
of AS2 and therefore can compute a backup path. Note that the full topology of AS2 and therefore can compute a backup path. Note
computing router decides if the direct link between {R3, R4} or the that the computing router decides if the direct link between {R3, R4}
{R4, R5, R3} path is used. or the {R4, R5, R3} path is used.
AS1 : AS2 AS1 : AS2
: :
R1-------R3 R1-------R3
| : | \ | : | \
| : | R5 | : | R5
| : | / | : | /
R2-------R4 R2-------R4
: :
: :
skipping to change at page 49, line 19 skipping to change at line 2127
| : : vR0 | : : vR0
| : : / | : : /
R2-------R4----- R2-------R4-----
: : : :
: : : :
Figure 36: Multi-AS Aggregation Figure 36: Multi-AS Aggregation
7. IANA Considerations 7. IANA Considerations
As this document obsoletes [RFC7752] and [RFC9029], IANA is requested As this document obsoletes [RFC7752] and [RFC9029], IANA has updated
to change all registration information that references those all registration information that references those documents to
documents to instead reference this document. instead reference this document.
IANA has assigned address family number 16388 (BGP-LS) in the IANA has assigned address family number 16388 (BGP-LS) in the
"Address Family Numbers" registry. "Address Family Numbers" registry.
IANA has assigned SAFI values 71 (BGP-LS) and 72 (BGP-LS-VPN) in the IANA has assigned SAFI values 71 (BGP-LS) and 72 (BGP-LS-VPN) in the
"SAFI Values" registry under the "Subsequent Address Family "SAFI Values" registry under the "Subsequent Address Family
Identifiers (SAFI) Parameters" registry group. Identifiers (SAFI) Parameters" registry group.
IANA has assigned value 29 (BGP-LS Attribute) in the "BGP Path IANA has assigned value 29 (BGP-LS Attribute) in the "BGP Path
Attributes" registry under the "Border Gateway Protocol (BGP) Attributes" registry under the "Border Gateway Protocol (BGP)
skipping to change at page 49, line 44 skipping to change at line 2152
IANA has created a "Border Gateway Protocol - Link-State (BGP-LS) IANA has created a "Border Gateway Protocol - Link-State (BGP-LS)
Parameters" registry group at <https://www.iana.org/assignments/bgp- Parameters" registry group at <https://www.iana.org/assignments/bgp-
ls-parameters>. ls-parameters>.
This section also incorporates all the changes to the allocation This section also incorporates all the changes to the allocation
procedures for the BGP-LS IANA registry group as well as the procedures for the BGP-LS IANA registry group as well as the
guidelines for designated experts introduced by [RFC9029]. guidelines for designated experts introduced by [RFC9029].
7.1. BGP-LS Registries 7.1. BGP-LS Registries
All of the registries listed in the following subsections are BGP-LS All of the registries listed in the following subsections are
specific and are accessible under this registry. specific to BGP-LS and are accessible under this registry.
7.1.1. BGP-LS NLRI Types Registry 7.1.1. BGP-LS NLRI Types Registry
The "BGP-LS NLRI Types" registry has been set up for assignment for The "BGP-LS NLRI Types" registry has been set up for assignment for
the two-octet sized code-points for BGP-LS NLRI types and populated the two-octet-sized code points for BGP-LS NLRI types and populated
with the values shown below: with the values shown below:
+=============+===========================+=================+ +=============+===========================+===========+
| Type | NLRI Type | Reference | | Type | NLRI Type | Reference |
+=============+===========================+=================+ +=============+===========================+===========+
| 0 | Reserved | [This document] | | 0 | Reserved | RFC 9552 |
+-------------+---------------------------+-----------------+ +-------------+---------------------------+-----------+
| 1 | Node NLRI | [This document] | | 1 | Node NLRI | RFC 9552 |
+-------------+---------------------------+-----------------+ +-------------+---------------------------+-----------+
| 2 | Link NLRI | [This document] | | 2 | Link NLRI | RFC 9552 |
+-------------+---------------------------+-----------------+ +-------------+---------------------------+-----------+
| 3 | IPv4 Topology Prefix NLRI | [This document] | | 3 | IPv4 Topology Prefix NLRI | RFC 9552 |
+-------------+---------------------------+-----------------+ +-------------+---------------------------+-----------+
| 4 | IPv6 Topology Prefix NLRI | [This document] | | 4 | IPv6 Topology Prefix NLRI | RFC 9552 |
+-------------+---------------------------+-----------------+ +-------------+---------------------------+-----------+
| 65000-65535 | Private Use | [This document] | | 65000-65535 | Private Use | RFC 9552 |
+-------------+---------------------------+-----------------+ +-------------+---------------------------+-----------+
Table 12: BGP-LS NLRI Types Table 12: BGP-LS NLRI Types
A range is reserved for Private Use [RFC8126]. All other allocations A range is reserved for Private Use [RFC8126]. All other allocations
within the registry are to be made using the "Expert Review" policy within the registry are to be made using the "Expert Review" policy
[RFC8126] that requires documentation of the proposed use of the [RFC8126], which requires documentation of the proposed use of the
allocated value and approval by the Designated Expert assigned by the allocated value and approval by the designated expert assigned by the
IESG. IESG.
7.1.2. BGP-LS Protocol-IDs Registry 7.1.2. BGP-LS Protocol-IDs Registry
The "BGP-LS Protocol-IDs" registry has been set up for assignment for The "BGP-LS Protocol-IDs" registry has been set up for assignment for
the one-octet sized code-points for BGP-LS Protocol-IDs and populated the one-octet-sized code points for BGP-LS Protocol-IDs and populated
with the values shown below: with the values shown below:
+=============+==================================+=================+ +=============+==================================+===========+
| Protocol-ID | NLRI information source protocol | Reference | | Protocol-ID | NLRI information source protocol | Reference |
+=============+==================================+=================+ +=============+==================================+===========+
| 0 | Reserved | [This document] | | 0 | Reserved | RFC 9552 |
+-------------+----------------------------------+-----------------+ +-------------+----------------------------------+-----------+
| 1 | IS-IS Level 1 | [This document] | | 1 | IS-IS Level 1 | RFC 9552 |
+-------------+----------------------------------+-----------------+ +-------------+----------------------------------+-----------+
| 2 | IS-IS Level 2 | [This document] | | 2 | IS-IS Level 2 | RFC 9552 |
+-------------+----------------------------------+-----------------+ +-------------+----------------------------------+-----------+
| 3 | OSPFv2 | [This document] | | 3 | OSPFv2 | RFC 9552 |
+-------------+----------------------------------+-----------------+ +-------------+----------------------------------+-----------+
| 4 | Direct | [This document] | | 4 | Direct | RFC 9552 |
+-------------+----------------------------------+-----------------+ +-------------+----------------------------------+-----------+
| 5 | Static configuration | [This document] | | 5 | Static configuration | RFC 9552 |
+-------------+----------------------------------+-----------------+ +-------------+----------------------------------+-----------+
| 6 | OSPFv3 | [This document] | | 6 | OSPFv3 | RFC 9552 |
+-------------+----------------------------------+-----------------+ +-------------+----------------------------------+-----------+
| 200-255 | Private Use | [This document] | | 200-255 | Private Use | RFC 9552 |
+-------------+----------------------------------+-----------------+ +-------------+----------------------------------+-----------+
Table 13: BGP-LS Protocol-IDs Table 13: BGP-LS Protocol-IDs
A range is reserved for Private Use [RFC8126]. All other allocations A range is reserved for Private Use [RFC8126]. All other allocations
within the registry are to be made using the "Expert Review" policy within the registry are to be made using the "Expert Review" policy
[RFC8126] that requires documentation of the proposed use of the [RFC8126], which requires documentation of the proposed use of the
allocated value and approval by the Designated Expert assigned by the allocated value and approval by the designated expert assigned by the
IESG. IESG.
7.1.3. BGP-LS Well-Known Instance-IDs Registry 7.1.3. BGP-LS Well-Known Instance-IDs Registry
The "BGP-LS Well-Known Instance-IDs" registry that was set up via The "BGP-LS Well-Known Instance-IDs" registry that was set up via
[RFC7752] is no longer required. IANA is requested to mark this [RFC7752] is no longer required. IANA has marked this registry
registry as obsolete and to change its registration procedure to obsolete and changed its registration procedure to "registry closed".
"registry closed".
7.1.4. BGP-LS Node Flags Registry 7.1.4. BGP-LS Node Flags Registry
The "BGP-LS Node Flags" registry is requested to be created for the The "BGP-LS Node Flags" registry has been created for the one-octet-
one octet-sized flags field of the Node Flag Bits TLV (1024) and sized flags field of the Node Flag Bits TLV (1024) and populated with
populated with the initial values shown below: the initial values shown below:
+=====+======================+=================+ +=====+======================+===========+
| Bit | Description | Reference | | Bit | Description | Reference |
+=====+======================+=================+ +=====+======================+===========+
| 0 | Overload Bit (O-bit) | [This document] | | 0 | Overload Bit (O-bit) | RFC 9552 |
+-----+----------------------+-----------------+ +-----+----------------------+-----------+
| 1 | Attached Bit (A-bit) | [This document] | | 1 | Attached Bit (A-bit) | RFC 9552 |
+-----+----------------------+-----------------+ +-----+----------------------+-----------+
| 2 | External Bit (E-bit) | [This document] | | 2 | External Bit (E-bit) | RFC 9552 |
+-----+----------------------+-----------------+ +-----+----------------------+-----------+
| 3 | ABR Bit (B-bit) | [This document] | | 3 | ABR Bit (B-bit) | RFC 9552 |
+-----+----------------------+-----------------+ +-----+----------------------+-----------+
| 4 | Router Bit (R-bit) | [This document] | | 4 | Router Bit (R-bit) | RFC 9552 |
+-----+----------------------+-----------------+ +-----+----------------------+-----------+
| 5 | V6 Bit (V-bit) | [This document] | | 5 | V6 Bit (V-bit) | RFC 9552 |
+-----+----------------------+-----------------+ +-----+----------------------+-----------+
| 6-7 | Unassigned | [This document] | | 6-7 | Unassigned | |
+-----+----------------------+-----------------+ +-----+----------------------+-----------+
Table 14: BGP-LS Node Flags Table 14: BGP-LS Node Flags
Allocations within the registry are to be made using the "Expert Allocations within the registry are to be made using the "Expert
Review" policy [RFC8126] that requires documentation of the proposed Review" policy [RFC8126], which requires documentation of the
use of the allocated value and approval by the Designated Expert proposed use of the allocated value and approval by the designated
assigned by the IESG. expert assigned by the IESG.
7.1.5. BGP-LS MPLS Protocol Mask Registry 7.1.5. BGP-LS MPLS Protocol Mask Registry
The "BGP-LS MPLS Protocol Mask" registry is requested to be created The "BGP-LS MPLS Protocol Mask" registry has been created for the
for the one octet-sized flags field of the MPLS Protocol Mask TLV one-octet-sized flags field of the MPLS Protocol Mask TLV (1094) and
(1094) and populated with the initial values shown below: populated with the initial values shown below:
+=====+===========================================+=================+ +=====+===========================================+===========+
| Bit | Description | Reference | | Bit | Description | Reference |
+=====+===========================================+=================+ +=====+===========================================+===========+
| 0 | Label Distribution Protocol (L-bit) | [This document] | | 0 | Label Distribution Protocol (L-bit) | RFC 9552 |
+-----+-------------------------------------------+-----------------+ +-----+-------------------------------------------+-----------+
| 1 | Extension to RSVP for LSP Tunnels | [This document] | | 1 | Extension to RSVP for LSP Tunnels (R-bit) | RFC 9552 |
| | (R-bit) | | +-----+-------------------------------------------+-----------+
+-----+-------------------------------------------+-----------------+ | 2-7 | Unassigned | |
| 2-7 | Unassigned | [This document] | +-----+-------------------------------------------+-----------+
+-----+-------------------------------------------+-----------------+
Table 15: BGP-LS MPLS Protocol Mask Table 15: BGP-LS MPLS Protocol Mask
Allocations within the registry are to be made using the "Expert Allocations within the registry are to be made using the "Expert
Review" policy [RFC8126] that requires documentation of the proposed Review" policy [RFC8126], which requires documentation of the
use of the allocated value and approval by the Designated Expert proposed use of the allocated value and approval by the designated
assigned by the IESG. expert assigned by the IESG.
7.1.6. BGP-LS IGP Prefix Flags Registry 7.1.6. BGP-LS IGP Prefix Flags Registry
The "BGP-LS IGP Prefix Flags" registry is requested to be created for The "BGP-LS IGP Prefix Flags" registry has been created for the one-
the one octet-sized flags field of the IGP Flags TLV (1152) and octet-sized flags field of the IGP Flags TLV (1152) and populated
populated with the initial values shown below: with the initial values shown below:
+=====+===================================+=================+ +=====+===================================+===========+
| Bit | Description | Reference | | Bit | Description | Reference |
+=====+===================================+=================+ +=====+===================================+===========+
| 0 | IS-IS Up/Down Bit (D-bit) | [This document] | | 0 | IS-IS Up/Down Bit (D-bit) | RFC 9552 |
+-----+-----------------------------------+-----------------+ +-----+-----------------------------------+-----------+
| 1 | OSPF "no unicast" Bit (N-bit) | [This document] | | 1 | OSPF "no unicast" Bit (N-bit) | RFC 9552 |
+-----+-----------------------------------+-----------------+ +-----+-----------------------------------+-----------+
| 2 | OSPF "local address" Bit (L-bit) | [This document] | | 2 | OSPF "local address" Bit (L-bit) | RFC 9552 |
+-----+-----------------------------------+-----------------+ +-----+-----------------------------------+-----------+
| 3 | OSPF "propagate NSSA" Bit (P-bit) | [This document] | | 3 | OSPF "propagate NSSA" Bit (P-bit) | RFC 9552 |
+-----+-----------------------------------+-----------------+ +-----+-----------------------------------+-----------+
| 4-7 | Unassigned | [This document] | | 4-7 | Unassigned | |
+-----+-----------------------------------+-----------------+ +-----+-----------------------------------+-----------+
Table 16: BGP-LS IGP Prefix Flags Table 16: BGP-LS IGP Prefix Flags
Allocations within the registry are to be made using the "Expert Allocations within the registry are to be made using the "Expert
Review" policy [RFC8126] that requires documentation of the proposed Review" policy [RFC8126], which requires documentation of the
use of the allocated value and approval by the Designated Expert proposed use of the allocated value and approval by the designated
assigned by the IESG. expert assigned by the IESG.
7.1.7. BGP-LS TLVs Registry 7.1.7. BGP-LS TLVs Registry
The "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and The "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and
Attribute TLVs" registry was created via [RFC7752]. This document Attribute TLVs" registry was created via [RFC7752]. Per this
requests IANA to rename that registry to "BGP-LS NLRI and Attribute document, IANA has renamed that registry to "BGP-LS NLRI and
TLVs" and to remove the column for "IS-IS TLV/Sub-TLV". The Attribute TLVs" and removed the column for "IS-IS TLV/Sub-TLV". The
registration procedures are as below: registration procedures are as follows:
+================+================================+ +================+================================+
| TLV Code Point | Registration Process | | TLV Code Point | Registration Process |
+================+================================+ +================+================================+
| 0-255 | Reserved (not to be allocated) | | 0-255 | Reserved (not to be allocated) |
+----------------+--------------------------------+ +----------------+--------------------------------+
| 256-64999 | Expert Review | | 256-64999 | Expert Review |
+----------------+--------------------------------+ +----------------+--------------------------------+
| 65000-65535 | Private Use | | 65000-65535 | Private Use |
+----------------+--------------------------------+ +----------------+--------------------------------+
Table 17: BGP-LS TLVs Registration Process Table 17: BGP-LS TLVs Registration Process
A range is reserved for Private Use [RFC8126]. All other allocations A range is reserved for Private Use [RFC8126]. All other allocations
except for the reserved range within the registry are to be made except for the reserved range within the registry are to be made
using the "Expert Review" policy [RFC8126] that requires using the "Expert Review" policy [RFC8126], which requires
documentation of the proposed use of the allocated value and approval documentation of the proposed use of the allocated value and approval
by the Designated Expert assigned by the IESG. by the designated expert assigned by the IESG.
The registry was pre-populated with the values shown in Table 18 and The registry was pre-populated with the values shown in Table 18, and
the reference for all those allocations should be changed to this the reference for each allocation has been changed to this document
document and the respective section where those TLVs are specified. and the respective section where those TLVs are specified.
7.2. Guidance for Designated Experts 7.2. Guidance for Designated Experts
In all cases of review by the designated expert described here, the In all cases of review by the designated expert described here, the
designated expert is expected to check the clarity of purpose and use designated expert is expected to check the clarity of purpose and use
of the requested code points. The following points apply to the of the requested code points. The following points apply to the
registries discussed in this document: registries discussed in this document:
1. Application for a code point allocation may be made to the 1. Application for a code point allocation may be made to the
designated experts at any time and MUST be accompanied by designated experts at any time and MUST be accompanied by
technical documentation explaining the use of the code point. technical documentation explaining the use of the code point.
Such documentation SHOULD be presented in the form of an Such documentation SHOULD be presented in the form of an
Internet-Draft, but MAY arrive in any form that can be reviewed Internet-Draft but MAY arrive in any form that can be reviewed
and exchanged among reviewers. and exchanged among reviewers.
2. The designated experts SHOULD only consider requests that arise 2. The designated experts SHOULD only consider requests that arise
from Internet-Drafts that have already been accepted as working from Internet-Drafts that have already been accepted as working
group documents or that are planned for progression as AD- group documents or that are planned for progression as AD-
Sponsored documents in the absence of a suitably chartered Sponsored documents in the absence of a suitably chartered
working group. working group.
3. In the case of working group documents, the designated experts 3. In the case of working group documents, the designated experts
MUST check with the working group chairs that there is a MUST check with the working group chairs that there is a
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6. The designated expert MUST ensure that any request for a code 6. The designated expert MUST ensure that any request for a code
point does not conflict with work that is active or already point does not conflict with work that is active or already
published within the IETF. published within the IETF.
7. Once the designated experts have approved, IANA will update the 7. Once the designated experts have approved, IANA will update the
registry by marking the allocated code points with a reference to registry by marking the allocated code points with a reference to
the associated document. the associated document.
8. In the event that the document is a working group document or is 8. In the event that the document is a working group document or is
AD-Sponsored, and that document fails to progress to publication AD-Sponsored and fails to progress to publication as an RFC, the
as an RFC, the working group chairs or AD SHOULD contact IANA to working group chairs or AD SHOULD contact IANA to coordinate
coordinate about marking the code points as deprecated. A about marking the code points as deprecated. A deprecated code
deprecated code point is not marked as allocated for use and is point is not marked as allocated for use and is not available for
not available for allocation in a future document. The WG chairs allocation in a future document. The WG chairs may inform IANA
may inform IANA that a deprecated code point can be completely that a deprecated code point can be completely deallocated (i.e.,
deallocated (i.e., made available for new allocations) at any made available for new allocations) at any time after it has been
time after it has been deprecated if there is a shortage of deprecated if there is a shortage of unallocated code points in
unallocated code points in the registry. the registry.
8. Manageability Considerations 8. Manageability Considerations
This section is structured as recommended in [RFC5706]. This section is structured as recommended in [RFC5706].
8.1. Operational Considerations 8.1. Operational Considerations
8.1.1. Operations 8.1.1. Operations
Existing BGP operational procedures apply. No new operation Existing BGP operational procedures apply. No new operation
skipping to change at page 55, line 44 skipping to change at line 2414
information present in this document carries purely application-level information present in this document carries purely application-level
data that has no immediate impact on the corresponding forwarding data that has no immediate impact on the corresponding forwarding
state computed by BGP. As such, any churn in reachability state computed by BGP. As such, any churn in reachability
information has a different impact than regular BGP updates, which information has a different impact than regular BGP updates, which
need to change the forwarding state for an entire router. need to change the forwarding state for an entire router.
Distribution of the BGP-LS NLRIs SHOULD be handled by dedicated route Distribution of the BGP-LS NLRIs SHOULD be handled by dedicated route
reflectors in most deployments providing a level of isolation and reflectors in most deployments providing a level of isolation and
fault containment between different BGP address families. In the fault containment between different BGP address families. In the
event of dedicated route reflectors not being available, other event of dedicated route reflectors not being available, other
alternate mechanisms like separation of BGP instances or separate BGP alternate mechanisms like separation of BGP instances or separate BGP
sessions (e.g. using different addresses for peering) for Link-State sessions (e.g., using different addresses for peering) for Link-State
information distribution SHOULD be used. information distribution SHOULD be used.
It is RECOMMENDED that operators deploying BGP-LS enable two or more It is RECOMMENDED that operators deploying BGP-LS enable two or more
BGP-LS Producers in each IGP flooding domain to achieve redundancy in BGP-LS Producers in each IGP flooding domain to achieve redundancy in
the origination of link-state information into BGP-LS. It is also the origination of link-state information into BGP-LS. It is also
RECOMMENDED that operators ensure BGP peering designs that ensure RECOMMENDED that operators ensure BGP peering designs that ensure
redundancy in the BGP update propagation paths (e.g., using at least redundancy in the BGP update propagation paths (e.g., using at least
a pair of route reflectors) and ensuring that BGP-LS Consumers are a pair of route reflectors) and ensure that BGP-LS Consumers are
receiving the topology information from at least two BGP-LS Speakers. receiving the topology information from at least two BGP-LS Speakers.
In a multi-domain IGP network, the correct provisioning of the BGP-LS In a multi-domain IGP network, the correct provisioning of the BGP-LS
Instance-IDs on the BGP-LS Producers is required for consistent Instance-IDs on the BGP-LS Producers is required for consistent
reporting of the multi-domain link-state topology. Refer to reporting of the multi-domain link-state topology. Refer to
Section 5.2 for more details. Section 5.2 for more details.
8.1.2. Installation and Initial Setup 8.1.2. Installation and Initial Setup
Configuration parameters defined in Section 8.2.3 SHOULD be Configuration parameters defined in Section 8.2.3 SHOULD be
skipping to change at page 57, line 17 skipping to change at line 2475
Existing BGP procedures apply. In addition, an implementation SHOULD Existing BGP procedures apply. In addition, an implementation SHOULD
allow an operator to: allow an operator to:
* List neighbors with whom the speaker is exchanging Link-State * List neighbors with whom the speaker is exchanging Link-State
NLRIs. NLRIs.
8.2. Management Considerations 8.2. Management Considerations
8.2.1. Management Information 8.2.1. Management Information
The IDR working group has documented and continues to document parts The IDR Working Group has documented and continues to document parts
of the Management Information Base and YANG models for managing and of the Management Information Base and YANG models for managing and
monitoring BGP speakers and the sessions between them. It is monitoring BGP Speakers and the sessions between them. It is
currently believed that the BGP session running BGP-LS is not currently believed that the BGP session running BGP-LS is not
substantially different from any other BGP session and can be managed substantially different from any other BGP session and can be managed
using the same data models. using the same data models.
8.2.2. Fault Management 8.2.2. Fault Management
This section describes the fault management actions, as described in This section describes the fault management actions, as described in
[RFC7606], that are to be performed for the handling of BGP UPDATE [RFC7606], that are to be performed for the handling of BGP UPDATE
messages for BGP-LS. messages for BGP-LS.
A Link-State NLRI MUST NOT be considered malformed or invalid based A Link-State NLRI MUST NOT be considered malformed or invalid based
on the inclusion/exclusion of TLVs or contents of the TLV fields on the inclusion/exclusion of TLVs or contents of the TLV fields
(i.e. semantic errors), as described in Section 5.1 and Section 5.2. (i.e., semantic errors), as described in Sections 5.1 and 5.2.
A BGP-LS Speaker MUST perform the following syntactic validation of A BGP-LS Speaker MUST perform the following syntactic validation of
the Link-State NLRI to determine if it is malformed. the Link-State NLRI to determine if it is malformed.
* The sum of all TLVs lengths found in the BGP MP_REACH_NLRI * The sum of all TLV lengths found in the BGP MP_REACH_NLRI
attribute corresponds to the BGP MP_REACH_NLRI length. attribute corresponds to the BGP MP_REACH_NLRI length.
* The sum of all TLVs lengths found in the BGP MP_UNREACH_NLRI * The sum of all TLV lengths found in the BGP MP_UNREACH_NLRI
attribute corresponds to the BGP MP_UNREACH_NLRI length. attribute corresponds to the BGP MP_UNREACH_NLRI length.
* The sum of all TLVs lengths found in a Link-State NLRI corresponds * The sum of all TLV lengths found in a Link-State NLRI corresponds
to the Total NLRI Length field of all its Descriptors. to the Total NLRI Length field of all its descriptors.
* The length of the TLVs and, when the TLV is recognized then, the * The length of the TLVs and, when the TLV is recognized then, the
length of its sub-TLVs in the NLRI is valid. length of its sub-TLVs in the NLRI are valid.
* The syntactic correctness of the NLRI fields been verified as per * The syntactic correctness of the NLRI fields has been verified as
[RFC7606]. per [RFC7606].
* The rule regarding the ordering of TLVs been followed as described * The rule regarding the ordering of TLVs has been followed as
in Section 5.1. described in Section 5.1.
* For NLRIs carrying either a Local or Remote Node Descriptor TLV, * For NLRIs carrying either a Local or Remote Node Descriptor TLV,
there is not more than one instance of a sub-TLV present. there is not more than one instance of a sub-TLV present.
When the error that is determined allows for the router to skip the When the error that is determined allows for the router to skip the
malformed NLRI(s) and continue the processing of the rest of the BGP malformed NLRI(s) and continue the processing of the rest of the BGP
UPDATE message (e.g. when the TLV ordering rule is violated), then it UPDATE message (e.g., when the TLV ordering rule is violated), then
MUST handle such malformed NLRIs as 'NLRI discard' (i.e., processing it MUST handle such malformed NLRIs as 'NLRI discard' (i.e.,
similar to what is described in section 5.4 of [RFC7606]). In other processing similar to what is described in Section 5.4 of [RFC7606]).
cases, where the error in the NLRI encoding results in the inability In other cases, where the error in the NLRI encoding results in the
to process the BGP UPDATE message (e.g. length related encoding inability to process the BGP UPDATE message (e.g., length-related
errors), then the router SHOULD handle such malformed NLRIs as 'AFI/ encoding errors), then the router SHOULD handle such malformed NLRIs
SAFI disable' when other AFI/SAFI besides BGP-LS are being advertised as 'AFI/SAFI disable' when other AFI/SAFI besides BGP-LS are being
over the same session. Alternately, the router MUST perform a advertised over the same session. Alternately, the router MUST
'session reset' when the session is only being used for BGP-LS or if perform a 'session reset' when the session is only being used for
'AFI/SAFI disable' action is not possible. BGP-LS or if 'AFI/SAFI disable' action is not possible.
A BGP-LS Attribute MUST NOT be considered malformed or invalid based A BGP-LS Attribute MUST NOT be considered malformed or invalid based
on the inclusion/exclusion of TLVs or contents of the TLV fields on the inclusion/exclusion of TLVs or contents of the TLV fields
(i.e. semantic errors), as described in Section 5.1 and Section 5.3. (i.e., semantic errors), as described in Sections 5.1 and 5.3.
A BGP-LS Speaker MUST perform the following syntactic validation of A BGP-LS Speaker MUST perform the following syntactic validation of
the BGP-LS Attribute to determine if it is malformed. the BGP-LS Attribute to determine if it is malformed.
* The sum of all TLVs lengths found in the BGP-LS Attribute * The sum of all TLV lengths found in the BGP-LS Attribute
corresponds to the BGP-LS Attribute length. corresponds to the BGP-LS Attribute length.
* The syntactic correctness of the Attributes (including BGP-LS * The syntactic correctness of the Attributes (including the BGP-LS
Attribute) been verified as per [RFC7606]. Attribute) have been verified as per [RFC7606].
* The length of each TLV and, when the TLV is recognized then, the * The length of each TLV and, when the TLV is recognized then, the
length of its sub-TLVs in the BGP-LS Attribute is valid. length of its sub-TLVs in the BGP-LS Attribute are valid.
When the error that is determined allows for the router to skip the When the error that is determined allows for the router to skip the
malformed BGP-LS Attribute and continue the processing of the rest of malformed BGP-LS Attribute and continue the processing of the rest of
the BGP UPDATE message (e.g. when the BGP-LS Attribute length and the the BGP UPDATE message (e.g., when the BGP-LS Attribute length and
total Path Attribute Length are correct but some TLV/sub-TLV length the total Path Attribute Length are correct but some TLV/sub-TLV
within the BGP-LS Attribute is invalid), then it MUST handle such length within the BGP-LS Attribute is invalid), then it MUST handle
malformed BGP-LS Attribute as 'Attribute Discard'. In other cases, such malformed BGP-LS Attribute as 'Attribute Discard'. In other
where the error in the BGP-LS Attribute encoding results in the cases, where the error in the BGP-LS Attribute encoding results in
inability to process the BGP UPDATE message then the handling is the the inability to process the BGP UPDATE message, the handling is the
same as described above for the malformed NLRI. same as described above for the malformed NLRI.
Note that the 'Attribute Discard' action results in the loss of all Note that the 'Attribute Discard' action results in the loss of all
TLVs in the BGP-LS Attribute and not the removal of a specific TLVs in the BGP-LS Attribute and not the removal of a specific
malformed TLV. The removal of specific malformed TLVs may give a malformed TLV. The removal of specific malformed TLVs may give a
wrong indication to a BGP-LS Consumer of that specific information wrong indication to a BGP-LS Consumer of that specific information
being deleted or not available. being deleted or not available.
When a BGP Speaker receives an UPDATE message with Link-State NLRI(s) When a BGP Speaker receives an UPDATE message with Link-State NLRI(s)
in the MP_REACH_NLRI but without the BGP-LS Attribute, it is most in the MP_REACH_NLRI but without the BGP-LS Attribute, it is most
skipping to change at page 59, line 32 skipping to change at line 2582
An implementation SHOULD log a message for any errors found during An implementation SHOULD log a message for any errors found during
syntax validation for further analysis. syntax validation for further analysis.
A BGP-LS Propagator, even when it has a coexisting BGP-LS Consumer on A BGP-LS Propagator, even when it has a coexisting BGP-LS Consumer on
the same node, should not perform semantic validation of the Link- the same node, should not perform semantic validation of the Link-
State NLRI or the BGP-LS Attribute to determine if it is malformed or State NLRI or the BGP-LS Attribute to determine if it is malformed or
invalid. Some types of semantic validation that are not to be invalid. Some types of semantic validation that are not to be
performed by a BGP-LS Propagator are as follows (and this is not to performed by a BGP-LS Propagator are as follows (and this is not to
be considered as an exhaustive list): be considered as an exhaustive list):
* presence of mandatory TLV * presence of a mandatory TLV
* the length of a fixed-length TLV correct or the length of a * the length of a fixed-length TLV is correct or the length of a
variable length TLV is valid or permissible variable length TLV is valid or permissible
* the values of TLV fields are valid or permissible * the values of TLV fields are valid or permissible
* the inclusion and use of TLVs/sub-TLVs with specific Link-State * the inclusion and use of TLVs/sub-TLVs with specific Link-State
NLRI types is valid NLRI types is valid
Each TLV may indicate the valid and permissible values and their Each TLV may indicate the valid and permissible values and their
semantics that can be used only by a BGP-LS Consumer for its semantic semantics that can be used only by a BGP-LS Consumer for its semantic
validation. However, the handling of any errors may be specific to validation. However, the handling of any errors may be specific to
skipping to change at page 60, line 21 skipping to change at line 2619
Base (RIB). Base (RIB).
An implementation SHOULD allow the operator to create abstracted An implementation SHOULD allow the operator to create abstracted
topologies that are advertised to neighbors and create different topologies that are advertised to neighbors and create different
abstractions for different neighbors. abstractions for different neighbors.
An implementation MUST allow the operator to configure an 8-octet An implementation MUST allow the operator to configure an 8-octet
BGP-LS Instance-ID. Refer to Section 5.2 for guidance to the BGP-LS Instance-ID. Refer to Section 5.2 for guidance to the
operator for the configuration of BGP-LS Instance-ID. operator for the configuration of BGP-LS Instance-ID.
An implementation SHOULD allow the operator to configure ASN and BGP- An implementation SHOULD allow the operator to configure Autonomous
LS identifiers (refer to Section 5.2.1.4). System Number (ASN) and BGP-LS identifiers (refer to
Section 5.2.1.4).
An implementation SHOULD allow the operator to configure limiting of An implementation SHOULD allow the operator to configure limiting the
maximum size of a BGP-LS UPDATE message to 4096 bytes on a BGP-LS maximum size of a BGP-LS UPDATE message to 4096 bytes on a BGP-LS
Producer or to allow larger values when they know that [RFC8654] is Producer or to allow larger values when they know that [RFC8654] is
supported on all BGP-LS Speakers. supported on all BGP-LS Speakers.
8.2.4. Accounting Management 8.2.4. Accounting Management
Not Applicable. Not Applicable.
8.2.5. Performance Management 8.2.5. Performance Management
skipping to change at page 61, line 33 skipping to change at line 2681
| | Identifiers | | | | Identifiers | |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 259 | IPv4 interface address | Section 5.2.2 | | 259 | IPv4 interface address | Section 5.2.2 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 260 | IPv4 neighbor address | Section 5.2.2 | | 260 | IPv4 neighbor address | Section 5.2.2 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 261 | IPv6 interface address | Section 5.2.2 | | 261 | IPv6 interface address | Section 5.2.2 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 262 | IPv6 neighbor address | Section 5.2.2 | | 262 | IPv6 neighbor address | Section 5.2.2 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 263 | Multi-Topology ID | Section 5.2.2.1 | | 263 | Multi-Topology | Section 5.2.2.1 |
| | Identifier | |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 264 | OSPF Route Type | Section 5.2.3 | | 264 | OSPF Route Type | Section 5.2.3.1 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 265 | IP Reachability | Section 5.2.3 | | 265 | IP Reachability | Section 5.2.3.2 |
| | Information | | | | Information | |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 512 | Autonomous System | Section 5.2.1.4 | | 512 | Autonomous System | Section 5.2.1.4 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 513 | BGP-LS Identifier | Section 5.2.1.4 | | 513 | BGP-LS Identifier | Section 5.2.1.4 |
| | (deprecated) | | | | (deprecated) | |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 514 | OSPF Area-ID | Section 5.2.1.4 | | 514 | OSPF Area-ID | Section 5.2.1.4 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 515 | IGP Router-ID | Section 5.2.1.4 | | 515 | IGP Router-ID | Section 5.2.1.4 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1024 | Node Flag Bits | Section 5.3.1.1 | | 1024 | Node Flag Bits | Section 5.3.1.1 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1025 | Opaque Node Attribute | Section 5.3.1.5 | | 1025 | Opaque Node Attribute | Section 5.3.1.5 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1026 | Node Name | Section 5.3.1.3 | | 1026 | Node Name | Section 5.3.1.3 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1027 | IS-IS Area Identifier | Section 5.3.1.2 | | 1027 | IS-IS Area Identifier | Section 5.3.1.2 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1028 | IPv4 Router-ID of Local | Section 5.3.1.4 / | | 1028 | IPv4 Router-ID of Local | Sections 5.3.1.4 |
| | Node | Section 5.3.2.1 | | | Node | and 5.3.2.1 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1029 | IPv6 Router-ID of Local | Section 5.3.1.4 / | | 1029 | IPv6 Router-ID of Local | Sections 5.3.1.4 |
| | Node | Section 5.3.2.1 | | | Node | and 5.3.2.1 |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1030 | IPv4 Router-ID of | Section 5.3.2.1 | | 1030 | IPv4 Router-ID of | Section 5.3.2.1 |
| | Remote Node | | | | Remote Node | |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1031 | IPv6 Router-ID of | Section 5.3.2.1 | | 1031 | IPv6 Router-ID of | Section 5.3.2.1 |
| | Remote Node | | | | Remote Node | |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
| 1088 | Administrative group | Section 5.3.2 | | 1088 | Administrative group | Section 5.3.2 |
| | (color) | | | | (color) | |
+----------------+-------------------------+-------------------+ +----------------+-------------------------+-------------------+
skipping to change at page 63, line 18 skipping to change at line 2764
Table 18: Summary Table of TLV/Sub-TLV Code Points Table 18: Summary Table of TLV/Sub-TLV Code Points
10. Security Considerations 10. Security Considerations
Procedures and protocol extensions defined in this document do not Procedures and protocol extensions defined in this document do not
affect the BGP security model. See the Security Considerations affect the BGP security model. See the Security Considerations
section of [RFC4271] for a discussion of BGP security. Also, refer section of [RFC4271] for a discussion of BGP security. Also, refer
to [RFC4272] and [RFC6952] for analysis of security issues for BGP. to [RFC4272] and [RFC6952] for analysis of security issues for BGP.
The operator should ensure that a BGP-LS speaker does not accept The operator should ensure that a BGP-LS Speaker does not accept
UPDATE messages from a peer that only provides information to a BGP- UPDATE messages from a peer that only provides information to a BGP-
LS Consumer by using the policy configuration options discussed in LS Consumer by using the policy configuration options discussed in
Section 8.2.3 and Section 8.2.6. Generally, an operator is aware of Sections 8.2.3 and 8.2.6. Generally, an operator is aware of the
the BGP-LS speaker's role and link-state peerings. Therefore, the BGP-LS Speaker's role and link-state peerings. Therefore, the
operator can protect the BGP-LS speaker from peers sending updates operator can protect the BGP-LS Speaker from peers sending updates
that may represent erroneous information, feedback loops, or false that may represent erroneous information, feedback loops, or false
input. input.
An error or tampering of the link-state information that is An error or tampering of the link-state information that is
originated into BGP-LS and propagated through the network for use by originated into BGP-LS and propagated through the network for use by
BGP-LS Consumers applications can result in the malfunction of those BGP-LS Consumers applications can result in the malfunction of those
applications. Some examples of such risks are the origination of applications. Some examples of such risks are the origination of
incorrect information that is not present or consistent with the IGP incorrect information that is not present or consistent with the IGP
LSDB at the BGP-LS Producer, incorrect ordering of TLVs in the NLRI LSDB at the BGP-LS Producer, incorrect ordering of TLVs in the NLRI,
or inconsistent origination from multiple BGP-LS Producers and or inconsistent origination from multiple BGP-LS Producers and
updates to either the NLRI or BGP-LS Attribute during propagation updates to either the NLRI or BGP-LS Attribute during propagation
(including discarding due to errors). These are not new risks from a (including discarding due to errors). These are not new risks from a
BGP protocol perspective, however, in the case of BGP-LS impact BGP protocol perspective; however, in the case of BGP-LS, impact
reflects on the consumer applications instead of BGP routing reflects on the consumer applications instead of BGP routing
functionalities. functionalities.
Additionally, it may be considered that the export of link-state and Additionally, it may be considered that the export of link-state and
TE information as described in this document constitutes a risk to TE information as described in this document constitutes a risk to
confidentiality of mission-critical or commercially sensitive confidentiality of mission-critical or commercially sensitive
information about the network. BGP peerings are not automatic and information about the network. BGP peerings are not automatic and
require configuration; thus, it is the responsibility of the network require configuration; thus, it is the responsibility of the network
operator to ensure that only trusted BGP Speakers are configured to operator to ensure that only trusted BGP Speakers are configured to
receive such information. Similar security considerations also arise receive such information. Similar security considerations also arise
on the interface between BGP Speaker and BGP-LS Consumers, but their on the interface between BGP Speakers and BGP-LS Consumers, but their
discussion is outside the scope of this document. discussion is outside the scope of this document.
11. Contributors 11. References
The following persons contributed significant text to RFC7752 and
this document. They should be considered co-authors.
Hannes Gredler
Rtbrick
Email: hannes@rtbrick.com
Jan Medved
Cisco Systems Inc.
USA
Email: jmedved@cisco.com
Stefano Previdi
Huawei Technologies
Italy
Email: stefano@previdi.net
Adrian Farrel
Old Dog Consulting
Email: adrian@olddog.co.uk
Saikat Ray
Individual
USA
Email: raysaikat@gmail.com
12. Acknowledgements
This document update to the BGP-LS specification [RFC7752] is a
result of feedback and inputs from the discussions in the IDR working
group. It also incorporates certain details and clarifications based
on implementation and deployment experience with BGP-LS.
Cengiz Alaettinoglu and Parag Amritkar brought forward the need to
clarify the advertisement of a LAN subnet for OSPF.
We would like to thank Balaji Rajagopalan, Srihari Sangli, Shraddha
Hegde, Andrew Stone, Jeff Tantsura, Acee Lindem, Les Ginsberg, Jie
Dong, Aijun Wang, Nandan Saha, Joel Halpern, and Gyan Mishra for
their review and feedback on this document. Thanks to Tom Petch for
his review and comments on the IANA Considerations section. Would
also like to thank Jeffrey Haas for his detailed shepherd review and
inputs for improving the document.
The detailed AD review by Alvaro Retana and his suggestions have
helped improve this document significantly.
We would like to thank Robert Varga for his significant contribution
to RFC7752.
We would like to thank Nischal Sheth, Alia Atlas, David Ward, Derek
Yeung, Murtuza Lightwala, John Scudder, Kaliraj Vairavakkalai, Les
Ginsberg, Liem Nguyen, Manish Bhardwaj, Matt Miller, Mike Shand,
Peter Psenak, Rex Fernando, Richard Woundy, Steven Luong, Tamas
Mondal, Waqas Alam, Vipin Kumar, Naiming Shen, Carlos Pignataro,
Balaji Rajagopalan, Yakov Rekhter, Alvaro Retana, Barry Leiba, and
Ben Campbell for their comments on RFC7752.
13. References
13.1. Normative References 11.1. Normative References
[ENTNUM] IANA, "Private Enterprise Numbers", [ENTNUM] IANA, "Private Enterprise Numbers (PENs)",
<https://www.iana.org/assignments/enterprise-numbers/>. <https://www.iana.org/assignments/enterprise-numbers/>.
[ISO10589] International Organization for Standardization, [ISO10589] ISO, "Information technology - Telecommunications and
"Intermediate System to Intermediate System intra-domain information exchange between systems - Intermediate System
routeing information exchange protocol for use in to Intermediate System intra-domain routeing information
conjunction with the protocol for providing the exchange protocol for use in conjunction with the protocol
connectionless-mode network service (ISO 8473)", ISO/ for providing the connectionless-mode network service (ISO
IEC 10589, November 2002. 8473)", ISO/IEC 10589:2002, November 2002.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998, DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>. <https://www.rfc-editor.org/info/rfc2328>.
skipping to change at page 68, line 18 skipping to change at line 2943
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA) F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>. 2018, <https://www.rfc-editor.org/info/rfc8362>.
[RFC8654] Bush, R., Patel, K., and D. Ward, "Extended Message [RFC8654] Bush, R., Patel, K., and D. Ward, "Extended Message
Support for BGP", RFC 8654, DOI 10.17487/RFC8654, October Support for BGP", RFC 8654, DOI 10.17487/RFC8654, October
2019, <https://www.rfc-editor.org/info/rfc8654>. 2019, <https://www.rfc-editor.org/info/rfc8654>.
13.2. Informative References 11.2. Informative References
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.
J., and E. Lear, "Address Allocation for Private J., and E. Lear, "Address Allocation for Private
Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918, Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918,
February 1996, <https://www.rfc-editor.org/info/rfc1918>. February 1996, <https://www.rfc-editor.org/info/rfc1918>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006, RFC 4272, DOI 10.17487/RFC4272, January 2006,
<https://www.rfc-editor.org/info/rfc4272>. <https://www.rfc-editor.org/info/rfc4272>.
skipping to change at page 70, line 11 skipping to change at line 3032
MPLS and GMPLS Traffic Engineering", RFC 9346, MPLS and GMPLS Traffic Engineering", RFC 9346,
DOI 10.17487/RFC9346, February 2023, DOI 10.17487/RFC9346, February 2023,
<https://www.rfc-editor.org/info/rfc9346>. <https://www.rfc-editor.org/info/rfc9346>.
Appendix A. Changes from RFC 7752 Appendix A. Changes from RFC 7752
This section lists the high-level changes from RFC 7752 and provides This section lists the high-level changes from RFC 7752 and provides
reference to the document sections wherein those have been reference to the document sections wherein those have been
introduced. introduced.
1. Updated the Figure 1 in Section 1 and added Section 3 to 1. Updated Figure 1 in Section 1 and added Section 3 to illustrate
illustrate the different roles of a BGP implementation in the different roles of a BGP implementation in conveying link-
conveying link-state information. state information.
2. Clarified aspects related to advertisement of link-state 2. Clarified aspects related to advertisement of link-state
information from IGPs into BGP-LS in Section 4. information from IGPs into BGP-LS in Section 4.
3. In Section 5.1, clarification about the TLV handling aspects 3. In Section 5.1, clarified aspects about TLV handling that apply
that apply to both the NLRI and BGP-LS Attribute parts and those to both the NLRI and BGP-LS Attribute parts as well as those
that are applicable only for the NLRI portion. An that are applicable only for the NLRI portion. An
implementation may have missed the part about the handling of implementation may have missed the part about the handling of an
unknown TLV and so, based on [RFC7606] guidelines, might discard unknown TLV and so, based on [RFC7606] guidelines, might discard
the unknown NLRI types. This aspect is now unambiguously the unknown NLRI types. This aspect is now unambiguously
clarified in Section 5.2. Also, the TLVs in the BGP-LS clarified in Section 5.2. Also, the TLVs in the BGP-LS
Attribute that are not ordered are not to be considered Attribute that are not ordered are not to be considered
malformed. malformed.
4. Clarification of mandatory and optional TLVs in both NLRI and 4. Clarified aspects of mandatory and optional TLVs in both NLRI
BGP-LS Attribute portions all through the document. and BGP-LS Attribute portions all through the document.
5. Handling of large size of BGP-LS Attribute with growth in BGP-LS 5. In Section 5.3, the handling of a large-sized BGP-LS Attribute
information is explained in Section 5.3 along with mitigation of with growth in BGP-LS information is explained along with
errors arising out of it. mitigation of errors arising out of it.
6. Clarified that the document describes the NLRI descriptor TLVs 6. Clarified that the document describes the NLRI descriptor TLVs
for the protocols and NLRI types specified in this document and for the protocols and NLRI types specified in this document as
future BGP-LS extensions must describe the same for other well as future BGP-LS extensions must describe the same for
protocols and NLRI types that they introduce. other protocols and NLRI types that they introduce.
7. Clarification on the use of the Identifier field in the Link- 7. In Section 5.2, clarified the use of the Identifier field in the
State NLRI in Section 5.2 is provided. It was defined Link-State NLRI. It was defined ambiguously to refer to only
ambiguously to refer to only multi-instance IGP on a single link multi-instance IGP on a single link while it can also be used
while it can also be used for multiple IGP protocol instances on for multiple IGP protocol instances on a router. The IANA
a router. The IANA registry is accordingly being removed. registry is accordingly being removed.
8. The BGP-LS Identifier TLV in the Node Descriptors has been 8. The BGP-LS Identifier TLV in the Node Descriptors has been
deprecated. Its use was not well specified by [RFC7752] and deprecated. Its use was not well specified by [RFC7752], and
there has been some amount of confusion between implementators there has been some amount of confusion between implementors on
on its usage for identification of IGP domains as against the its usage for identification of IGP domains as against the use
use of the Identifier field carrying the BGP-LS Instance-ID when of the Identifier field carrying the BGP-LS Instance-ID when
running multiple instances of IGP routing protocols. The running multiple instances of IGP routing protocols. The
original purpose of the BGP-LS Identifier was that, in original purpose of the BGP-LS Identifier was that, in
conjunction with Autonomous System Number (ASN), it would conjunction with the ASN, it would uniquely identify the BGP-LS
uniquely identify the BGP-LS domain and that the combination of domain and that the combination of ASN and BGP-LS ID would be
ASN and BGP-LS ID would be globally unique. However, the BGP-LS globally unique. However, the BGP-LS Instance-ID carried in the
Instance-ID carried in the Identifier field in the fixed part of Identifier field in the fixed part of the NLRI also provides a
the NLRI also provides a similar functionality. Hence, the similar functionality. Hence, the inclusion of the BGP-LS
inclusion of the BGP-LS Identifier TLV is not necessary. If Identifier TLV is not necessary. If advertised, all BGP-LS
advertised, all BGP-LS speakers within an IGP flooding-set (set Speakers within an IGP flooding-set (set of IGP nodes within
of IGP nodes within which an LSP/LSA is flooded) had to use the which an LSP/LSA is flooded) had to use the same (ASN, BGP-LS
same (ASN, BGP-LS ID) tuple and if an IGP domain consists of ID) tuple, and if an IGP domain consists of multiple flooding-
multiple flooding-sets, then all BGP-LS speakers within the IGP sets, then all BGP-LS Speakers within the IGP domain had to use
domain had to use the same (ASN, BGP-LS ID) tuple. the same (ASN, BGP-LS ID) tuple.
9. Clarification that the Area-ID TLV is mandatory in the Node 9. Clarified that the Area-ID TLV is mandatory in the Node
Descriptor for the origination of information from OSPF except Descriptor for the origination of information from OSPF except
for when sourcing information from AS-scope LSAs where this TLV for when sourcing information from AS-scope LSAs where this TLV
is not applicable. Also clarified on the IS-IS area and area is not applicable. Also clarified the IS-IS area and area
addresses. addresses.
10. Moved MT-ID TLV from the Node Descriptor section to under the 10. Moved the MT-ID TLV from the Node Descriptor section to under
Link Descriptor section since it is not a Node Descriptor sub- the Link Descriptor section since it is not a Node Descriptor
TLV. Fixed the ambiguity in the encoding of OSPF MT-ID in this sub-TLV. Fixed the ambiguity in the encoding of OSPF MT-ID in
TLV. Updated the IS-IS specification reference section and this TLV. Updated the IS-IS specification reference section and
describe the differences in the applicability of the R flags described the differences in the applicability of the R flags
when MT-ID TLV is used as link descriptor TLV and Prefix when the MT-ID TLV is used as the Link Descriptor TLV and Prefix
Attribute TLV. MT-ID TLV use is now elevated to SHOULD when it Attribute TLV. The MT-ID TLV use is now elevated to SHOULD when
is enabled in the underlying IGP. it is enabled in the underlying IGP.
11. Clarified that IPv6 Link-Local Addresses are not advertised in 11. Clarified that IPv6 link-local addresses are not advertised in
the Link Descriptor TLVs and the local/remote identifiers are to the Link Descriptor TLVs and the local/remote identifiers are to
be used instead for links with IPv6 link-local addresses only. be used instead for links with IPv6 link-local addresses only.
12. Update the usage of OSPF Route Type TLV to mandate its use for 12. Updated the usage of OSPF Route Type TLV to mandate its use for
OSPF prefixes in Section 5.2.3.1 since this is required for OSPF prefixes in Section 5.2.3.1 since this is required for
segregation of intra-area prefixes that are used to reach a node segregation of intra-area prefixes that are used to reach a node
(e.g. a loopback) from other types of inter-area and external (e.g., a loopback) from other types of inter-area and external
prefixes. prefixes.
13. Clarification of the specific OSPFv2 and OSPFv3 protocol TLV 13. Clarified the specific OSPFv2 and OSPFv3 protocol TLV space to
space to be used in the node, link, and prefix opaque attribute be used in the Node, Link, and Prefix Opaque Attribute TLVs.
TLVs.
14. Clarification on the length of the Node Flag Bits and IGP Flags 14. Clarified that the length of the Node Flag Bits and IGP Flags
TLVs to be one octet. TLVs are to be one octet.
15. Updated the Node Name TLV in Section 5.3.1.3 with the OSPF 15. Updated the Node Name TLV in Section 5.3.1.3 with the OSPF
specification. specification.
16. Clarification on the size of the IS-IS Narrow Metric 16. Clarified the size of the IS-IS Narrow Metric advertisement via
advertisement via the IGP Metric TLV and the handling of the the IGP Metric TLV and the handling of the unused bits.
unused bits.
17. Clarified the advertisement of the prefix corresponding to the 17. Clarified the advertisement of the prefix corresponding to the
LAN segment in an OSPF network in Section 5.11. LAN segment in an OSPF network in Section 5.11.
18. Clarified the advertisement and support for OSPF specific 18. Clarified the advertisement and support for OSPF-specific
concepts like Virtual links, Sham links, and Type 4 LSAs in concepts like virtual links, sham links, and Type 4 LSAs in
Section 5.7 and Section 5.8. Sections 5.7 and 5.8.
19. Introduced Private Use TLV code point space and specified their 19. Introduced the Private Use TLV code point space and specified
encoding in Section 5.4. their encoding in Section 5.4.
20. Introduced Section 5.9 where issues related to the consistency 20. In Section 5.9, introduced where issues related to the
of reporting IGP link-state along with their solutions are consistency of reporting IGP link-state along with their
covered. solutions are covered.
21. Added recommendation for isolation of BGP-LS sessions from other 21. Added a recommendation for isolation of BGP-LS sessions from
BGP route exchange to avoid errors and faults in BGP-LS other BGP route exchanges to avoid errors and faults in BGP-LS
affecting the normal BGP routing. affecting the normal BGP routing.
22. Updated the Fault Management section with detailed rules based 22. Updated the Fault Management section with detailed rules based
on the role of the BGP Speaker in the BGP-LS information on the role of the BGP Speaker in the BGP-LS information
propagation flow. propagation flow.
23. Change to the management of BGP-LS IANA registries from 23. Changed the management of BGP-LS IANA registries from
"Specification Required" to "Expert Review" along with updated "Specification Required" to "Expert Review" along with updated
guidelines for Designated Experts. More specifically the guidelines for designated experts, more specifically, the
inclusion of changes introduced via [RFC9029] that is obsoleted inclusion of changes introduced via [RFC9029] that are obsoleted
by this document. by this document.
24. Added BGP-LS IANA registries with "Expert Review" policy for the 24. Added BGP-LS IANA registries with "Expert Review" policy for the
flag fields of various TLVs that was missed out. Renamed the flag fields of various TLVs that was missed out. Renamed the
BGP-LS TLV registry and removed the "IS-IS TLV/Sub-TLV" column BGP-LS TLV registry and removed the "IS-IS TLV/Sub-TLV" column
from it. from it.
Acknowledgements
This document update to the BGP-LS specification [RFC7752] is a
result of feedback and input from the discussions in the IDR Working
Group. It also incorporates certain details and clarifications based
on implementation and deployment experience with BGP-LS.
Cengiz Alaettinoglu and Parag Amritkar brought forward the need to
clarify the advertisement of a LAN subnet for OSPF.
We would like to thank Balaji Rajagopalan, Srihari Sangli, Shraddha
Hegde, Andrew Stone, Jeff Tantsura, Acee Lindem, Les Ginsberg, Jie
Dong, Aijun Wang, Nandan Saha, Joel Halpern, and Gyan Mishra for
their review and feedback on this document. Thanks to Tom Petch for
his review and comments on the IANA Considerations section. We would
also like to thank Jeffrey Haas for his detailed shepherd review and
input for improving the document.
The detailed AD review by Alvaro Retana and his suggestions have
helped improve this document significantly.
We would like to thank Robert Varga for his significant contribution
to [RFC7752].
We would like to thank Nischal Sheth, Alia Atlas, David Ward, Derek
Yeung, Murtuza Lightwala, John Scudder, Kaliraj Vairavakkalai, Les
Ginsberg, Liem Nguyen, Manish Bhardwaj, Matt Miller, Mike Shand,
Peter Psenak, Rex Fernando, Richard Woundy, Steven Luong, Tamas
Mondal, Waqas Alam, Vipin Kumar, Naiming Shen, Carlos Pignataro,
Balaji Rajagopalan, Yakov Rekhter, Alvaro Retana, Barry Leiba, and
Ben Campbell for their comments on [RFC7752].
Contributors
The following persons contributed significant text to [RFC7752] and
this document. They should be considered coauthors.
Hannes Gredler
Rtbrick
Email: hannes@rtbrick.com
Jan Medved
Cisco Systems Inc.
United States of America
Email: jmedved@cisco.com
Stefano Previdi
Huawei Technologies
Italy
Email: stefano@previdi.net
Adrian Farrel
Old Dog Consulting
Email: adrian@olddog.co.uk
Saikat Ray
Individual
United States of America
Email: raysaikat@gmail.com
Author's Address Author's Address
Ketan Talaulikar (editor) Ketan Talaulikar (editor)
Cisco Systems Cisco Systems
India India
Email: ketant.ietf@gmail.com Email: ketant.ietf@gmail.com
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