rfc9346.original   rfc9346.txt 
Internet Engineering Task Force M. Chen Internet Engineering Task Force (IETF) M. Chen
Internet-Draft Huawei Request for Comments: 9346 Huawei
Obsoletes: 5316 (if approved) L. Ginsberg Obsoletes: 5316 L. Ginsberg
Intended status: Standards Track Cisco Systems Category: Standards Track Cisco Systems
Expires: 1 April 2023 S. Previdi ISSN: 2070-1721 S. Previdi
Huawei Technologies Huawei Technologies
D. Xiaodong X. Duan
China Mobile China Mobile
28 September 2022 January 2023
IS-IS Extensions in Support of Inter-Autonomous System (AS) MPLS and IS-IS Extensions in Support of Inter-Autonomous System (AS) MPLS and
GMPLS Traffic Engineering GMPLS Traffic Engineering
draft-ietf-lsr-isis-rfc5316bis-07
Abstract Abstract
This document describes extensions to the Intermediate System to This document describes extensions to the Intermediate System to
Intermediate System (IS-IS) protocol to support Multiprotocol Label Intermediate System (IS-IS) protocol to support Multiprotocol Label
Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering
(TE) for multiple Autonomous Systems (ASs). It defines IS-IS (TE) for multiple Autonomous Systems (ASes). It defines IS-IS
extensions for the flooding of TE information about inter-AS links, extensions for the flooding of TE information about inter-AS links,
which can be used to perform inter-AS TE path computation. which can be used to perform inter-AS TE path computation.
No support for flooding information from within one AS to another AS No support for flooding information from within one AS to another AS
is proposed or defined in this document. is proposed or defined in this document.
This document builds on RFC 5316 by adding support for IPv6-only This document builds on RFC 5316 by adding support for IPv6-only
operation. operation.
This document obsoletes RFC 5316. This document obsoletes RFC 5316.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 1 April 2023. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9346.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language
2.1. A Note on Non-Objectives . . . . . . . . . . . . . . . . 4 2. Problem Statement
2.2. Per-Domain Path Determination . . . . . . . . . . . . . . 5 2.1. A Note on Non-objectives
2.3. Backward Recursive Path Computation . . . . . . . . . . . 6 2.2. Per-Domain Path Determination
3. Extensions to ISIS-TE . . . . . . . . . . . . . . . . . . . . 7 2.3. Backward-Recursive Path Computation
3.1. Choosing the TE Router ID Value . . . . . . . . . . . . . 8 3. Extensions to IS-IS TE
3.2. Inter-AS Reachability TLV . . . . . . . . . . . . . . . . 9 3.1. Choosing the TE Router ID Value
3.3. TE Router ID . . . . . . . . . . . . . . . . . . . . . . 10 3.2. Inter-AS Reachability Information TLV
3.4. Sub-TLVs for Inter-AS Reachability TLV . . . . . . . . . 11 3.3. TE Router ID
3.4.1. Remote AS Number Sub-TLV . . . . . . . . . . . . . . 11 3.4. Sub-TLVs for Inter-AS Reachability Information TLV
3.4.2. IPv4 Remote ASBR ID Sub-TLV . . . . . . . . . . . . . 12 3.4.1. Remote AS Number Sub-TLV
3.4.3. IPv6 Remote ASBR ID Sub-TLV . . . . . . . . . . . . . 12 3.4.2. IPv4 Remote ASBR Identifier Sub-TLV
3.4.4. IPv6 Local ASBR ID sub-TLV . . . . . . . . . . . . . 13 3.4.3. IPv6 Remote ASBR Identifier Sub-TLV
3.5. Sub-TLVs for IS-IS Router Capability TLV . . . . . . . . 14 3.4.4. IPv6 Local ASBR Identifier Sub-TLV
3.5.1. IPv4 TE Router ID sub-TLV . . . . . . . . . . . . . . 14 3.5. Sub-TLVs for IS-IS Router CAPABILITY TLV
3.5.2. IPv6 TE Router ID sub-TLV . . . . . . . . . . . . . . 14 3.5.1. IPv4 TE Router ID Sub-TLV
4. Procedure for Inter-AS TE Links . . . . . . . . . . . . . . . 15 3.5.2. IPv6 TE Router ID Sub-TLV
4.1. Origin of Proxied TE Information . . . . . . . . . . . . 16 4. Procedure for Inter-AS TE Links
5. Security Considerations . . . . . . . . . . . . . . . . . . . 16 4.1. Origin of Proxied TE Information
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 5. Security Considerations
6.1. Inter-AS Reachability TLV . . . . . . . . . . . . . . . . 17 6. IANA Considerations
6.2. Sub-TLVs for the Inter-AS Reachability TLV . . . . . . . 18 6.1. Inter-AS Reachability Information TLV
6.3. Sub-TLVs for the IS-IS Router Capability TLV . . . . . . 18 6.2. Sub-TLVs for the Inter-AS Reachability Information TLV
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 6.3. Sub-TLVs for the IS-IS Router CAPABILITY TLV
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 7. References
8.1. Normative References . . . . . . . . . . . . . . . . . . 18 7.1. Normative References
8.2. Informative References . . . . . . . . . . . . . . . . . 19 7.2. Informative References
Appendix A. Changes to RFC 5316 . . . . . . . . . . . . . . . . 20 Appendix A. Changes to RFC 5316
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 Acknowledgements
Authors' Addresses
1. Introduction 1. Introduction
[RFC5305] defines extensions to the IS-IS protocol [RFC1195] to [RFC5305] defines extensions to the IS-IS protocol [RFC1195] to
support intra-area Traffic Engineering (TE). The extensions provide support intra-area Traffic Engineering (TE). The extensions provide
a way of encoding the TE information for TE-enabled links within the a way of encoding the TE information for TE-enabled links within the
network (TE links) and flooding this information within an area. The network (TE links) and flooding this information within an area. The
extended IS reachability TLV and traffic engineering router ID TLV, extended IS reachability TLV and Traffic Engineering router ID TLV,
which are defined in [RFC5305], are used to carry such TE which are defined in [RFC5305], are used to carry such TE
information. The extended IS reachability TLV has several nested information. The extended IS reachability TLV has several nested
sub-TLVs that describe the TE attributes for a TE link. sub-TLVs that describe the TE attributes for a TE link.
[RFC6119] and [RFC5307] define similar extensions to IS-IS in support [RFC6119] and [RFC5307] define similar extensions to IS-IS in support
of IPv6 and Generalized Multiprotocol Label Switching (GMPLS) TE of IPv6 and GMPLS TE, respectively.
respectively.
Requirements for establishing Multiprotocol Label Switching (MPLS) TE Requirements for establishing Multiprotocol Label Switching (MPLS) TE
Label Switched Paths (LSPs) that cross multiple Autonomous Systems Label Switched Paths (LSPs) that cross multiple Autonomous Systems
(ASes) are described in [RFC4216]. As described in [RFC4216], a (ASes) are described in [RFC4216]. As described in [RFC4216], a
method SHOULD provide the ability to compute a path spanning multiple method SHOULD provide the ability to compute a path spanning multiple
ASes. So a path computation entity that may be the head-end Label ASes. So a path computation entity that may be the head-end Label
Switching Router (LSR), an AS Border Router (ASBR), or a Path Switching Router (LSR), an AS Border Router (ASBR), or a Path
Computation Element (PCE) [RFC4655] needs to know the TE information Computation Element (PCE) [RFC4655] needs to know the TE information
not only of the links within an AS, but also of the links that not only of the links within an AS but also of the links that connect
connect to other ASes. to other ASes.
In this document, a new TLV, which is referred to as the inter-AS In this document, the Inter-AS Reachability Information TLV is
reachability TLV, is defined to advertise inter-AS TE information, defined to advertise inter-AS TE information, and four sub-TLVs are
and three new sub-TLVs are defined for inclusion in the inter-AS defined for inclusion in the Inter-AS Reachability Information TLV to
reachability TLV to carry the information about the remote AS number carry the information about the Remote AS Number, Remote ASBR
and remote ASBR ID. The sub-TLVs defined in [RFC5305][RFC6119] and Identifier, and IPv6 Local ASBR Identifier. The sub-TLVs defined in
other documents for inclusion in the extended IS reachability TLV for [RFC5305], [RFC6119], and other documents for inclusion in the
describing the TE properties of a TE link are applicable to be extended IS reachability TLV for describing the TE properties of a TE
included in the Inter-AS Reachability TLV for describing the TE link are applicable to be included in the Inter-AS Reachability
properties of an inter-AS TE link as well. Also, two more new sub- Information TLV for describing the TE properties of an inter-AS TE
TLVs are defined for inclusion in the IS-IS router capability TLV to link as well. Also, two more sub-TLVs are defined for inclusion in
carry the TE Router ID when the TE Router ID is needed to reach all the IS-IS Router CAPABILITY TLV to carry the TE Router ID when the TE
routers within an entire IS-IS routing domain. The extensions are Router ID is needed to reach all routers within an entire IS-IS
equally applicable to IPv4 and IPv6 as identical extensions to routing domain. The extensions are equally applicable to IPv4 and
[RFC5305] and [RFC6119]. Detailed definitions and procedures are IPv6 as identical extensions to [RFC5305] and [RFC6119]. Detailed
discussed in the following sections. definitions and procedures are discussed in the following sections.
This document does not propose or define any mechanisms to advertise This document does not propose or define any mechanisms to advertise
any other extra-AS TE information within IS-IS. See Section 2.1 for any other extra-AS TE information within IS-IS. See Section 2.1 for
a full list of non-objectives for this work. a full list of non-objectives for this work.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Problem Statement 2. Problem Statement
As described in [RFC4216], in the case of establishing an inter-AS TE As described in [RFC4216], in the case of establishing an inter-AS TE
LSP that traverses multiple ASes, the Path message [RFC3209] may LSP that traverses multiple ASes, the Path message [RFC3209] may
include the following elements in the Explicit Route Object (ERO) in include the following elements in the Explicit Route Object (ERO) in
order to describe the path of the LSP: order to describe the path of the LSP:
* a set of AS numbers as loose hops; and/or * a set of AS numbers as loose hops and/or
* a set of LSRs including ASBRs as loose hops. * a set of LSRs including ASBRs as loose hops.
Two methods for determining inter-AS paths have been described Two methods for determining inter-AS paths have been described
elsewhere. The per-domain method [RFC5152] determines the path one elsewhere. The per-domain method [RFC5152] determines the path one
domain at a time. The backward recursive method [RFC5441] uses domain at a time. The backward-recursive method [RFC5441] uses
cooperation between PCEs to determine an optimum inter-domain path. cooperation between PCEs to determine an optimum inter-domain path.
The sections that follow examine how inter-AS TE link information The sections that follow examine how inter-AS TE link information
could be useful in both cases. could be useful in both cases.
2.1. A Note on Non-Objectives 2.1. A Note on Non-objectives
It is important to note that this document does not make any change It is important to note that this document does not make any change
to the confidentiality and scaling assumptions surrounding the use of to the confidentiality and scaling assumptions surrounding the use of
ASes in the Internet. In particular, this document is conformant to ASes in the Internet. In particular, this document is conformant to
the requirements set out in [RFC4216]. the requirements set out in [RFC4216].
The following features are explicitly excluded: The following features are explicitly excluded:
* There is no attempt to distribute TE information from within one * There is no attempt to distribute TE information from within one
AS to another AS. AS to another AS.
skipping to change at page 5, line 24 skipping to change at line 207
for an example. for an example.
R1------R3----R5-----R7------R9-----R11 R1------R3----R5-----R7------R9-----R11
| | \ | / | | | \ | / |
| | \ | ---- | | | \ | ---- |
| | \ | / | | | \ | / |
R2------R4----R6 --R8------R10----R12 R2------R4----R6 --R8------R10----R12
: : : :
<-- AS1 -->:<---- AS2 --->:<--- AS3 ---> <-- AS1 -->:<---- AS2 --->:<--- AS3 --->
Figure 1: Inter-AS Reference Model Figure 1: Inter-AS Reference Model
The figure shows three ASes (AS1, AS2, and AS3) and twelve LSRs (R1 The figure shows three ASes (AS1, AS2, and AS3) and twelve LSRs (R1
through R12). R3 and R4 are ASBRs in AS1. R5, R6, R7, and R8 are through R12). R3 and R4 are ASBRs in AS1. R5, R6, R7, and R8 are
ASBRs in AS2. R9 and R10 are ASBRs in AS3. ASBRs in AS2. R9 and R10 are ASBRs in AS3.
If an inter-AS TE LSP is planned to be established from R1 to R12, If an inter-AS TE LSP is planned to be established from R1 to R12,
the AS sequence will be: AS1, AS2, AS3. the AS sequence will be: AS1, AS2, AS3.
Suppose that the Path message enters AS2 from R3. The next hop in Suppose that the Path message enters AS2 from R3. The next hop in
the ERO shows AS3, and R5 must determine a path segment across AS2 to the ERO shows AS3, and R5 must determine a path segment across AS2 to
reach AS3. It has a choice of three exit points from AS2 (R6, R7, reach AS3. It has a choice of three exit points from AS2 (R6, R7,
and R8), and it needs to know which of these provide TE connectivity and R8), and it needs to know which of these provide TE connectivity
to AS3, and whether the TE connectivity (for example, available to AS3 and whether the TE connectivity (for example, available
bandwidth) is adequate for the requested LSP. bandwidth) is adequate for the requested LSP.
Alternatively, if the next hop in the ERO is an entry ASBR for AS3 Alternatively, if the next hop in the ERO is an entry ASBR for AS3
(say R9), R5 needs to know which of its exit ASBRs has a TE link that (say R9), R5 needs to know which of its exit ASBRs has a TE link that
connects to R9. Since there may be multiple ASBRs that are connected connects to R9. Since there may be multiple ASBRs that are connected
to R9 (both R7 and R8 in this example), R5 also needs to know the TE to R9 (both R7 and R8 in this example), R5 also needs to know the TE
properties of the inter-AS TE links so that it can select the correct properties of the inter-AS TE links so that it can select the correct
exit ASBR. exit ASBR.
Once the Path message reaches the exit ASBR, any choice of inter-AS Once the Path message reaches the exit ASBR, any choice of inter-AS
skipping to change at page 6, line 25 skipping to change at line 257
* Identity (TE Router ID) of the neighboring ASBR connected to by * Identity (TE Router ID) of the neighboring ASBR connected to by
each inter-AS TE link. each inter-AS TE link.
In GMPLS networks, further information may also be required to select In GMPLS networks, further information may also be required to select
the correct TE links as defined in [RFC5307]. the correct TE links as defined in [RFC5307].
The example above shows how this information is needed at the entry- The example above shows how this information is needed at the entry-
point ASBRs for each AS (or the PCEs that provide computation point ASBRs for each AS (or the PCEs that provide computation
services for the ASBRs). However, this information is also needed services for the ASBRs). However, this information is also needed
throughout the local AS if path computation functionality is fully throughout the local AS if path computation functionality is fully
distributed among LSRs in the local AS, for example to support LSPs distributed among LSRs in the local AS, for example, to support LSPs
that have start points (ingress nodes) within the AS. that have start points (ingress nodes) within the AS.
2.3. Backward Recursive Path Computation 2.3. Backward-Recursive Path Computation
Another scenario using PCE techniques has the same problem. Another scenario using PCE techniques has the same problem.
[RFC5441] defines a PCE-based TE LSP computation method (called [RFC5441] defines a PCE-based TE LSP computation method (called
Backward Recursive Path Computation) to compute optimal inter-domain "Backward-Recursive Path Computation (BRPC)") to compute optimal
constrained MPLS-TE or GMPLS LSPs. In this path computation method, inter-domain constrained MPLS-TE or GMPLS LSPs. In this path
a specific set of traversed domains (ASes) are assumed to be selected computation method, a specific set of traversed domains (ASes) are
before computation starts. Each downstream PCE in domain(i) returns assumed to be selected before computation starts. Each downstream
to its upstream neighbor PCE in domain(i-1) a multipoint-to-point PCE in domain(i) returns to its upstream neighbor PCE in domain(i-1)
tree of potential paths. Each tree consists of the set of paths from a multipoint-to-point tree of potential paths. Each tree consists of
all boundary nodes located in domain(i) to the destination where each the set of paths from all boundary nodes located in domain(i) to the
path satisfies the set of required constraints for the TE LSP destination where each path satisfies the set of required constraints
(bandwidth, affinities, etc.). for the TE LSP (bandwidth, affinities, etc.).
So a PCE needs to select boundary nodes (that is, ASBRs) that provide So a PCE needs to select boundary nodes (that is, ASBRs) that provide
connectivity from the upstream AS. In order for the tree of paths connectivity from the upstream AS. In order for the tree of paths
provided by one PCE to its neighbor to be correlated, the identities provided by one PCE to its neighbor to be correlated, the identities
of the ASBRs for each path need to be referenced. Thus, the PCE must of the ASBRs for each path need to be referenced. Thus, the PCE must
know the identities of the ASBRs in the remote AS that are reached by know the identities of the ASBRs in the remote AS that are reached by
any inter-AS TE link, and, in order to provide only suitable paths in any inter-AS TE link, and, in order to provide only suitable paths in
the tree, the PCE must know the TE properties of the inter-AS TE the tree, the PCE must know the TE properties of the inter-AS TE
links. See the following figure as an example. links. See the following figure as an example.
skipping to change at page 7, line 16 skipping to change at line 294
/ : : / : :
/ : : / : :
R1------R3----R5-----R7------R9-----R11 R1------R3----R5-----R7------R9-----R11
| | \ | / | | | \ | / |
| | \ | ---- | | | \ | ---- |
| | \ | / | | | \ | / |
R2------R4----R6 --R8------R10----R12 R2------R4----R6 --R8------R10----R12
: : : :
<-- AS1 -->:<---- AS2 --->:<--- AS3 ---> <-- AS1 -->:<---- AS2 --->:<--- AS3 --->
Figure 2: BRPC for Inter-AS Reference Model Figure 2: BRPC for Inter-AS Reference Model
The figure shows three ASes (AS1, AS2, and AS3), three PCEs (PCE1, The figure shows three ASes (AS1, AS2, and AS3), three PCEs (PCE1,
PCE2, and PCE3), and twelve LSRs (R1 through R12). R3 and R4 are PCE2, and PCE3), and twelve LSRs (R1 through R12). R3 and R4 are
ASBRs in AS1. R5, R6, R7, and R8 are ASBRs in AS2. R9 and R10 are ASBRs in AS1. R5, R6, R7, and R8 are ASBRs in AS2. R9 and R10 are
ASBRs in AS3. PCE1, PCE2, and PCE3 cooperate to perform inter-AS ASBRs in AS3. PCE1, PCE2, and PCE3 cooperate to perform inter-AS
path computation and are responsible for path segment computation path computation and are responsible for path segment computation
within their own domain(s). within their own domain(s).
If an inter-AS TE LSP is planned to be established from R1 to R12, If an inter-AS TE LSP is planned to be established from R1 to R12,
the traversed domains are assumed to be selected: AS1->AS2->AS3, and the traversed domains are assumed to be selected (AS1->AS2->AS3), and
the PCE chain is: PCE1->PCE2->PCE3. First, the path computation the PCE chain is PCE1->PCE2->PCE3. First, the path computation
request originated from the PCC (R1) is relayed by PCE1 and PCE2 request originated from the Path Computation Client (PCC) (R1) is
along the PCE chain to PCE3. Then, PCE3 begins to compute the path relayed by PCE1 and PCE2 along the PCE chain to PCE3. Then, PCE3
segments from the entry boundary nodes that provide connection from begins to compute the path segments from the entry boundary nodes
AS2 to the destination (R12). But, to provide suitable path that provide connection from AS2 to the destination (R12). But, to
segments, PCE3 must determine which entry boundary nodes provide provide suitable path segments, PCE3 must determine which entry
connectivity to its upstream neighbor AS (identified by its AS boundary nodes provide connectivity to its upstream neighbor AS
number), and must know the TE properties of the inter-AS TE links. (identified by its AS number) and must know the TE properties of the
In the same way, PCE2 also needs to determine the entry boundary inter-AS TE links. In the same way, PCE2 also needs to determine the
nodes according to its upstream neighbor AS and the inter-AS TE link entry boundary nodes according to its upstream neighbor AS and the
capabilities. inter-AS TE link capabilities.
Thus, to support Backward Recursive Path Computation, the same Thus, to support BRPC, the same information listed in Section 2.2 is
information listed in Section 2.2 is required. The AS number of the required. The AS number of the neighboring AS connected to by each
neighboring AS connected to by each inter-AS TE link is particularly inter-AS TE link is particularly important.
important.
3. Extensions to ISIS-TE 3. Extensions to IS-IS TE
Note that this document does not define mechanisms for distribution Note that this document does not define mechanisms for distribution
of TE information from one AS to another, does not distribute any of TE information from one AS to another, does not distribute any
form of TE reachability information for destinations outside the AS, form of TE reachability information for destinations outside the AS,
does not change the PCE architecture or usage, does not suggest or does not change the PCE architecture or usage, does not suggest or
recommend any form of TE aggregation, and does not feed private recommend any form of TE aggregation, and does not feed private
information between ASes. See Section 2.1. information between ASes. See Section 2.1.
In this document, for the advertisement of inter-AS TE links, a new In this document, the Inter-AS Reachability Information TLV is
TLV, which is referred to as the inter-AS reachability TLV, is defined for the advertisement of inter-AS TE links. Four sub-TLVs
defined. Three new sub-TLVs are also defined for inclusion in the are also defined for inclusion in the Inter-AS Reachability
inter-AS reachability TLV to carry the information about the Information TLV to carry the information about the neighboring AS
neighboring AS number and the remote ASBR ID of an inter-AS link. number, the Remote ASBR Identifier, and IPv6 Local ASBR Identifier of
The sub-TLVs defined in [RFC5305], [RFC6119], and other documents for an inter-AS link. The sub-TLVs defined in [RFC5305], [RFC6119], and
inclusion in the extended IS reachability TLV are applicable to be other documents for inclusion in the extended IS reachability TLV are
included in the inter-AS reachability TLV for inter-AS TE links applicable to be included in the Inter-AS Reachability Information
advertisement. TLV for the advertisement of inter-AS TE links.
This document also defines two new sub-TLVs for inclusion in the IS- This document also defines two sub-TLVs for inclusion in the IS-IS
IS router capability TLV to carry the TE Router ID when the TE Router Router CAPABILITY TLV to carry the TE Router ID when the TE Router ID
ID is needed to reach all routers within an entire IS-IS routing is needed to reach all routers within an entire IS-IS routing domain.
domain.
While some of the TE information of an inter-AS TE link may be While some of the TE information of an inter-AS TE link may be
available within the AS from other protocols, in order to avoid any available within the AS from other protocols, in order to avoid any
dependency on where such protocols are processed, this mechanism dependency on where such protocols are processed, this mechanism
carries all the information needed for the required TE operations. carries all the information needed for the required TE operations.
3.1. Choosing the TE Router ID Value 3.1. Choosing the TE Router ID Value
Subsequent sections specify advertisement of a TE Router ID value for Subsequent sections specify advertisement of a TE Router ID value for
IPv4 and/or IPv6. This section defines how this value is chosen. IPv4 and/or IPv6. This section defines how this value is chosen.
A TE Router ID MUST be an address which is unique within the IS-IS A TE Router ID MUST be an address that is unique within the IS-IS
domain and stable i.e., it can always be referenced in a path that domain and stable, i.e., it can always be referenced in a path that
will be reachable from multiple hops away, regardless of the state of will be reachable from multiple hops away, regardless of the state of
the node's interfaces. the node's interfaces.
When advertising an IPv4 address as a TE Router ID, if the Traffic When advertising an IPv4 address as a TE Router ID, if the Traffic
Engineering Router ID TLV [RFC5305] is being advertised, then the Engineering router ID TLV [RFC5305] is being advertised, then the
address SHOULD be identical to the address in the Traffic Engineering address SHOULD be identical to the address in the Traffic Engineering
Router ID TLV. The TE Router ID MAY be identical to an IP Interface router ID TLV. The TE Router ID MAY be identical to an IP Interface
Address [RFC1195] advertised by the originating IS so long as the Address [RFC1195] advertised by the originating IS so long as the
address meets the requirements specified above. address meets the requirements specified above.
When advertising an IPv6 address as a TE Router ID, if the IPv6 TE When advertising an IPv6 address as a TE Router ID, if the IPv6 TE
Router ID TLV [RFC6119] is being advertised, then the address SHOULD Router ID TLV [RFC6119] is being advertised, then the address SHOULD
be identical to the address in the IPv6 TE Router ID TLV. The TE be identical to the address in the IPv6 TE Router ID TLV. The TE
Router ID MAY be identical to a non-link-local IPv6 Interface Address Router ID MAY be identical to a non-link-local IPv6 Interface Address
advertised by the originating IS in a Link State PDU using the IPv6 advertised by the originating IS in a Link State PDU using the IPv6
Intf. Addr TLV [RFC5308] so long as the address meets the Interface Address TLV [RFC5308] so long as the address meets the
requirements specified above. requirements specified above.
3.2. Inter-AS Reachability TLV 3.2. Inter-AS Reachability Information TLV
The inter-AS reachability TLV has type 141 (see Section 6.1) and The Inter-AS Reachability Information TLV has type 141 (see
contains a data structure consisting of: Section 6.1) and contains a data structure consisting of:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router ID (4 octets) | | Router ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| default metric | (3 octets) | Default Metric | (3 octets)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | (1 octet) | Flags | (1 octet)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|sub-TLVs length| (1 octet) |Sub-TLVs Length| (1 octet)
+-+-+-+-+-+-+-+-+-+-+-+- +-+-+-+-+-+-+-+-+-+-+-+-
| sub-TLVs ... (0-246 octets) | Sub-TLVs ... (0-246 octets)
+-+-+-+-+-+-+-+-+-+-+-+- +-+-+-+-+-+-+-+-+-+-+-+-
Flags consists of the following: Flags consists of the following:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ 0 1 2 3 4 5 6 7
|S|D| Rsvd | +-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+ |S|D| Rsvd |
+-+-+-+-+-+-+-+-+
where: where:
S bit: If the S bit is set(1), the Inter-AS Reachability TLV S bit: If the S bit is set(1), the Inter-AS Reachability Information
MUST be flooded across the entire routing domain. If the S bit is TLV MUST be flooded across the entire routing domain. If the S
not set(0), the TLV MUST NOT be leaked between levels. This bit MUST bit is not set(0), the TLV MUST NOT be leaked between levels.
NOT be altered during the TLV leaking. This bit MUST NOT be altered during the TLV leaking.
D bit: When the Inter-AS Reachability TLV is leaked from D bit: When the Inter-AS Reachability Information TLV is leaked from
Level 2 (L2) to Level 1 (L1), the D bit MUST be set. Otherwise, this Level 2 (L2) to Level 1 (L1), the D bit MUST be set. Otherwise,
bit MUST be clear. Inter-AS Reachability TLVs with the D bit set this bit MUST be clear. Inter-AS Reachability Information TLVs
MUST NOT be leaked from Level 1 to Level 2. This is to prevent TLV with the D bit set MUST NOT be leaked from Level 1 to Level 2.
looping. This is to prevent TLV looping.
Reserved(Rsvd) bits MUST be zero when originated and ignored Reserved (Rsvd): Reserved bits MUST be zero when originated and
when received. ignored when received.
Compared to the extended reachability TLV which is defined in Compared to the extended IS reachability TLV, which is defined in
[RFC5305], the inter-AS reachability TLV replaces the "7 octets of [RFC5305], the Inter-AS Reachability Information TLV replaces the "7
System ID and Pseudonode Number" field with a "4 octets of Router ID" octets of System ID and Pseudonode Number" field with a "4 octets of
field and introduces an extra "control information" field, which Router ID" field and introduces an extra "control information" field,
consists of a flooding-scope bit (S bit), an up/down bit (D bit), and which consists of a flooding-scope bit (S bit), an up/down bit (D
6 reserved bits. bit), and 6 reserved bits.
The Router ID field of the inter-AS reachability TLV is 4 octets in The Router ID field of the Inter-AS Reachability Information TLV is 4
length and has a value as defined in Section 3.1. If the originating octets in length and has a value as defined in Section 3.1. If the
node does not support IPv4, then the reserved value 0.0.0.0 MUST be originating node does not support IPv4, then the reserved value
used in the Router ID field and the IPv6 Router ID sub-TLV MUST be 0.0.0.0 MUST be used in the Router ID field, and the IPv6 Router ID
present in the inter-AS reachability TLV. The Router ID could be sub-TLV MUST be present in the Inter-AS Reachability Information TLV.
used to indicate the source of the inter-AS reachability TLV. The Router ID could be used to indicate the source of the Inter-AS
Reachability Information TLV.
The flooding procedures for inter-AS reachability TLV are identical The flooding procedures for the Inter-AS Reachability Information TLV
to the flooding procedures for the GENINFO TLV, which are defined in are identical to the flooding procedures for the GENINFO TLV, which
Section 4 of [RFC6823]. These procedures have been previously are defined in Section 4 of [RFC6823]. These procedures have been
discussed in [RFC7981]. The flooding-scope bit (S bit) SHOULD be set previously discussed in [RFC7981]. The flooding-scope bit (S bit)
to 0 if the flooding scope is to be limited to within the single IGP SHOULD be set to 0 if the flooding scope is to be limited to within
area to which the ASBR belongs. It MAY be set to 1 if the the single IGP area to which the ASBR belongs. It MAY be set to 1 if
information is intended to reach all routers (including area border the information is intended to reach all routers (including area
routers, ASBRs, and PCEs) in the entire IS-IS routing domain. The border routers, ASBRs, and PCEs) in the entire IS-IS routing domain.
choice between the use of 0 or 1 is an AS-wide policy choice, and The choice between the use of 0 or 1 is an AS-wide policy choice, and
configuration control SHOULD be provided in ASBR implementations that configuration control SHOULD be provided in ASBR implementations that
support the advertisement of inter-AS TE links. support the advertisement of inter-AS TE links.
The sub-TLVs defined in [RFC5305], [RFC6119], and other documents for The sub-TLVs defined in [RFC5305], [RFC6119], and other documents for
describing the TE properties of a TE link are also applicable to the describing the TE properties of a TE link are also applicable to the
inter-AS reachability TLV for describing the TE properties of an Inter-AS Reachability Information TLV for describing the TE
Inter-AS TE link. Apart from these sub-TLVs, four new sub-TLVs are properties of an inter-AS TE link. Apart from these sub-TLVs, four
defined for inclusion in the inter-AS reachability TLV defined in sub-TLVs are defined for inclusion in the Inter-AS Reachability
this document: Information TLV defined in this document:
Sub-TLV type Length Name +==============+========+=============================+
------------ ------ --------------------------- | Sub-TLV type | Length | Name |
24 4 remote AS number +==============+========+=============================+
25 4 IPv4 remote ASBR identifier | 24 | 4 | Remote AS Number |
26 16 IPv6 remote ASBR identifier +--------------+--------+-----------------------------+
TBD1 16 IPv6 local ASBR identifier | 25 | 4 | IPv4 Remote ASBR Identifier |
+--------------+--------+-----------------------------+
| 26 | 16 | IPv6 Remote ASBR Identifier |
+--------------+--------+-----------------------------+
| 45 | 16 | IPv6 Local ASBR Identifier |
+--------------+--------+-----------------------------+
Detailed definitions of the four new sub-TLVs are described in Table 1
Sections 3.3.1, 3.3.2, 3.3.3, and 3.3.4.
Detailed definitions of these four sub-TLVs are described in Sections
3.4.1, 3.4.2, 3.4.3, and 3.4.4.
3.3. TE Router ID 3.3. TE Router ID
The Traffic Engineering router ID TLV and IPv6 TE Router ID TLV, The Traffic Engineering router ID TLV and IPv6 TE Router ID TLV,
which are defined in [RFC5305] and [RFC6119] respectively, only have which are defined in [RFC5305] and [RFC6119], respectively, only have
area flooding-scope. When performing inter-AS TE, the TE Router ID area flooding scope. When performing inter-AS TE, the TE Router ID
MAY be needed to reach all routers within an entire IS-IS routing MAY be needed to reach all routers within an entire IS-IS routing
domain and it MUST have the same flooding scope as the Inter-AS domain, and it MUST have the same flooding scope as the Inter-AS
Reachability TLV does. Reachability Information TLV does.
[RFC7981] defines a generic advertisement mechanism for IS-IS which [RFC7981] defines a generic advertisement mechanism for IS-IS, which
allows a router to advertise its capabilities within an IS-IS area or allows a router to advertise its capabilities within an IS-IS area or
an entire IS-IS routing domain. [RFC7981] also points out that the an entire IS-IS routing domain. [RFC7981] also points out that the
TE Router ID is a candidate to be carried in the IS-IS router TE Router ID is a candidate to be carried in the IS-IS Router
capability TLV when performing inter-area TE. CAPABILITY TLV when performing inter-area TE.
This document uses such mechanism for TE Router ID advertisement when This document uses such mechanism for TE Router ID advertisement when
the TE Router ID is needed to reach all routers within an entire IS- the TE Router ID is needed to reach all routers within an entire IS-
IS Routing domain. Two new sub-TLVs are defined for inclusion in the IS routing domain. Two sub-TLVs are defined for inclusion in the IS-
IS-IS Router Capability TLV to carry the TE Router IDs. IS Router CAPABILITY TLV to carry the TE Router IDs.
Sub-TLV type Length Name +==============+========+===================+
------------ ------ ----------------- | Sub-TLV type | Length | Name |
11 4 IPv4 TE Router ID +==============+========+===================+
12 16 IPv6 TE Router ID | 11 | 4 | IPv4 TE Router ID |
+--------------+--------+-------------------+
| 12 | 16 | IPv6 TE Router ID |
+--------------+--------+-------------------+
Detailed definitions of the new sub-TLVs are described in Table 2
Section 3.4.1 and 3.4.2.
3.4. Sub-TLVs for Inter-AS Reachability TLV Detailed definitions of these sub-TLVs are described in Sections
3.4.1 and 3.4.2.
3.4. Sub-TLVs for Inter-AS Reachability Information TLV
3.4.1. Remote AS Number Sub-TLV 3.4.1. Remote AS Number Sub-TLV
A new sub-TLV, the remote AS number sub-TLV, is defined for inclusion The Remote AS Number sub-TLV is defined for inclusion in the Inter-AS
in the inter-AS reachability TLV when advertising inter-AS links. Reachability Information TLV when advertising inter-AS links. The
The remote AS number sub-TLV specifies the AS number of the Remote AS Number sub-TLV specifies the AS number of the neighboring
neighboring AS to which the advertised link connects. AS to which the advertised link connects.
The remote AS number sub-TLV is TLV type 24 (see Section 6.2) and is The Remote AS Number sub-TLV is TLV type 24 (see Section 6.2) and is
4 octets in length. The format is as follows: 4 octets in length. The format 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote AS Number | | Remote AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The remote AS number field has 4 octets. When only 2 octets are used The Remote AS Number field has 4 octets. When only 2 octets are used
for the AS number, the left (high-order) 2 octets MUST be set to 0. for the AS number, the left (high-order) 2 octets MUST be set to 0.
The remote AS number sub-TLV MUST be included when a router The Remote AS Number sub-TLV MUST be included when a router
advertises an inter-AS TE link. advertises an inter-AS TE link.
3.4.2. IPv4 Remote ASBR ID Sub-TLV 3.4.2. IPv4 Remote ASBR Identifier Sub-TLV
A new sub-TLV, which is referred to as the IPv4 remote ASBR ID sub- The IPv4 Remote ASBR Identifier sub-TLV is defined for inclusion in
TLV, is defined for inclusion in the inter-AS reachability TLV when the Inter-AS Reachability Information TLV when advertising inter-AS
advertising inter-AS links. The IPv4 remote ASBR ID sub-TLV links. The IPv4 Remote ASBR Identifier sub-TLV specifies the IPv4
specifies the IPv4 identifier of the remote ASBR to which the identifier of the remote ASBR to which the advertised inter-AS link
advertised inter-AS link connects. The value advertised is selected connects. The value advertised is selected as defined in
as defined in Section 3.1. Section 3.1.
The IPv4 remote ASBR ID sub-TLV is TLV type 25 (see Section 6.2) and The IPv4 Remote ASBR Identifier sub-TLV is TLV type 25 (see
is 4 octets in length. The format of the IPv4 remote ASBR ID sub-TLV Section 6.2) and is 4 octets in length. The format of the IPv4
is as follows: Remote ASBR Identifier sub-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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID | | Remote ASBR Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The IPv4 remote ASBR ID sub-TLV MUST be included if the neighboring The IPv4 Remote ASBR Identifier sub-TLV MUST be included if the
ASBR has an IPv4 address. The value advertised is selected as neighboring ASBR has an IPv4 address. If the neighboring ASBR does
defined in Section 3.1. If the neighboring ASBR does not have an not have an IPv4 address, the IPv6 Remote ASBR Identifier sub-TLV
IPv4 address, the IPv6 remote ASBR ID sub-TLV MUST be included MUST be included instead. An IPv4 Remote ASBR Identifier sub-TLV and
instead. An IPv4 remote ASBR ID sub-TLV and IPv6 remote ASBR ID sub- IPv6 Remote ASBR Identifier sub-TLV MAY both be present in an
TLV MAY both be present in an extended IS reachability TLV. extended IS reachability TLV.
3.4.3. IPv6 Remote ASBR ID Sub-TLV 3.4.3. IPv6 Remote ASBR Identifier Sub-TLV
A new sub-TLV, which is referred to as the IPv6 remote ASBR ID sub- The IPv6 Remote ASBR Identifier sub-TLV is defined for inclusion in
TLV, is defined for inclusion in the inter-AS reachability TLV when the Inter-AS Reachability Information TLV when advertising inter-AS
advertising inter-AS links. The IPv6 remote ASBR ID sub-TLV links. The IPv6 Remote ASBR Identifier sub-TLV specifies the IPv6
specifies the IPv6 identifier of the remote ASBR to which the identifier of the remote ASBR to which the advertised inter-AS link
advertised inter-AS link connects. The value advertised is selected connects. The value advertised is selected as defined in
as defined in Section 3.1. Section 3.1.
The IPv6 remote ASBR ID sub-TLV is TLV type 26 (see Section 6.2) and The IPv6 Remote ASBR Identifier sub-TLV is TLV type 26 (see
is 16 octets in length. The format of the IPv6 remote ASBR ID sub- Section 6.2) and is 16 octets in length. The format of the IPv6
TLV is as follows: Remote ASBR Identifier sub-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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID | | Remote ASBR Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The IPv6 remote ASBR ID sub-TLV MUST be included if the neighboring The IPv6 Remote ASBR Identifier sub-TLV MUST be included if the
ASBR has an IPv6 address. If the neighboring ASBR does not have an neighboring ASBR has an IPv6 address. If the neighboring ASBR does
IPv6 address, the IPv4 remote ASBR ID sub-TLV MUST be included not have an IPv6 address, the IPv4 Remote ASBR Identifier sub-TLV
instead. An IPv4 remote ASBR ID sub-TLV and IPv6 remote ASBR ID sub- MUST be included instead. An IPv4 Remote ASBR Identifier sub-TLV and
TLV MAY both be present in an extended IS reachability TLV. IPv6 Remote ASBR Identifier sub-TLV MAY both be present in an
extended IS reachability TLV.
3.4.4. IPv6 Local ASBR ID sub-TLV 3.4.4. IPv6 Local ASBR Identifier Sub-TLV
The IPv6 Local ASBR ID sub-TLV is TLV type TBD1 (see Section 6.3) and The IPv6 Local ASBR Identifier sub-TLV is defined for inclusion in
is 16 octets in length. The format of the IPv6 Local ASBR ID sub-TLV the Inter-AS Reachability Information TLV when advertising inter-AS
is as follows: links. The IPv6 Local ASBR Identifier sub-TLV specifies the IPv6
identifier of the remote ASBR to which the advertised inter-AS link
connects. The value advertised is selected as defined in
Section 3.1.
The IPv6 Local ASBR Identifier sub-TLV is TLV type 45 (see
Section 6.2) and is 16 octets in length. The format of the IPv6
Local ASBR Identifier sub-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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local ASBR ID | | Local ASBR Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local ASBR ID (continued) | | Local ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local ASBR ID (continued) | | Local ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local ASBR ID (continued) | | Local ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The value advertised is selected as defined in Section 3.1. If the originating node does not support IPv4, the IPv6 Local ASBR
Identifier sub-TLV MUST be present in the Inter-AS Reachability
If the originating node does not support IPv4, the IPv6 Local ASBR ID Information TLV. Inter-AS Reachability Information TLVs that have a
sub-TLV MUST be present in the inter-AS reachability TLV. Inter-AS Router ID of 0.0.0.0 and do not have the IPv6 Local ASBR Identifier
reachability TLVs which have a Router ID of 0.0.0.0 and do not have sub-TLV present MUST be ignored.
the IPv6 Local ASBR ID sub-TLV present MUST be ignored.
3.5. Sub-TLVs for IS-IS Router Capability TLV 3.5. Sub-TLVs for IS-IS Router CAPABILITY TLV
3.5.1. IPv4 TE Router ID sub-TLV 3.5.1. IPv4 TE Router ID Sub-TLV
The IPv4 TE Router ID sub-TLV is TLV type 11 (see Section 6.3) and is The IPv4 TE Router ID sub-TLV is TLV type 11 (see Section 6.3) and is
4 octets in length. The format of the IPv4 TE Router ID sub-TLV is 4 octets in length. The format of the IPv4 TE Router ID sub-TLV is
as follows: 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Router ID | | TE Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The value advertised is selected as defined in Section 3.1. The value advertised is selected as defined in Section 3.1.
When the TE Router ID is needed to reach all routers within an entire When the TE Router ID is needed to reach all routers within an entire
IS-IS routing domain, the IS-IS Router capability TLV MUST be IS-IS routing domain, the IS-IS Router CAPABILITY TLV MUST be
included in its LSP. If an ASBR supports Traffic Engineering for included in its LSP. If an ASBR supports Traffic Engineering for
IPv4 and if the ASBR has an IPv4 TE Router ID, the IPv4 TE Router ID IPv4 and if the ASBR has an IPv4 TE Router ID, the IPv4 TE Router ID
sub-TLV MUST be included. If the ASBR does not have an IPv4 TE sub-TLV MUST be included. If the ASBR does not have an IPv4 TE
Router ID, the IPv6 TE Router sub-TLV MUST be included instead. An Router ID, the IPv6 TE Router ID sub-TLV MUST be included instead.
IPv4 TE Router ID sub-TLV and IPv6 TE Router ID sub-TLV MAY both be An IPv4 TE Router ID sub-TLV and IPv6 TE Router ID sub-TLV MAY both
present in an IS-IS router capability TLV. be present in an IS-IS Router CAPABILITY TLV.
3.5.2. IPv6 TE Router ID sub-TLV 3.5.2. IPv6 TE Router ID Sub-TLV
The IPv6 TE Router ID sub-TLV is TLV type 12 (see Section 6.3) and is The IPv6 TE Router ID sub-TLV is TLV type 12 (see Section 6.3) and is
16 octets in length. The format of the IPv6 TE Router ID sub-TLV is 16 octets in length. The format of the IPv6 TE Router ID sub-TLV is
as follows: 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Router ID | | TE Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Router ID (continued) | | TE Router ID (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Router ID (continued) | | TE Router ID (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Router ID (continued) | | TE Router ID (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The value advertised is selected as defined in Section 3.1. The value advertised is selected as defined in Section 3.1.
When the TE Router ID is needed to reach all routers within an entire When the TE Router ID is needed to reach all routers within an entire
IS-IS routing domain, the IS-IS router capability TLV MUST be IS-IS routing domain, the IS-IS Router CAPABILITY TLV MUST be
included in its LSP. If an ASBR supports Traffic Engineering for included in its LSP. If an ASBR supports Traffic Engineering for
IPv6 and if the ASBR has an IPv6 TE Router ID, the IPv6 TE Router ID IPv6 and if the ASBR has an IPv6 TE Router ID, the IPv6 TE Router ID
sub-TLV MUST be included. If the ASBR does not have an IPv6 TE sub-TLV MUST be included. If the ASBR does not have an IPv6 TE
Router ID, the IPv4 TE Router sub-TLV MUST be included instead. An Router ID, the IPv4 TE Router ID sub-TLV MUST be included instead.
IPv4 TE Router ID sub-TLV and IPv6 TE Router ID sub-TLV MAY both be An IPv4 TE Router ID sub-TLV and IPv6 TE Router ID sub-TLV MAY both
present in an IS-IS router capability TLV. be present in an IS-IS Router CAPABILITY TLV.
4. Procedure for Inter-AS TE Links 4. Procedure for Inter-AS TE Links
When TE is enabled on an inter-AS link and the link is up, the ASBR When TE is enabled on an inter-AS link and the link is up, the ASBR
SHOULD advertise this link using the normal procedures for [RFC5305]. SHOULD advertise this link using the normal procedures for [RFC5305].
When either the link is down or TE is disabled on the link, the ASBR When either the link is down or TE is disabled on the link, the ASBR
SHOULD withdraw the advertisement. When there are changes to the TE SHOULD withdraw the advertisement. When there are changes to the TE
parameters for the link (for example, when the available bandwidth parameters for the link (for example, when the available bandwidth
changes), the ASBR SHOULD re-advertise the link but MUST take changes), the ASBR SHOULD re-advertise the link but MUST take
precautions against excessive re-advertisements. precautions against excessive re-advertisements.
Hellos MUST NOT be exchanged over the inter-AS link, and Hellos MUST NOT be exchanged over the inter-AS link, and
consequently, an IS-IS adjacency MUST NOT be formed. consequently, an IS-IS adjacency MUST NOT be formed.
The information advertised comes from the ASBR's knowledge of the TE The information advertised comes from the ASBR's knowledge of the TE
capabilities of the link, the ASBR's knowledge of the current status capabilities of the link, the ASBR's knowledge of the current status
and usage of the link, and configuration at the ASBR of the remote AS and usage of the link, and configuration at the ASBR of the Remote AS
number and remote ASBR TE Router ID. Number and remote ASBR TE Router ID.
Legacy routers receiving an advertisement for an inter-AS TE link are Legacy routers receiving an advertisement for an inter-AS TE link are
able to ignore it because they do not know the new TLV and sub-TLVs able to ignore it because they do not know the TLV and sub-TLVs that
that are defined in Section 3 of this document. They will continue are defined in Section 3 of this document. They will continue to
to flood the LSP, but will not attempt to use the information flood the LSP but will not attempt to use the information received.
received.
In the current operation of ISIS-TE, the LSRs at each end of a TE In the current operation of IS-IS TE, the LSRs at each end of a TE
link emit LSPs describing the link. The databases in the LSRs then link emit LSPs describing the link. The databases in the LSRs then
have two entries (one locally generated, the other from the peer) have two entries (one locally generated, the other from the peer)
that describe the different 'directions' of the link. This enables that describe the different 'directions' of the link. This enables
Constrained Shortest Path First (CSPF) to do a two-way check on the Constrained Shortest Path First (CSPF) to do a two-way check on the
link when performing path computation and eliminate it from link when performing path computation and eliminate it from
consideration unless both directions of the link satisfy the required consideration unless both directions of the link satisfy the required
constraints. constraints.
In the case we are considering here (i.e., of a TE link to another In the case we are considering here (i.e., of a TE link to another
AS), there is, by definition, no IGP peering and hence no AS), there is, by definition, no IGP peering and hence no
bidirectional TE link information. In order for the CSPF route bidirectional TE link information. In order for the CSPF route
computation entity to include the link as a candidate path, we have computation entity to include the link as a candidate path, we have
to find a way to get LSPs describing its (bidirectional) TE to find a way to get LSPs describing its (bidirectional) TE
properties into the TE database. properties into the TE database.
This is achieved by the ASBR advertising, internally to its AS, This is achieved by the ASBR advertising, internally to its AS,
information about both directions of the TE link to the next AS. The information about both directions of the TE link to the next AS. The
ASBR will normally generate an LSP describing its own side of a link; ASBR will normally generate an LSP describing its own side of a link;
here we have it 'proxy' for the ASBR at the edge of the other AS and here, we have it 'proxy' for the ASBR at the edge of the other AS and
generate an additional LSP that describes that device's 'view' of the generate an additional LSP that describes that device's 'view' of the
link. link.
Only some essential TE information for the link needs to be Only some essential TE information for the link needs to be
advertised; i.e., the Interface Address, the remote AS number, and advertised, i.e., the Interface Address, the Remote AS Number, and
the remote ASBR ID of an inter-AS TE link. the Remote ASBR Identifier of an inter-AS TE link.
Routers or PCEs that are capable of processing advertisements of Routers or PCEs that are capable of processing advertisements of
inter-AS TE links SHOULD NOT use such links to compute paths that inter-AS TE links SHOULD NOT use such links to compute paths that
exit an AS to a remote ASBR and then immediately re-enter the AS exit an AS to a remote ASBR and then immediately re-enter the AS
through another TE link. Such paths would constitute extremely rare through another TE link. Such paths would constitute extremely rare
occurrences and SHOULD NOT be allowed except as the result of occurrences and SHOULD NOT be allowed except as the result of
specific policy configurations at the router or PCE computing the specific policy configurations at the router or PCE computing the
path. path.
4.1. Origin of Proxied TE Information 4.1. Origin of Proxied TE Information
Section 4 describes how an ASBR advertises TE link information as a Section 4 describes how an ASBR advertises TE link information as a
proxy for its neighbor ASBR, but does not describe where this proxy for its neighbor ASBR but does not describe where this
information comes from. information comes from.
Although the source of the information described in Section 4 is Although the source of the information described in Section 4 is
outside the scope of this document, it is possible that it will be a outside the scope of this document, it is possible that it will be a
configuration requirement at the ASBR, as are other local properties configuration requirement at the ASBR, as are other local properties
of the TE link. Further, where BGP is used to exchange IP routing of the TE link. Further, where BGP is used to exchange IP routing
information between the ASBRs, a certain amount of additional local information between the ASBRs, a certain amount of additional local
configuration about the link and the remote ASBR is likely to be configuration about the link and the remote ASBR is likely to be
available. available.
skipping to change at page 17, line 5 skipping to change at line 763
is an implementation matter. is an implementation matter.
5. Security Considerations 5. Security Considerations
The protocol extensions defined in this document are relatively minor The protocol extensions defined in this document are relatively minor
and can be secured within the AS in which they are used by the and can be secured within the AS in which they are used by the
existing IS-IS security mechanisms (e.g., using the cleartext existing IS-IS security mechanisms (e.g., using the cleartext
passwords or Hashed Message Authentication Codes, which are defined passwords or Hashed Message Authentication Codes, which are defined
in [RFC1195], [RFC5304], and [RFC5310] separately). in [RFC1195], [RFC5304], and [RFC5310] separately).
There is no exchange of information between ASes, and no change to There is no exchange of information between ASes and no change to the
the IS-IS security relationship between the ASes. In particular, IS-IS security relationship between the ASes. In particular, since
since no IS-IS adjacency is formed on the inter-AS links, there is no no IS-IS adjacency is formed on the inter-AS links, there is no
requirement for IS-IS security between the ASes. requirement for IS-IS security between the ASes.
Some of the information included in these new advertisements (e.g., Some of the information included in these advertisements (e.g., the
the remote AS number and the remote ASBR ID) is obtained manually Remote AS Number and the Remote ASBR Identifier) is obtained manually
from a neighboring administration as part of a commercial from a neighboring administration as part of a commercial
relationship. The source and content of this information should be relationship. The source and content of this information should be
carefully checked before it is entered as configuration information carefully checked before it is entered as configuration information
at the ASBR responsible for advertising the inter-AS TE links. at the ASBR responsible for advertising the inter-AS TE links.
It is worth noting that in the scenario we are considering, a Border It is worth noting that, in the scenario we are considering, a Border
Gateway Protocol (BGP) peering may exist between the two ASBRs and Gateway Protocol (BGP) peering may exist between the two ASBRs and
that this could be used to detect inconsistencies in configuration that this could be used to detect inconsistencies in configuration
(e.g., the administration that originally supplied the information (e.g., the administration that originally supplied the information
may provide incorrect information, or some manual mis-configurations may provide incorrect information, or some manual misconfigurations
or mistakes may be made by the operators). For example, if a or mistakes may be made by the operators). For example, if a
different remote AS number is received in a BGP OPEN [RFC4271] from different Remote AS Number is received in a BGP OPEN [RFC4271] from
that locally configured to ISIS-TE, as we describe here, then local that locally configured to IS-IS TE, as we describe here, then local
policy SHOULD be applied to determine whether to alert the operator policy SHOULD be applied to determine whether to alert the operator
to a potential mis-configuration or to suppress the IS-IS to a potential misconfiguration or to suppress the IS-IS
advertisement of the inter-AS TE link. Advertisement of incorrect advertisement of the inter-AS TE link. Advertisement of incorrect
information could result in an inter-AS TE LSP that traverses an information could result in an inter-AS TE LSP that traverses an
unintended AS. Note further that if BGP is used to exchange TE unintended AS. Note further that, if BGP is used to exchange TE
information as described in Section 4.1, the inter-AS BGP session information as described in Section 4.1, the inter-AS BGP session
SHOULD be secured using mechanisms such as described in [RFC5925] to SHOULD be secured using mechanisms such as described in [RFC5925] to
provide authentication and integrity checks. provide authentication and integrity checks.
For a discussion of general security considerations for IS-IS, see For a discussion of general security considerations for IS-IS, see
[RFC5304]. [RFC5304].
6. IANA Considerations 6. IANA Considerations
IANA is requested to make the following allocations from registries 6.1. Inter-AS Reachability Information TLV
under its control.
6.1. Inter-AS Reachability TLV IANA has registered the following IS-IS TLV type, described in
Section 3.1, in the "IS-IS Top-Level TLV Codepoints" registry:
This document defines the following new IS-IS TLV type, described in +=======+==============+=====+=====+=====+=======+===========+
Section 3.1, which has been registered in the IS-IS TLV codepoint | Value | Name | IIH | LSP | SNP | Purge | Reference |
registry: +=======+==============+=====+=====+=====+=======+===========+
| 141 | Inter-AS | n | y | n | n | RFC 9346 |
| | Reachability | | | | | |
| | Information | | | | | |
+-------+--------------+-----+-----+-----+-------+-----------+
Type Description IIH LSP SNP Purge Reference Table 3
---- ---------------------- --- --- --- ----- ---------
141 inter-AS reachability n y n n [This.I-D]
information
6.2. Sub-TLVs for the Inter-AS Reachability TLV 6.2. Sub-TLVs for the Inter-AS Reachability Information TLV
This document defines the following new sub-TLV types (described in IANA has registered the following sub-TLV types of top-level TLV 141
Sections 3.3.1, 3.3.2, 3.3.3, and, 3.3.4) of top-level TLV 141 (see (see Section 6.1) in the "IS-IS Sub-TLVs for TLVs Advertising
Section 6.1 above). Three of these sub-TLVs have been registered in Neighbor Information" registry. These sub-TLVs are described in
the IS-IS Sub-TLVs for TLVs Advertising Neighbor Information registry Sections 3.4.1, 3.4.2, 3.4.3, and 3.4.4.
by [RFC5316]. One additional sub-TLV (IPv6 local ASBR identifier) is
introduced by this document and needs to be added to the same
registry.
Type Description 22 23 25 141 222 223 Reference +=======+=============+====+====+====+=====+=====+=====+===========+
---- ----------------------------- --- --- --- --- --- --- --------- | Value | Description | 22 | 23 | 25 | 141 | 222 | 223 | Reference |
24 remote AS number n n n y n n [This.I-D] +=======+=============+====+====+====+=====+=====+=====+===========+
25 IPv4 remote ASBR identifier n n n y n n [This.I-D] | 24 | Remote AS | n | n | n | y | n | n | RFC 9346 |
26 IPv6 remote ASBR identifier n n n y n n [This.I-D] | | Number | | | | | | | |
TBD1 IPv6 local ASBR identifier n n n y n n [This.I-D] +-------+-------------+----+----+----+-----+-----+-----+-----------+
| 25 | IPv4 Remote | n | n | n | y | n | n | RFC 9346 |
| | ASBR | | | | | | | |
| | Identifier | | | | | | | |
+-------+-------------+----+----+----+-----+-----+-----+-----------+
| 26 | IPv6 Remote | n | n | n | y | n | n | RFC 9346 |
| | ASBR | | | | | | | |
| | Identifier | | | | | | | |
+-------+-------------+----+----+----+-----+-----+-----+-----------+
| 45 | IPv6 Local | n | n | n | y | n | n | RFC 9346 |
| | ASBR | | | | | | | |
| | Identifier | | | | | | | |
+-------+-------------+----+----+----+-----+-----+-----+-----------+
As described above in Section 3.1, the sub-TLVs which are defined in Table 4
[RFC5305], [RFC6119] and other documents for describing the TE
properties of a TE link are applicable to describe an inter-AS TE
link and MAY be included in the inter-AS reachability TLV when
adverting inter-AS TE links.
6.3. Sub-TLVs for the IS-IS Router Capability TLV As described in Section 3.1, the sub-TLVs that are defined in
[RFC5305], [RFC6119], and other documents for describing the TE
properties of a TE link are applicable to describe an inter-AS TE
link and MAY be included in the Inter-AS Reachability Information TLV
when adverting inter-AS TE links.
This document defines the following new sub-TLV types, described in 6.3. Sub-TLVs for the IS-IS Router CAPABILITY TLV
Sections 3.4.1 and 3.4.2, of top-level TLV 242 (which is defined in
[RFC7981]) that have been registered in the IS-IS Sub-TLVs for IS-IS
Router CAPABILITY TLV registry:
Type Description Reference IANA has registered the following sub-TLV types of top-level TLV 242
---- ------------------------------ --------- (see [RFC7981]) in the "IS-IS Sub-TLVs for IS-IS Router CAPABILITY
11 IPv4 TE Router ID [This.I-D] TLV" registry. These sub-TLVs are described in Sections 3.4.1 and
12 IPv6 TE Router ID [This.I-D] 3.4.2.
7. Acknowledgements +======+===================+===========+
| Type | Description | Reference |
+======+===================+===========+
| 11 | IPv4 TE Router ID | RFC 9346 |
+------+-------------------+-----------+
| 12 | IPv6 TE Router ID | RFC 9346 |
+------+-------------------+-----------+
For the original version of [RFC5316] the authors thanked Adrian Table 5
Farrel, Jean-Louis Le Roux, Christian Hopps, and Hannes Gredler for
their review and comments on this document.
8. References 7. References
8.1. Normative References 7.1. Normative References
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, DOI 10.17487/RFC1195, dual environments", RFC 1195, DOI 10.17487/RFC1195,
December 1990, <https://www.rfc-editor.org/info/rfc1195>. December 1990, <https://www.rfc-editor.org/info/rfc1195>.
[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>.
skipping to change at page 19, line 40 skipping to change at line 906
[RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions [RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions
for Advertising Router Information", RFC 7981, for Advertising Router Information", RFC 7981,
DOI 10.17487/RFC7981, October 2016, DOI 10.17487/RFC7981, October 2016,
<https://www.rfc-editor.org/info/rfc7981>. <https://www.rfc-editor.org/info/rfc7981>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
8.2. Informative References 7.2. Informative References
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>. <https://www.rfc-editor.org/info/rfc3209>.
[RFC4216] Zhang, R., Ed. and J.-P. Vasseur, Ed., "MPLS Inter- [RFC4216] Zhang, R., Ed. and J.-P. Vasseur, Ed., "MPLS Inter-
Autonomous System (AS) Traffic Engineering (TE) Autonomous System (AS) Traffic Engineering (TE)
Requirements", RFC 4216, DOI 10.17487/RFC4216, November Requirements", RFC 4216, DOI 10.17487/RFC4216, November
2005, <https://www.rfc-editor.org/info/rfc4216>. 2005, <https://www.rfc-editor.org/info/rfc4216>.
skipping to change at page 21, line 5 skipping to change at line 965
[RFC6823] Ginsberg, L., Previdi, S., and M. Shand, "Advertising [RFC6823] Ginsberg, L., Previdi, S., and M. Shand, "Advertising
Generic Information in IS-IS", RFC 6823, Generic Information in IS-IS", RFC 6823,
DOI 10.17487/RFC6823, December 2012, DOI 10.17487/RFC6823, December 2012,
<https://www.rfc-editor.org/info/rfc6823>. <https://www.rfc-editor.org/info/rfc6823>.
Appendix A. Changes to RFC 5316 Appendix A. Changes to RFC 5316
The following is a summary of the substantive changes this document The following is a summary of the substantive changes this document
makes to RFC 5316. Some editorial changes were also made. makes to RFC 5316. Some editorial changes were also made.
RFC 5316 only allowed a 32 bit Router ID in the fixed header of TLV RFC 5316 only allowed a 32-bit Router ID in the fixed header of TLV
141. This is problematic in an IPv6-only deployment where an IPv4 141. This is problematic in an IPv6-only deployment where an IPv4
address may not be available. This document specifies: address may not be available. This document specifies:
1. The Router ID should be identical to the value advertised in the 1. The Router ID should be identical to the value advertised in the
Traffic Engineering Router ID TLV (134) if available. Traffic Engineering router ID TLV (134) if available.
2. If no Traffic Engineering Router ID is assigned the Router ID 2. If no Traffic Engineering Router ID is assigned, the Router ID
should be identical to an IP Interface Address [RFC1195] advertised should be identical to an IP Interface Address [RFC1195]
by the originating IS. advertised by the originating IS.
3. If the originating node does not support IPv4, then the reserved 3. If the originating node does not support IPv4, then the reserved
value 0.0.0.0 must be used in the Router ID field and the new IPv6 value 0.0.0.0 must be used in the Router ID field and the IPv6
Local ASBR identifier sub-TLV must be present in the TLV. Local ASBR Identifier sub-TLV must be present in the TLV.
Acknowledgements
In the previous version of this document [RFC5316], the authors
thanked Adrian Farrel, Jean-Louis Le Roux, Christian Hopps, and
Hannes Gredler for their review and comments.
Authors' Addresses Authors' Addresses
Mach(Guoyi) Chen Mach(Guoyi) Chen
Huawei Huawei
Email: mach.chen@huawei.com Email: mach.chen@huawei.com
Les Ginsberg Les Ginsberg
Cisco Systems Cisco Systems
Email: ginsberg@cisco.com Email: ginsberg@cisco.com
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