rfc9300.original   rfc9300.txt 
Network Working Group D. Farinacci Internet Engineering Task Force (IETF) D. Farinacci
Internet-Draft lispers.net Request for Comments: 9300 lispers.net
Obsoletes: 6830 (if approved) V. Fuller Obsoletes: 6830 V. Fuller
Intended status: Standards Track vaf.net Internet Consulting Category: Standards Track vaf.net Internet Consulting
Expires: May 22, 2021 D. Meyer ISSN: 2070-1721 D. Meyer
1-4-5.net 1-4-5.net
D. Lewis D. Lewis
Cisco Systems Cisco Systems
A. Cabellos (Ed.) A. Cabellos, Ed.
UPC/BarcelonaTech Universitat Politecnica de Catalunya
November 18, 2020 October 2022
The Locator/ID Separation Protocol (LISP) The Locator/ID Separation Protocol (LISP)
draft-ietf-lisp-rfc6830bis-36
Abstract Abstract
This document describes the Data-Plane protocol for the Locator/ID This document describes the data plane protocol for the Locator/ID
Separation Protocol (LISP). LISP defines two namespaces, End-point Separation Protocol (LISP). LISP defines two namespaces: Endpoint
Identifiers (EIDs) that identify end-hosts and Routing Locators Identifiers (EIDs), which identify end hosts; and Routing Locators
(RLOCs) that identify network attachment points. With this, LISP (RLOCs), which identify network attachment points. With this, LISP
effectively separates control from data, and allows routers to create effectively separates control from data and allows routers to create
overlay networks. LISP-capable routers exchange encapsulated packets overlay networks. LISP-capable routers exchange encapsulated packets
according to EID-to-RLOC mappings stored in a local Map-Cache. according to EID-to-RLOC mappings stored in a local Map-Cache.
LISP requires no change to either host protocol stacks or to underlay LISP requires no change to either host protocol stacks or underlay
routers and offers Traffic Engineering, multihoming and mobility, routers and offers Traffic Engineering (TE), multihoming, and
among other features. mobility, among other features.
This document obsoletes RFC 6830. This document obsoletes RFC 6830.
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
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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 May 22, 2021. 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/rfc9300.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
1.1. Scope of Applicability . . . . . . . . . . . . . . . . . 4 1.1. Scope of Applicability
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 5 2. Requirements Notation
3. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 5 3. Definitions of Terms
4. Basic Overview . . . . . . . . . . . . . . . . . . . . . . . 8 4. Basic Overview
4.1. Deployment on the Public Internet . . . . . . . . . . . . 10 4.1. Deployment on the Public Internet
4.2. Packet Flow Sequence . . . . . . . . . . . . . . . . . . 11 4.2. Packet Flow Sequence
5. LISP Encapsulation Details . . . . . . . . . . . . . . . . . 13 5. LISP Encapsulation Details
5.1. LISP IPv4-in-IPv4 Header Format . . . . . . . . . . . . . 13 5.1. LISP IPv4-in-IPv4 Header Format
5.2. LISP IPv6-in-IPv6 Header Format . . . . . . . . . . . . . 14 5.2. LISP IPv6-in-IPv6 Header Format
5.3. Tunnel Header Field Descriptions . . . . . . . . . . . . 15 5.3. Tunnel Header Field Descriptions
6. LISP EID-to-RLOC Map-Cache . . . . . . . . . . . . . . . . . 20 6. LISP EID-to-RLOC Map-Cache
7. Dealing with Large Encapsulated Packets . . . . . . . . . . . 20 7. Dealing with Large Encapsulated Packets
7.1. A Stateless Solution to MTU Handling . . . . . . . . . . 21 7.1. A Stateless Solution to MTU Handling
7.2. A Stateful Solution to MTU Handling . . . . . . . . . . . 22 7.2. A Stateful Solution to MTU Handling
8. Using Virtualization and Segmentation with LISP . . . . . . . 23 8. Using Virtualization and Segmentation with LISP
9. Routing Locator Selection . . . . . . . . . . . . . . . . . . 23 9. Routing Locator Selection
10. Routing Locator Reachability . . . . . . . . . . . . . . . . 25 10. Routing Locator Reachability
10.1. Echo Nonce Algorithm . . . . . . . . . . . . . . . . . . 27 10.1. Echo-Nonce Algorithm
11. EID Reachability within a LISP Site . . . . . . . . . . . . . 28 11. EID Reachability within a LISP Site
12. Routing Locator Hashing . . . . . . . . . . . . . . . . . . . 28 12. Routing Locator Hashing
13. Changing the Contents of EID-to-RLOC Mappings . . . . . . . . 30 13. Changing the Contents of EID-to-RLOC Mappings
13.1. Locator-Status-Bits . . . . . . . . . . . . . . . . . . 30 13.1. Locator-Status-Bits
13.2. Database Map-Versioning . . . . . . . . . . . . . . . . 30 13.2. Database Map-Versioning
14. Multicast Considerations . . . . . . . . . . . . . . . . . . 31 14. Multicast Considerations
15. Router Performance Considerations . . . . . . . . . . . . . . 32 15. Router Performance Considerations
16. Security Considerations . . . . . . . . . . . . . . . . . . . 33 16. Security Considerations
17. Network Management Considerations . . . . . . . . . . . . . . 34 17. Network Management Considerations
18. Changes since RFC 6830 . . . . . . . . . . . . . . . . . . . 34 18. Changes since RFC 6830
19. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 19. IANA Considerations
19.1. LISP UDP Port Numbers . . . . . . . . . . . . . . . . . 35 19.1. LISP UDP Port Numbers
20. References
20. References . . . . . . . . . . . . . . . . . . . . . . . . . 35 20.1. Normative References
20.1. Normative References . . . . . . . . . . . . . . . . . . 35 20.2. Informative References
20.2. Informative References . . . . . . . . . . . . . . . . . 37 Acknowledgments
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 40 Authors' Addresses
Appendix B. Document Change Log . . . . . . . . . . . . . . . . 41
B.1. Changes to draft-ietf-lisp-rfc6830bis-27 . . . . . . . . 41
B.2. Changes to draft-ietf-lisp-rfc6830bis-27 . . . . . . . . 41
B.3. Changes to draft-ietf-lisp-rfc6830bis-26 . . . . . . . . 41
B.4. Changes to draft-ietf-lisp-rfc6830bis-25 . . . . . . . . 42
B.5. Changes to draft-ietf-lisp-rfc6830bis-24 . . . . . . . . 42
B.6. Changes to draft-ietf-lisp-rfc6830bis-23 . . . . . . . . 42
B.7. Changes to draft-ietf-lisp-rfc6830bis-22 . . . . . . . . 42
B.8. Changes to draft-ietf-lisp-rfc6830bis-21 . . . . . . . . 42
B.9. Changes to draft-ietf-lisp-rfc6830bis-20 . . . . . . . . 42
B.10. Changes to draft-ietf-lisp-rfc6830bis-19 . . . . . . . . 42
B.11. Changes to draft-ietf-lisp-rfc6830bis-18 . . . . . . . . 43
B.12. Changes to draft-ietf-lisp-rfc6830bis-17 . . . . . . . . 43
B.13. Changes to draft-ietf-lisp-rfc6830bis-16 . . . . . . . . 43
B.14. Changes to draft-ietf-lisp-rfc6830bis-15 . . . . . . . . 43
B.15. Changes to draft-ietf-lisp-rfc6830bis-14 . . . . . . . . 43
B.16. Changes to draft-ietf-lisp-rfc6830bis-13 . . . . . . . . 43
B.17. Changes to draft-ietf-lisp-rfc6830bis-12 . . . . . . . . 44
B.18. Changes to draft-ietf-lisp-rfc6830bis-11 . . . . . . . . 44
B.19. Changes to draft-ietf-lisp-rfc6830bis-10 . . . . . . . . 44
B.20. Changes to draft-ietf-lisp-rfc6830bis-09 . . . . . . . . 44
B.21. Changes to draft-ietf-lisp-rfc6830bis-08 . . . . . . . . 45
B.22. Changes to draft-ietf-lisp-rfc6830bis-07 . . . . . . . . 45
B.23. Changes to draft-ietf-lisp-rfc6830bis-06 . . . . . . . . 45
B.24. Changes to draft-ietf-lisp-rfc6830bis-05 . . . . . . . . 45
B.25. Changes to draft-ietf-lisp-rfc6830bis-04 . . . . . . . . 46
B.26. Changes to draft-ietf-lisp-rfc6830bis-03 . . . . . . . . 46
B.27. Changes to draft-ietf-lisp-rfc6830bis-02 . . . . . . . . 46
B.28. Changes to draft-ietf-lisp-rfc6830bis-01 . . . . . . . . 46
B.29. Changes to draft-ietf-lisp-rfc6830bis-00 . . . . . . . . 46
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46
1. Introduction 1. Introduction
This document describes the Locator/Identifier Separation Protocol This document describes the Locator/ID Separation Protocol (LISP).
(LISP). LISP is an encapsulation protocol built around the LISP is an encapsulation protocol built around the fundamental idea
fundamental idea of separating the topological location of a network of separating the topological location of a network attachment point
attachment point from the node's identity [CHIAPPA]. As a result from the node's identity [CHIAPPA]. As a result, LISP creates two
LISP creates two namespaces: Endpoint Identifiers (EIDs), that are namespaces: Endpoint Identifiers (EIDs), which are used to identify
used to identify end-hosts (e.g., nodes or Virtual Machines) and end hosts (e.g., nodes or Virtual Machines); and routable Routing
routable Routing Locators (RLOCs), used to identify network Locators (RLOCs), which are used to identify network attachment
attachment points. LISP then defines functions for mapping between points. LISP then defines functions for mapping between the two
the two namespaces and for encapsulating traffic originated by namespaces and for encapsulating traffic originated by devices using
devices using non-routable EIDs for transport across a network non-routable EIDs for transport across a network infrastructure that
infrastructure that routes and forwards using RLOCs. LISP routes and forwards using RLOCs. LISP encapsulation uses a dynamic
encapsulation uses a dynamic form of tunneling where no static form of tunneling where no static provisioning is required or
provisioning is required or necessary. necessary.
LISP is an overlay protocol that separates control from Data-Plane, LISP is an overlay protocol that separates control from data; this
this document specifies the Data-Plane as well as how LISP-capable document specifies the data plane as well as how LISP-capable routers
routers (Tunnel Routers) exchange packets by encapsulating them to (Tunnel Routers) exchange packets by encapsulating them to the
the appropriate location. Tunnel routers are equipped with a cache, appropriate location. Tunnel Routers are equipped with a cache,
called Map-Cache, that contains EID-to-RLOC mappings. The Map-Cache called the Map-Cache, that contains EID-to-RLOC mappings. The Map-
is populated using the LISP Control-Plane protocol Cache is populated using the LISP control plane protocol [RFC9301].
[I-D.ietf-lisp-rfc6833bis].
LISP does not require changes to either the host protocol stack or to LISP does not require changes to either the host protocol stack or
underlay routers. By separating the EID from the RLOC space, LISP underlay routers. By separating the EID from the RLOC space, LISP
offers native Traffic Engineering, multihoming and mobility, among offers native Traffic Engineering (TE), multihoming, and mobility,
other features. among other features.
Creation of LISP was initially motivated by discussions during the Creation of LISP was initially motivated by discussions during the
IAB-sponsored Routing and Addressing Workshop held in Amsterdam in IAB-sponsored Routing and Addressing Workshop held in Amsterdam in
October 2006 (see [RFC4984]). October 2006 (see [RFC4984]).
This document specifies the LISP Data-Plane encapsulation and other This document specifies the LISP data plane encapsulation and other
LISP forwarding node functionality while [I-D.ietf-lisp-rfc6833bis] LISP forwarding node functionality while [RFC9301] specifies the LISP
specifies the LISP control plane. LISP deployment guidelines can be control plane. LISP deployment guidelines can be found in [RFC7215],
found in [RFC7215] and [RFC6835] describes considerations for network and [RFC6835] describes considerations for network operational
operational management. Finally, [I-D.ietf-lisp-introduction] management. Finally, [RFC9299] describes the LISP architecture.
describes the LISP architecture.
This document obsoletes RFC 6830. This document obsoletes RFC 6830.
1.1. Scope of Applicability 1.1. Scope of Applicability
LISP was originally developed to address the Internet-wide route LISP was originally developed to address the Internet-wide route
scaling problem [RFC4984]. While there are a number of approaches of scaling problem [RFC4984]. While there are a number of approaches of
interest for that problem, as LISP as been developed and refined, a interest for that problem, as LISP has been developed and refined, a
large number of other LISP uses have been found and are being used. large number of other ways to use LISP have been found and are being
As such, the design and development of LISP has changed so as to implemented. As such, the design and development of LISP have
focus on these use cases. The common property of these uses is a changed so as to focus on these use cases. The common property of
large set of cooperating entities seeking to communicate over the these uses is a large set of cooperating entities seeking to
public Internet or other large underlay IP infrastructures, while communicate over the public Internet or other large underlay IP
keeping the addressing and topology of the cooperating entities infrastructures while keeping the addressing and topology of the
separate from the underlay and Internet topology, routing, and cooperating entities separate from the underlay and Internet
addressing. topology, routing, and addressing.
2. Requirements Notation 2. Requirements Notation
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.
3. Definition of Terms 3. Definitions of Terms
Address Family Identifier (AFI): AFI is a term used to describe an Address Family Identifier (AFI): "AFI" is a term used to describe an
address encoding in a packet. An address family that pertains to address encoding in a packet. An address family is an address
addresses found in Data-Plane headers. See [AFN] and [RFC3232] format found in data plane packet headers, for example, an IPv4
for details. An AFI value of 0 used in this specification address or an IPv6 address. See [AFN], [RFC2453], [RFC2677], and
indicates an unspecified encoded address where the length of the [RFC4760] for details. An AFI value of 0 used in this
address is 0 octets following the 16-bit AFI value of 0. specification indicates an unspecified encoded address where the
length of the address is 0 octets following the 16-bit AFI value
of 0.
Anycast Address: Anycast Address refers to the same IPv4 or IPv6 Anycast Address: "Anycast address" refers to the same IPv4 or IPv6
address configured and used on multiple systems at the same time. address configured and used on multiple systems at the same time.
An EID or RLOC can be an anycast address in each of their own An EID or RLOC can be an anycast address in each of their own
address spaces. address spaces.
Client-side: Client-side is a term used in this document to indicate Client-side: "Client-side" is a term used in this document to
a connection initiation attempt by an end-system represented by an indicate a connection initiation attempt by an end-system
EID. represented by an EID.
Egress Tunnel Router (ETR): An ETR is a router that accepts an IP Egress Tunnel Router (ETR): An ETR is a router that accepts an IP
packet where the destination address in the "outer" IP header is packet where the destination address in the "outer" IP header is
one of its own RLOCs. The router strips the "outer" header and one of its own RLOCs. The router strips the "outer" header and
forwards the packet based on the next IP header found. In forwards the packet based on the next IP header found. In
general, an ETR receives LISP-encapsulated IP packets from the general, an ETR receives LISP-encapsulated IP packets from the
Internet on one side and sends decapsulated IP packets to site Internet on one side and sends decapsulated IP packets to site
end-systems on the other side. ETR functionality does not have to end-systems on the other side. ETR functionality does not have to
be limited to a router device. A server host can be the endpoint be limited to a router device. A server host can be the endpoint
of a LISP tunnel as well. of a LISP tunnel as well.
EID-to-RLOC Database: The EID-to-RLOC Database is a distributed EID-to-RLOC Database: The EID-to-RLOC Database is a distributed
database that contains all known EID-Prefix-to-RLOC mappings. database that contains all known EID-Prefix-to-RLOC mappings.
Each potential ETR typically contains a small piece of the Each potential ETR typically contains a small piece of the
database: the EID-to-RLOC mappings for the EID-Prefixes "behind" database: the EID-to-RLOC mappings for the EID-Prefixes "behind"
the router. These map to one of the router's own IP addresses the router. These map to one of the router's own IP addresses
that are routable on the underlay. Note that there MAY be that are routable on the underlay. Note that there MAY be
transient conditions when the EID-Prefix for the LISP site and transient conditions when the EID-Prefix for the LISP site and
Locator-Set for each EID-Prefix may not be the same on all ETRs. Locator-Set for each EID-Prefix may not be the same on all ETRs.
This has no negative implications, since a partial set of Locators This has no negative implications, since a partial set of Locators
can be used. can be used.
EID-to-RLOC Map-Cache: The EID-to-RLOC Map-Cache is generally EID-to-RLOC Map-Cache: The EID-to-RLOC Map-Cache is a generally
short-lived, on-demand table in an ITR that stores, tracks, and is short-lived, on-demand table in an Ingress Tunnel Router (ITR)
responsible for timing out and otherwise validating EID-to-RLOC that stores, tracks, and is responsible for timing out and
mappings. This cache is distinct from the full "database" of EID- otherwise validating EID-to-RLOC mappings. This cache is distinct
to-RLOC mappings; it is dynamic, local to the ITR(s), and from the full "database" of EID-to-RLOC mappings; it is dynamic,
relatively small, while the database is distributed, relatively local to the ITR(s), and relatively small, while the database is
static, and much more widely scoped to LISP nodes. distributed, relatively static, and much more widely scoped to
LISP nodes.
EID-Prefix: An EID-Prefix is a power-of-two block of EIDs that are EID-Prefix: An EID-Prefix is a power-of-two block of EIDs that are
allocated to a site by an address allocation authority. EID- allocated to a site by an address allocation authority. EID-
Prefixes are associated with a set of RLOC addresses. EID-Prefix Prefixes are associated with a set of RLOC addresses. EID-Prefix
allocations can be broken up into smaller blocks when an RLOC set allocations can be broken up into smaller blocks when an RLOC-Set
is to be associated with the larger EID-Prefix block. is to be associated with the larger EID-Prefix block.
End-System: An end-system is an IPv4 or IPv6 device that originates End-System: An end-system is an IPv4 or IPv6 device that originates
packets with a single IPv4 or IPv6 header. The end-system packets with a single IPv4 or IPv6 header. The end-system
supplies an EID value for the destination address field of the IP supplies an EID value for the destination address field of the IP
header when communicating outside of its routing domain. An end- header when communicating outside of its routing domain. An end-
system can be a host computer, a switch or router device, or any system can be a host computer, a switch or router device, or any
network appliance. network appliance.
Endpoint ID (EID): An EID is a 32-bit (for IPv4) or 128-bit (for Endpoint ID (EID): An EID is a 32-bit (for IPv4) or 128-bit (for
IPv6) value that identifies a host. EIDs are generally only found IPv6) value that identifies a host. EIDs are generally only found
in the source and destination address fields of the first (most in the source and destination address fields of the first
inner) LISP header of a packet. The host obtains a destination (innermost) LISP header of a packet. The host obtains a
EID the same way it obtains a destination address today, for destination EID through a Domain Name System (DNS) [RFC1034]
example, through a Domain Name System (DNS) [RFC1034] lookup or lookup or Session Initiation Protocol (SIP) [RFC3261] exchange.
Session Initiation Protocol (SIP) [RFC3261] exchange. The source This behavior does not change when LISP is in use. The source EID
EID is obtained via existing mechanisms used to set a host's is obtained via existing mechanisms used to set a host's "local"
"local" IP address. An EID used on the public Internet MUST have IP address. An EID used on the public Internet MUST have the same
the same properties as any other IP address used in that manner; properties as any other IP address used in that manner; this
this means, among other things, that it MUST be unique. An EID is means, among other things, that it MUST be unique. An EID is
allocated to a host from an EID-Prefix block associated with the allocated to a host from an EID-Prefix block associated with the
site where the host is located. An EID can be used by a host to site where the host is located. An EID can be used by a host to
refer to other hosts. Note that EID blocks MAY be assigned in a refer to other hosts. Note that EID blocks MAY be assigned in a
hierarchical manner, independent of the network topology, to hierarchical manner, independent of the network topology, to
facilitate scaling of the mapping database. In addition, an EID facilitate scaling of the mapping database. In addition, an EID
block assigned to a site MAY have site-local structure block assigned to a site MAY have site-local structure
(subnetting) for routing within the site; this structure is not (subnetting) for routing within the site; this structure is not
visible to the underlay routing system. In theory, the bit string visible to the underlay routing system. In theory, the bit string
that represents an EID for one device can represent an RLOC for a that represents an EID for one device can represent an RLOC for a
different device. When used in discussions with other Locator/ID different device. When discussing other Locator/ID separation
separation proposals, a LISP EID will be called an "LEID". proposals, any references to an EID in this document will refer to
Throughout this document, any references to "EID" refer to an a LISP EID.
LEID.
Ingress Tunnel Router (ITR): An ITR is a router that resides in a Ingress Tunnel Router (ITR): An ITR is a router that resides in a
LISP site. Packets sent by sources inside of the LISP site to LISP site. Packets sent by sources inside of the LISP site to
destinations outside of the site are candidates for encapsulation destinations outside of the site are candidates for encapsulation
by the ITR. The ITR treats the IP destination address as an EID by the ITR. The ITR treats the IP destination address as an EID
and performs an EID-to-RLOC mapping lookup. The router then and performs an EID-to-RLOC mapping lookup. The router then
prepends an "outer" IP header with one of its routable RLOCs (in prepends an "outer" IP header with one of its routable RLOCs (in
the RLOC space) in the source address field and the result of the the RLOC space) in the source address field and the result of the
mapping lookup in the destination address field. Note that this mapping lookup in the destination address field. Note that this
destination RLOC may be an intermediate, proxy device that has destination RLOC may be an intermediate, proxy device that has
better knowledge of the EID-to-RLOC mapping closer to the better knowledge of the EID-to-RLOC mapping closer to the
destination EID. In general, an ITR receives IP packets from site destination EID. In general, an ITR receives IP packets from site
end-systems on one side and sends LISP-encapsulated IP packets end-systems on one side and sends LISP-encapsulated IP packets
toward the Internet on the other side. toward the Internet on the other side.
LISP Header: LISP header is a term used in this document to refer LISP Header: "LISP header" is a term used in this document to refer
to the outer IPv4 or IPv6 header, a UDP header, and a LISP- to the outer IPv4 or IPv6 header, a UDP header, and a LISP-
specific 8-octet header that follow the UDP header and that an ITR specific 8-octet header, all of which follow the UDP header. An
prepends or an ETR strips. ITR prepends LISP headers on packets, and an ETR strips them.
LISP Router: A LISP router is a router that performs the functions LISP Router: A LISP router is a router that performs the functions
of any or all of the following: ITR, ETR, RTR, Proxy-ITR (PITR), of any or all of the following: ITRs, ETRs, Re-encapsulating
or Proxy-ETR (PETR). Tunneling Routers (RTRs), Proxy-ITRs (PITRs), or Proxy-ETRs
(PETRs).
LISP Site: LISP site is a set of routers in an edge network that are LISP Site: A LISP site is a set of routers in an edge network that
under a single technical administration. LISP routers that reside are under a single technical administration. LISP routers that
in the edge network are the demarcation points to separate the reside in the edge network are the demarcation points to separate
edge network from the core network. the edge network from the core network.
Locator-Status-Bits (LSBs): Locator-Status-Bits are present in the Locator-Status-Bits (LSBs): Locator-Status-Bits are present in the
LISP header. They are used by ITRs to inform ETRs about the up/ LISP header. They are used by ITRs to inform ETRs about the up/
down status of all ETRs at the local site. These bits are used as down status of all ETRs at the local site. These bits are used as
a hint to convey up/down router status and not path reachability a hint to convey up/down router status and not path reachability
status. The LSBs can be verified by use of one of the Locator status. The LSBs can be verified by use of one of the Locator
reachability algorithms described in Section 10. An ETR MUST reachability algorithms described in Section 10. An ETR MUST rate
rate-limit the action it takes when it detects changes in the limit the action it takes when it detects changes in the Locator-
Locator-Status-Bits. Status-Bits.
Proxy-ETR (PETR): A PETR is defined and described in [RFC6832]. A Proxy-ETR (PETR): A PETR is defined and described in [RFC6832]. A
PETR acts like an ETR but does so on behalf of LISP sites that PETR acts like an ETR but does so on behalf of LISP sites that
send packets to destinations at non-LISP sites. send packets to destinations at non-LISP sites.
Proxy-ITR (PITR): A PITR is defined and described in [RFC6832]. A Proxy-ITR (PITR): A PITR is defined and described in [RFC6832]. A
PITR acts like an ITR but does so on behalf of non-LISP sites that PITR acts like an ITR but does so on behalf of non-LISP sites that
send packets to destinations at LISP sites. send packets to destinations at LISP sites.
Recursive Tunneling: Recursive Tunneling occurs when a packet has Recursive Tunneling: Recursive Tunneling occurs when a packet has
more than one LISP IP header. Additional layers of tunneling MAY more than one LISP IP header. Additional layers of tunneling MAY
be employed to implement Traffic Engineering or other re-routing be employed to implement Traffic Engineering or other rerouting as
as needed. When this is done, an additional "outer" LISP header needed. When this is done, an additional "outer" LISP header is
is added, and the original RLOCs are preserved in the "inner" added, and the original RLOCs are preserved in the "inner" header.
header.
Re-Encapsulating Tunneling Router (RTR): An RTR acts like an ETR to Re-encapsulating Tunneling Router (RTR): An RTR acts like an ETR to
remove a LISP header, then acts as an ITR to prepend a new LISP remove a LISP header, then acts as an ITR to prepend a new LISP
header. This is known as Re-encapsulating Tunneling. Doing this header. This is known as Re-encapsulating Tunneling. Doing this
allows a packet to be re-routed by the RTR without adding the allows a packet to be rerouted by the RTR without adding the
overhead of additional tunnel headers. When using multiple overhead of additional tunnel headers. When using multiple
mapping database systems, care must be taken to not create re- mapping database systems, care must be taken to not create re-
encapsulation loops through misconfiguration. encapsulation loops through misconfiguration.
Route-Returnability: Route-returnability is an assumption that the Route-Returnability: Route-returnability is an assumption that the
underlying routing system will deliver packets to the destination. underlying routing system will deliver packets to the destination.
When combined with a nonce that is provided by a sender and When combined with a nonce that is provided by a sender and
returned by a receiver, this limits off-path data insertion. A returned by a receiver, this limits off-path data insertion. A
route-returnability check is verified when a message is sent with route-returnability check is verified when a message is sent with
a nonce, another message is returned with the same nonce, and the a nonce, another message is returned with the same nonce, and the
destination of the original message appears as the source of the destination of the original message appears as the source of the
returned message. returned message.
Routing Locator (RLOC): An RLOC is an IPv4 [RFC0791] or IPv6 Routing Locator (RLOC): An RLOC is an IPv4 address [RFC0791] or IPv6
[RFC8200] address of an Egress Tunnel Router (ETR). An RLOC is address [RFC8200] of an Egress Tunnel Router (ETR). An RLOC is
the output of an EID-to-RLOC mapping lookup. An EID maps to zero the output of an EID-to-RLOC mapping lookup. An EID maps to zero
or more RLOCs. Typically, RLOCs are numbered from blocks that are or more RLOCs. Typically, RLOCs are numbered from blocks that are
assigned to a site at each point to which it attaches to the assigned to a site at each point to which it attaches to the
underlay network; where the topology is defined by the underlay network, where the topology is defined by the
connectivity of provider networks. Multiple RLOCs can be assigned connectivity of provider networks. Multiple RLOCs can be assigned
to the same ETR device or to multiple ETR devices at a site. to the same ETR device or to multiple ETR devices at a site.
Server-side: Server-side is a term used in this document to indicate Server-side: "Server-side" is a term used in this document to
that a connection initiation attempt is being accepted for a indicate that a connection initiation attempt is being accepted
destination EID. for a destination EID.
xTR: An xTR is a reference to an ITR or ETR when direction of data xTR: An xTR is a reference to an ITR or ETR when direction of data
flow is not part of the context description. "xTR" refers to the flow is not part of the context description. "xTR" refers to the
router that is the tunnel endpoint and is used synonymously with router that is the tunnel endpoint and is used synonymously with
the term "Tunnel Router". For example, "An xTR can be located at the term "Tunnel Router". For example, "An xTR can be located at
the Customer Edge (CE) router" indicates both ITR and ETR the Customer Edge (CE) router" indicates both ITR and ETR
functionality at the CE router. functionality at the CE router.
4. Basic Overview 4. Basic Overview
One key concept of LISP is that end-systems operate the same way they One key concept of LISP is that end-systems operate the same way when
do today. The IP addresses that hosts use for tracking sockets and LISP is not in use as well as when LISP is in use. The IP addresses
connections, and for sending and receiving packets, do not change. that hosts use for tracking sockets and connections, and for sending
In LISP terminology, these IP addresses are called Endpoint and receiving packets, do not change. In LISP terminology, these IP
Identifiers (EIDs). addresses are called Endpoint Identifiers (EIDs).
Routers continue to forward packets based on IP destination Routers continue to forward packets based on IP destination
addresses. When a packet is LISP encapsulated, these addresses are addresses. When a packet is LISP encapsulated, these addresses are
referred to as Routing Locators (RLOCs). Most routers along a path referred to as RLOCs. Most routers along a path between two hosts
between two hosts will not change; they continue to perform routing/ will not change; they continue to perform routing/forwarding lookups
forwarding lookups on the destination addresses. For routers between on the destination addresses. For routers between the source host
the source host and the ITR as well as routers from the ETR to the and the ITR as well as routers from the ETR to the destination host,
destination host, the destination address is an EID. For the routers the destination address is an EID. For the routers between the ITR
between the ITR and the ETR, the destination address is an RLOC. and the ETR, the destination address is an RLOC.
Another key LISP concept is the "Tunnel Router". A Tunnel Router Another key LISP concept is the "Tunnel Router". A Tunnel Router
prepends LISP headers on host-originated packets and strips them prepends LISP headers on host-originated packets and strips them
prior to final delivery to their destination. The IP addresses in prior to final delivery to their destination. The IP addresses in
this "outer header" are RLOCs. During end-to-end packet exchange this "outer header" are RLOCs. During end-to-end packet exchange
between two Internet hosts, an ITR prepends a new LISP header to each between two Internet hosts, an ITR prepends a new LISP header to each
packet, and an ETR strips the new header. The ITR performs EID-to- packet, and an ETR strips the new header. The ITR performs EID-to-
RLOC lookups to determine the routing path to the ETR, which has the RLOC lookups to determine the routing path to the ETR, which has the
RLOC as one of its IP addresses. RLOC as one of its IP addresses.
Some basic rules governing LISP are: Some basic rules governing LISP are:
o End-systems only send to addresses that are EIDs. EIDs are * End-systems only send to addresses that are EIDs. EIDs are
typically IP addresses assigned to hosts (other types of EID are typically IP addresses assigned to hosts (other types of EIDs are
supported by LISP, see [RFC8060] for further information). End- supported by LISP; see [RFC8060] for further information). End-
systems don't know that addresses are EIDs versus RLOCs but assume systems don't know that addresses are EIDs versus RLOCs but assume
that packets get to their intended destinations. In a system that packets get to their intended destinations. In a system
where LISP is deployed, LISP routers intercept EID-addressed where LISP is deployed, LISP routers intercept EID-addressed
packets and assist in delivering them across the network core packets and assist in delivering them across the network core
where EIDs cannot be routed. The procedure a host uses to send IP where EIDs cannot be routed. The procedure a host uses to send IP
packets does not change. packets does not change.
o LISP routers mostly deal with Routing Locator addresses. See * LISP routers prepend and strip outer headers with RLOC addresses.
details in Section 4.2 to clarify what is meant by "mostly". See Section 4.2 for details.
o RLOCs are always IP addresses assigned to routers, preferably * RLOCs are always IP addresses assigned to routers, preferably
topologically oriented addresses from provider CIDR (Classless topologically oriented addresses from provider Classless Inter-
Inter-Domain Routing) blocks. Domain Routing (CIDR) blocks.
o When a router originates packets, it MAY use as a source address * When a router originates packets, it MAY use as a source address
either an EID or RLOC. When acting as a host (e.g., when either an EID or RLOC. When acting as a host (e.g., when
terminating a transport session such as Secure SHell (SSH), terminating a transport session such as Secure Shell (SSH),
TELNET, or the Simple Network Management Protocol (SNMP)), it MAY TELNET, or the Simple Network Management Protocol (SNMP)), it MAY
use an EID that is explicitly assigned for that purpose. An EID use an EID that is explicitly assigned for that purpose. An EID
that identifies the router as a host MUST NOT be used as an RLOC; that identifies the router as a host MUST NOT be used as an RLOC;
an EID is only routable within the scope of a site. A typical BGP an EID is only routable within the scope of a site. A typical BGP
configuration might demonstrate this "hybrid" EID/RLOC usage where configuration might demonstrate this "hybrid" EID/RLOC usage where
a router could use its "host-like" EID to terminate iBGP sessions a router could use its "host-like" EID to terminate internal BGP
to other routers in a site while at the same time using RLOCs to (iBGP) sessions to other routers in a site while at the same time
terminate eBGP sessions to routers outside the site. using RLOCs to terminate external BGP (eBGP) sessions to routers
outside the site.
o Packets with EIDs in them are not expected to be delivered end-to- * Packets with EIDs in them are not expected to be delivered end to
end in the absence of an EID-to-RLOC mapping operation. They are end in the absence of an EID-to-RLOC mapping operation. They are
expected to be used locally for intra-site communication or to be expected to be used locally for intra-site communication or to be
encapsulated for inter-site communication. encapsulated for inter-site communication.
o EIDs MAY also be structured (subnetted) in a manner suitable for * EIDs MAY also be structured (subnetted) in a manner suitable for
local routing within an Autonomous System (AS). local routing within an Autonomous System (AS).
An additional LISP header MAY be prepended to packets by a TE-ITR An additional LISP header MAY be prepended to packets by a TE-ITR
when re-routing of the path for a packet is desired. A potential when rerouting of the path for a packet is desired. A potential use
use-case for this would be an ISP router that needs to perform case for this would be an ISP router that needs to perform Traffic
Traffic Engineering for packets flowing through its network. In such Engineering for packets flowing through its network. In such a
a situation, termed "Recursive Tunneling", an ISP transit acts as an situation, termed "Recursive Tunneling", an ISP transit acts as an
additional ITR, and the destination RLOC it uses for the new additional ITR, and the destination RLOC it uses for the new
prepended header would be either a TE-ETR within the ISP (along an prepended header would be either a TE-ETR within the ISP (along an
intra-ISP traffic engineered path) or a TE-ETR within another ISP (an intra-ISP traffic-engineered path) or a TE-ETR within another ISP (an
inter-ISP traffic engineered path, where an agreement to build such a inter-ISP traffic-engineered path, where an agreement to build such a
path exists). path exists).
In order to avoid excessive packet overhead as well as possible In order to avoid excessive packet overhead as well as possible
encapsulation loops, this document RECOMMENDS that a maximum of two encapsulation loops, it is RECOMMENDED that a maximum of two LISP
LISP headers can be prepended to a packet. For initial LISP headers can be prepended to a packet. For initial LISP deployments,
deployments, it is assumed that two headers is sufficient, where the it is assumed that two headers is sufficient, where the first
first prepended header is used at a site for Location/Identity prepended header is used at a site for separation of location and
separation and the second prepended header is used inside a service identity and the second prepended header is used inside a service
provider for Traffic Engineering purposes. provider for Traffic Engineering purposes.
Tunnel Routers can be placed fairly flexibly in a multi-AS topology. Tunnel Routers can be placed fairly flexibly in a multi-AS topology.
For example, the ITR for a particular end-to-end packet exchange For example, the ITR for a particular end-to-end packet exchange
might be the first-hop or default router within a site for the source might be the first-hop or default router within a site for the source
host. Similarly, the ETR might be the last-hop router directly host. Similarly, the ETR might be the last-hop router directly
connected to the destination host. Another example, perhaps for a connected to the destination host. As another example, perhaps for a
VPN service outsourced to an ISP by a site, the ITR could be the VPN service outsourced to an ISP by a site, the ITR could be the
site's border router at the service provider attachment point. site's border router at the service provider attachment point.
Mixing and matching of site-operated, ISP-operated, and other Tunnel Mixing and matching of site-operated, ISP-operated, and other Tunnel
Routers is allowed for maximum flexibility. Routers is allowed for maximum flexibility.
4.1. Deployment on the Public Internet 4.1. Deployment on the Public Internet
Several of the mechanisms in this document are intended for Several of the mechanisms in this document are intended for
deployment in controlled, trusted environments, and are insecure for deployment in controlled, trusted environments and are insecure for
use over the public Internet. In particular, on the public internet use over the public Internet. In particular, on the public Internet,
xTRs: xTRs:
o MUST set the N, L, E, and V bits in the LISP header (Section 5.1) * MUST set the N-, L-, E-, and V-bits in the LISP header
to zero. (Section 5.1) to zero.
o MUST NOT use Locator-Status-Bits and echo-nonce, as described in * MUST NOT use Locator-Status-Bits and Echo-Nonce, as described in
Section 10 for Routing Locator Reachability. Instead MUST rely Section 10, for RLOC reachability. Instead, they MUST rely solely
solely on control-plane methods. on control plane methods.
o MUST NOT use Gleaning or Locator-Status-Bits and Map-Versioning, * MUST NOT use gleaning or Locator-Status-Bits and Map-Versioning,
as described in Section 13 to update the EID-to-RLOC Mappings. as described in Section 13, to update the EID-to-RLOC mappings.
Instead relying solely on control-plane methods. Instead, they MUST rely solely on control plane methods.
4.2. Packet Flow Sequence 4.2. Packet Flow Sequence
This section provides an example of the unicast packet flow, This section provides an example of the unicast packet flow, also
including also Control-Plane information as specified in including control plane information as specified in [RFC9301]. The
[I-D.ietf-lisp-rfc6833bis]. The example also assumes the following example also assumes the following conditions:
conditions:
o Source host "host1.abc.example.com" is sending a packet to * Source host "host1.abc.example.com" is sending a packet to
"host2.xyz.example.com", exactly as it would if the site was not "host2.xyz.example.com", exactly as it would if the site was not
not using LISP. using LISP.
o Each site is multihomed, so each Tunnel Router has an address * Each site is multihomed, so each Tunnel Router has an address
(RLOC) assigned from the service provider address block for each (RLOC) assigned from the service provider address block for each
provider to which that particular Tunnel Router is attached. provider to which that particular Tunnel Router is attached.
o The ITR(s) and ETR(s) are directly connected to the source and * The ITR(s) and ETR(s) are directly connected to the source and
destination, respectively, but the source and destination can be destination, respectively, but the source and destination can be
located anywhere in the LISP site. located anywhere in the LISP site.
o A Map-Request is sent for an external destination when the * A Map-Request is sent for an external destination when the
destination is not found in the forwarding table or matches a destination is not found in the forwarding table or matches a
default route. Map-Requests are sent to the mapping database default route. Map-Requests are sent to the mapping database
system by using the LISP Control-Plane protocol documented in system by using the LISP control plane protocol documented in
[I-D.ietf-lisp-rfc6833bis]. [RFC9301].
o Map-Replies are sent on the underlying routing system topology * Map-Replies are sent on the underlying routing system topology,
using the [I-D.ietf-lisp-rfc6833bis] Control-Plane protocol. using the control plane protocol [RFC9301].
Client host1.abc.example.com wants to communicate with server Client host1.abc.example.com wants to communicate with server
host2.xyz.example.com: host2.xyz.example.com:
1. host1.abc.example.com wants to open a TCP connection to 1. host1.abc.example.com wants to open a TCP connection to
host2.xyz.example.com. It does a DNS lookup on host2.xyz.example.com. It does a DNS lookup on
host2.xyz.example.com. An A/AAAA record is returned. This host2.xyz.example.com. An A/AAAA record is returned. This
address is the destination EID. The locally assigned address of address is the destination EID. The locally assigned address of
host1.abc.example.com is used as the source EID. An IPv4 or IPv6 host1.abc.example.com is used as the source EID. An IPv4 or IPv6
packet is built and forwarded through the LISP site as a normal packet is built and forwarded through the LISP site as a normal
IP packet until it reaches a LISP ITR. IP packet until it reaches a LISP ITR.
2. The LISP ITR must be able to map the destination EID to an RLOC 2. The LISP ITR must be able to map the destination EID to an RLOC
of one of the ETRs at the destination site. A method to do this of one of the ETRs at the destination site. A method for doing
is to send a LISP Map-Request, as specified in this is to send a LISP Map-Request, as specified in [RFC9301].
[I-D.ietf-lisp-rfc6833bis].
3. The mapping system helps forwarding the Map-Request to the 3. The Mapping System helps forward the Map-Request to the
corresponding ETR. When the Map-Request arrives at one of the corresponding ETR. When the Map-Request arrives at one of the
ETRs at the destination site, it will process the packet as a ETRs at the destination site, it will process the packet as a
control message. control message.
4. The ETR looks at the destination EID of the Map-Request and 4. The ETR looks at the destination EID of the Map-Request and
matches it against the prefixes in the ETR's configured EID-to- matches it against the prefixes in the ETR's configured EID-to-
RLOC mapping database. This is the list of EID-Prefixes the ETR RLOC mapping database. This is the list of EID-Prefixes the ETR
is supporting for the site it resides in. If there is no match, is supporting for the site it resides in. If there is no match,
the Map-Request is dropped. Otherwise, a LISP Map-Reply is the Map-Request is dropped. Otherwise, a LISP Map-Reply is
returned to the ITR. returned to the ITR.
skipping to change at page 12, line 42 skipping to change at line 525
to a different ETR than the one that returned the Map-Reply due to a different ETR than the one that returned the Map-Reply due
to the source site's hashing policy or the destination site's to the source site's hashing policy or the destination site's
Locator-Set policy. Locator-Set policy.
7. The ETR receives these packets directly (since the destination 7. The ETR receives these packets directly (since the destination
address is one of its assigned IP addresses), checks the validity address is one of its assigned IP addresses), checks the validity
of the addresses, strips the LISP header, and forwards packets to of the addresses, strips the LISP header, and forwards packets to
the attached destination host. the attached destination host.
8. In order to defer the need for a mapping lookup in the reverse 8. In order to defer the need for a mapping lookup in the reverse
direction, an ETR can OPTIONALLY create a cache entry that maps direction, it is OPTIONAL for an ETR to create a cache entry that
the source EID (inner-header source IP address) to the source maps the source EID (inner-header source IP address) to the
RLOC (outer-header source IP address) in a received LISP packet. source RLOC (outer-header source IP address) in a received LISP
Such a cache entry is termed a "glean mapping" and only contains packet. Such a cache entry is termed a "glean mapping" and only
a single RLOC for the EID in question. More complete information contains a single RLOC for the EID in question. More complete
about additional RLOCs SHOULD be verified by sending a LISP Map- information about additional RLOCs SHOULD be verified by sending
Request for that EID. Both the ITR and the ETR MAY also a LISP Map-Request for that EID. Both the ITR and the ETR MAY
influence the decision the other makes in selecting an RLOC. also influence the decision the other makes in selecting an RLOC.
5. LISP Encapsulation Details 5. LISP Encapsulation Details
Since additional tunnel headers are prepended, the packet becomes Since additional tunnel headers are prepended, the packet becomes
larger and can exceed the MTU of any link traversed from the ITR to larger and can exceed the MTU of any link traversed from the ITR to
the ETR. It is RECOMMENDED in IPv4 that packets do not get the ETR. It is RECOMMENDED in IPv4 that packets do not get
fragmented as they are encapsulated by the ITR. Instead, the packet fragmented as they are encapsulated by the ITR. Instead, the packet
is dropped and an ICMP Unreachable/Fragmentation-Needed message is is dropped and an ICMPv4 Unreachable / Fragmentation Needed message
returned to the source. is returned to the source.
In the case when fragmentation is needed, this specification In the case when fragmentation is needed, it is RECOMMENDED that
RECOMMENDS that implementations provide support for one of the implementations provide support for one of the proposed fragmentation
proposed fragmentation and reassembly schemes. Two existing schemes and reassembly schemes. Two existing schemes are detailed in
are detailed in Section 7. Section 7.
Since IPv4 or IPv6 addresses can be either EIDs or RLOCs, the LISP Since IPv4 or IPv6 addresses can be either EIDs or RLOCs, the LISP
architecture supports IPv4 EIDs with IPv6 RLOCs (where the inner architecture supports IPv4 EIDs with IPv6 RLOCs (where the inner
header is in IPv4 packet format and the outer header is in IPv6 header is in IPv4 packet format and the outer header is in IPv6
packet format) or IPv6 EIDs with IPv4 RLOCs (where the inner header packet format) or IPv6 EIDs with IPv4 RLOCs (where the inner header
is in IPv6 packet format and the outer header is in IPv4 packet is in IPv6 packet format and the outer header is in IPv4 packet
format). The next sub-sections illustrate packet formats for the format). The next sub-sections illustrate packet formats for the
homogeneous case (IPv4-in-IPv4 and IPv6-in-IPv6), but all 4 homogeneous case (IPv4-in-IPv4 and IPv6-in-IPv6), but all 4
combinations MUST be supported. Additional types of EIDs are defined combinations MUST be supported. Additional types of EIDs are defined
in [RFC8060]. in [RFC8060].
As LISP uses UDP encapsulation to carry traffic between xTRs across As LISP uses UDP encapsulation to carry traffic between xTRs across
the Internet, implementors should be aware of the provisions of the Internet, implementors should be aware of the provisions of
[RFC8085], especially those given in section 3.1.11 on congestion [RFC8085], especially those given in its Section 3.1.11 on congestion
control for UDP tunneling. control for UDP tunneling.
Implementors are encouraged to consider UDP checksum usage guidelines Implementors are encouraged to consider UDP checksum usage guidelines
in section 3.4 of [RFC8085] when it is desirable to protect UDP and in Section 3.4 of [RFC8085] when it is desirable to protect UDP and
LISP headers against corruption. LISP headers against corruption.
5.1. LISP IPv4-in-IPv4 Header Format 5.1. LISP IPv4-in-IPv4 Header Format
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ |Version| IHL | DSCP |ECN| Total Length | / |Version| IHL | DSCP |ECN| Total Length |
/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Identification |Flags| Fragment Offset | | | Identification |Flags| Fragment Offset |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
OH | Time to Live | Protocol = 17 | Header Checksum | OH | Time to Live | Protocol = 17 | Header Checksum |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Source Routing Locator | | | Source Routing Locator |
skipping to change at page 15, line 46 skipping to change at line 659
r + + r + +
| | | |
^ + Destination EID + ^ + Destination EID +
\ | | \ | |
\ + + \ + +
\ | | \ | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.3. Tunnel Header Field Descriptions 5.3. Tunnel Header Field Descriptions
Inner Header (IH): The inner header is the header on the Inner Header (IH): The inner header is the header on the datagram
datagram received from the originating host [RFC0791] [RFC8200] received from the originating host [RFC0791] [RFC8200] [RFC2474].
[RFC2474]. The source and destination IP addresses are EIDs. The source and destination IP addresses are EIDs.
Outer Header: (OH) The outer header is a new header prepended by an Outer Header (OH): The outer header is a new header prepended by an
ITR. The address fields contain RLOCs obtained from the ingress ITR. The address fields contain RLOCs obtained from the ingress
router's EID-to-RLOC Cache. The IP protocol number is "UDP (17)" router's EID-to-RLOC Map-Cache. The IP protocol number is "UDP
from [RFC0768]. The setting of the Don't Fragment (DF) bit (17)" from [RFC0768]. The setting of the Don't Fragment (DF) bit
'Flags' field is according to rules listed in Sections 7.1 and 'Flags' field is according to rules listed in Sections 7.1 and
7.2. 7.2.
UDP Header: The UDP header contains an ITR selected source port when UDP Header: The UDP header contains an ITR-selected source port when
encapsulating a packet. See Section 12 for details on the hash encapsulating a packet. See Section 12 for details on the hash
algorithm used to select a source port based on the 5-tuple of the algorithm used to select a source port based on the 5-tuple of the
inner header. The destination port MUST be set to the well-known inner header. The destination port MUST be set to the well-known
IANA-assigned port value 4341. IANA-assigned port value 4341.
UDP Checksum: The 'UDP Checksum' field SHOULD be transmitted as zero UDP Checksum: The 'UDP Checksum' field SHOULD be transmitted as zero
by an ITR for either IPv4 [RFC0768] and IPv6 encapsulation by an ITR for either IPv4 [RFC0768] or IPv6 encapsulation
[RFC6935] [RFC6936]. When a packet with a zero UDP checksum is [RFC6935] [RFC6936]. When a packet with a zero UDP checksum is
received by an ETR, the ETR MUST accept the packet for received by an ETR, the ETR MUST accept the packet for
decapsulation. When an ITR transmits a non-zero value for the UDP decapsulation. When an ITR transmits a non-zero value for the UDP
checksum, it MUST send a correctly computed value in this field. checksum, it MUST send a correctly computed value in this field.
When an ETR receives a packet with a non-zero UDP checksum, it MAY When an ETR receives a packet with a non-zero UDP checksum, it MAY
choose to verify the checksum value. If it chooses to perform choose to verify the checksum value. If it chooses to perform
such verification, and the verification fails, the packet MUST be such verification and the verification fails, the packet MUST be
silently dropped. If the ETR chooses not to perform the silently dropped. If the ETR either chooses not to perform the
verification, or performs the verification successfully, the verification or performs the verification successfully, the packet
packet MUST be accepted for decapsulation. The handling of UDP MUST be accepted for decapsulation. The handling of UDP zero
zero checksums over IPv6 for all tunneling protocols, including checksums over IPv6 for all tunneling protocols, including LISP,
LISP, is subject to the applicability statement in [RFC6936]. is subject to the applicability statement in [RFC6936].
UDP Length: The 'UDP Length' field is set for an IPv4-encapsulated UDP Length: The 'UDP Length' field is set for an IPv4-encapsulated
packet to be the sum of the inner-header IPv4 Total Length plus packet to be the sum of the inner-header IPv4 Total Length plus
the UDP and LISP header lengths. For an IPv6-encapsulated packet, the UDP and LISP header lengths. For an IPv6-encapsulated packet,
the 'UDP Length' field is the sum of the inner-header IPv6 Payload the 'UDP Length' field is the sum of the inner-header IPv6 Payload
Length, the size of the IPv6 header (40 octets), and the size of Length, the size of the IPv6 header (40 octets), and the size of
the UDP and LISP headers. the UDP and LISP headers.
N: The N-bit is the nonce-present bit. When this bit is set to 1, N: The N-bit is the nonce-present bit. When this bit is set to 1,
the low-order 24 bits of the first 32 bits of the LISP header the low-order 24 bits of the first 32 bits of the LISP header
contain a Nonce. See Section 10.1 for details. Both N- and contain a nonce. See Section 10.1 for details. Both N- and
V-bits MUST NOT be set in the same packet. If they are, a V-bits MUST NOT be set in the same packet. If they are, a
decapsulating ETR MUST treat the 'Nonce/Map-Version' field as decapsulating ETR MUST treat the 'Nonce/Map-Version' field as
having a Nonce value present. having a nonce value present.
L: The L-bit is the 'Locator-Status-Bits' field enabled bit. When L: The L-bit is the 'Locator-Status-Bits' field enabled bit. When
this bit is set to 1, the Locator-Status-Bits in the second this bit is set to 1, the Locator-Status-Bits in the second
32 bits of the LISP header are in use. 32 bits of the LISP header are in use.
x 1 x x 0 x x x x 1 x x 0 x x x
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|N|L|E|V|I|R|K|K| Nonce/Map-Version | |N|L|E|V|I|R|K|K| Nonce/Map-Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Locator-Status-Bits | | Locator-Status-Bits |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E: The E-bit is the echo-nonce-request bit. This bit MUST be ignored E: The E-bit is the Echo-Nonce-request bit. This bit MUST be
and has no meaning when the N-bit is set to 0. When the N-bit is ignored and has no meaning when the N-bit is set to 0. When the
set to 1 and this bit is set to 1, an ITR is requesting that the N-bit is set to 1 and this bit is set to 1, an ITR is requesting
nonce value in the 'Nonce' field be echoed back in LISP- that the nonce value in the 'Nonce' field be echoed back in LISP-
encapsulated packets when the ITR is also an ETR. See encapsulated packets when the ITR is also an ETR. See
Section 10.1 for details. Section 10.1 for details.
V: The V-bit is the Map-Version present bit. When this bit is set to V: The V-bit is the Map-Version present bit. When this bit is set
1, the N-bit MUST be 0. Refer to Section 13.2 for more details. to 1, the N-bit MUST be 0. Refer to [RFC9302] for more details on
This bit indicates that the LISP header is encoded in this Database Map-Versioning. This bit indicates that the LISP header
case as: is encoded in this case as:
0 x 0 1 x x x x 0 x 0 1 x x x x
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|N|L|E|V|I|R|K|K| Source Map-Version | Dest Map-Version | |N|L|E|V|I|R|K|K| Source Map-Version | Dest Map-Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance ID/Locator-Status-Bits | | Instance ID/Locator-Status-Bits |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
I: The I-bit is the Instance ID bit. See Section 8 for more details. I: The I-bit is the Instance ID bit. See Section 8 for more
When this bit is set to 1, the 'Locator-Status-Bits' field is details. When this bit is set to 1, the 'Locator-Status-Bits'
reduced to 8 bits and the high-order 24 bits are used as an field is reduced to 8 bits and the high-order 24 bits are used as
Instance ID. If the L-bit is set to 0, then the low-order 8 bits an Instance ID. If the L-bit is set to 0, then the low-order
are transmitted as zero and ignored on receipt. The format of the 8 bits are transmitted as zero and ignored on receipt. The format
LISP header would look like this: of the LISP header would look like this:
x x x x 1 x x x x x x x 1 x x x
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|N|L|E|V|I|R|K|K| Nonce/Map-Version | |N|L|E|V|I|R|K|K| Nonce/Map-Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance ID | LSBs | | Instance ID | LSBs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
R: The R-bit is a Reserved and unassigned bit for future use. It R: The R-bit is a reserved and unassigned bit for future use. It
MUST be set to 0 on transmit and MUST be ignored on receipt. MUST be set to 0 on transmit and MUST be ignored on receipt.
KK: The KK-bits are a 2-bit field used when encapsulated packets are KK: The KK-bits are a 2-bit field used when encapsulated packets are
encrypted. The field is set to 00 when the packet is not encrypted. The field is set to 00 when the packet is not
encrypted. See [RFC8061] for further information. encrypted. See [RFC8061] for further information.
LISP Nonce: The LISP 'Nonce' field is a 24-bit value that is LISP Nonce: The LISP 'Nonce' field is a 24-bit value that is
randomly generated by an ITR when the N-bit is set to 1. Nonce randomly generated by an ITR when the N-bit is set to 1. Nonce
generation algorithms are an implementation matter but are generation algorithms are an implementation matter but are
required to generate different nonces when sending to different required to generate different nonces when sending to different
RLOCs. The nonce is also used when the E-bit is set to request RLOCs. The nonce is also used when the E-bit is set to request
the nonce value to be echoed by the other side when packets are the nonce value to be echoed by the other side when packets are
returned. When the E-bit is clear but the N-bit is set, a remote returned. When the E-bit is clear but the N-bit is set, a remote
ITR is either echoing a previously requested echo-nonce or ITR is either echoing a previously requested Echo-Nonce or
providing a random nonce. See Section 10.1 for more details. providing a random nonce. See Section 10.1 for more details.
Finally, when both the N and V-bit are not set (N=0, V=0), then Finally, when both the N- and V-bits are not set (N=0, V=0), then
both the Nonce and Map-Version fields are set to 0 and ignored on both the 'Nonce' and 'Map-Version' fields are set to 0 and ignored
receipt. on receipt.
LISP Locator-Status-Bits (LSBs): When the L-bit is also set, the LISP Locator-Status-Bits (LSBs): When the L-bit is also set, the
'Locator-Status-Bits' field in the LISP header is set by an ITR to 'Locator-Status-Bits' field in the LISP header is set by an ITR to
indicate to an ETR the up/down status of the Locators in the indicate to an ETR the up/down status of the Locators in the
source site. Each RLOC in a Map-Reply is assigned an ordinal source site. Each RLOC in a Map-Reply is assigned an ordinal
value from 0 to n-1 (when there are n RLOCs in a mapping entry). value from 0 to n-1 (when there are n RLOCs in a mapping entry).
The Locator-Status-Bits are numbered from 0 to n-1 from the least The Locator-Status-Bits are numbered from 0 to n-1 from the least
significant bit of the field. The field is 32 bits when the I-bit significant bit of the field. The field is 32 bits when the I-bit
is set to 0 and is 8 bits when the I-bit is set to 1. When a is set to 0 and is 8 bits when the I-bit is set to 1. When a
Locator-Status-Bit is set to 1, the ITR is indicating to the ETR Locator-Status-Bit is set to 1, the ITR is indicating to the ETR
skipping to change at page 18, line 39 skipping to change at line 790
the ETRs at the same site. When a site has multiple EID-Prefixes the ETRs at the same site. When a site has multiple EID-Prefixes
that result in multiple mappings (where each could have a that result in multiple mappings (where each could have a
different Locator-Set), the Locator-Status-Bits setting in an different Locator-Set), the Locator-Status-Bits setting in an
encapsulated packet MUST reflect the mapping for the EID-Prefix encapsulated packet MUST reflect the mapping for the EID-Prefix
that the inner-header source EID address matches (longest-match). that the inner-header source EID address matches (longest-match).
If the LSB for an anycast Locator is set to 1, then there is at If the LSB for an anycast Locator is set to 1, then there is at
least one RLOC with that address, and the ETR is considered 'up'. least one RLOC with that address, and the ETR is considered 'up'.
When doing ITR/PITR encapsulation: When doing ITR/PITR encapsulation:
o The outer-header 'Time to Live' field (or 'Hop Limit' field, in * The outer-header 'Time to Live' field (or 'Hop Limit' field, in
the case of IPv6) SHOULD be copied from the inner-header 'Time to the case of IPv6) SHOULD be copied from the inner-header 'Time to
Live' field. Live' field.
o The outer-header IPv4 'Differentiated Services Code Point' (DSCP) * The outer-header IPv4 'Differentiated Services Code Point (DSCP)'
field or the 'Traffic Class' field, in the case of IPv6, SHOULD be field (or 'Traffic Class' field, in the case of IPv6) SHOULD be
copied from the inner-header IPv4 DSCP field or 'Traffic Class' copied from the inner-header IPv4 'DSCP' field (or 'Traffic Class'
field in the case of IPv6, to the outer-header. Guidelines for field, in the case of IPv6) to the outer header. Guidelines for
this can be found at [RFC2983]. this can be found in [RFC2983].
o The IPv4 'Explicit Congestion Notification' (ECN) field and bits 6 * The IPv4 'Explicit Congestion Notification (ECN)' field and bits 6
and 7 of the IPv6 'Traffic Class' field requires special treatment and 7 of the IPv6 'Traffic Class' field require special treatment
in order to avoid discarding indications of congestion as in order to avoid discarding indications of congestion as
specified in [RFC6040]. specified in [RFC6040].
When doing ETR/PETR decapsulation: When doing ETR/PETR decapsulation:
o The inner-header IPv4 'Time to Live' field or 'Hop Limit' field in * The inner-header IPv4 'Time to Live' field (or 'Hop Limit' field,
the case of IPv6, MUST be copied from the outer-header 'Time to in the case of IPv6) MUST be copied from the outer-header 'Time to
Live'/'Hop Limit' field, when the 'Time to Live'/'Hop Limit' value Live'/'Hop Limit' field when the Time to Live / Hop Limit value of
of the outer header is less than the 'Time to Live'/'Hop Limit' the outer header is less than the Time to Live / Hop Limit value
value of the inner header. Failing to perform this check can of the inner header. Failing to perform this check can cause the
cause the 'Time to Live'/'Hop Limit' of the inner header to Time to Live / Hop Limit of the inner header to increment across
increment across encapsulation/decapsulation cycles. This check encapsulation/decapsulation cycles. This check is also performed
is also performed when doing initial encapsulation, when a packet when doing initial encapsulation, when a packet comes to an ITR or
comes to an ITR or PITR destined for a LISP site. PITR destined for a LISP site.
o The outer-header IPv4 'Differentiated Services Code Point' (DSCP) * The outer-header IPv4 'Differentiated Services Code Point (DSCP)'
field or the 'Traffic Class' field in the case of IPv6, SHOULD be field (or 'Traffic Class' field, in the case of IPv6) SHOULD be
copied from the outer-header IPv4 DSCP field or 'Traffic Class' copied from the outer-header 'IPv4 DSCP' field (or 'Traffic Class'
field in the case of IPv6, to the inner-header. Guidelines for field, in the case of IPv6) to the inner header. Guidelines for
this can be found at [RFC2983]. this can be found in [RFC2983].
o The IPv4 'Explicit Congestion Notification' (ECN) field and bits 6 * The IPv4 'Explicit Congestion Notification (ECN)' field and bits 6
and 7 of the IPv6 'Traffic Class' field, requires special and 7 of the IPv6 'Traffic Class' field require special treatment
treatment in order to avoid discarding indications of congestion in order to avoid discarding indications of congestion as
as specified in [RFC6040]. Note that implementations exist that specified in [RFC6040]. Note that implementations exist that copy
copy the 'ECN' field from the outer header to the inner header the 'ECN' field from the outer header to the inner header, even
even though [RFC6040] does not recommend this behavior. It is though [RFC6040] does not recommend this behavior. It is
RECOMMENDED that implementations change to support the behavior in RECOMMENDED that implementations change to support the behavior
[RFC6040]. discussed in [RFC6040].
Note that if an ETR/PETR is also an ITR/PITR and chooses to re- Note that if an ETR/PETR is also an ITR/PITR and chooses to re-
encapsulate after decapsulating, the net effect of this is that the encapsulate after decapsulating, the net effect of this is that the
new outer header will carry the same Time to Live as the old outer new outer header will carry the same Time to Live as the old outer
header minus 1. header minus 1.
Copying the Time to Live (TTL) serves two purposes: first, it Copying the Time to Live serves two purposes: first, it preserves the
preserves the distance the host intended the packet to travel; distance the host intended the packet to travel; second, and more
second, and more importantly, it provides for suppression of looping importantly, it provides for suppression of looping packets in the
packets in the event there is a loop of concatenated tunnels due to event there is a loop of concatenated tunnels due to
misconfiguration. misconfiguration.
Some xTRs and PxTRs performs re-encapsulation operations and need to Some xTRs, PETRs, and PITRs perform re-encapsulation operations and
treat the 'Explicit Congestion Notification' (ECN) in a special way. need to treat ECN functions in a special way. Because the re-
Because the re-encapsulation operation is a sequence of two encapsulation operation is a sequence of two operations, namely a
operations, namely a decapsulation followed by an encapsulation, the decapsulation followed by an encapsulation, the ECN bits MUST be
ECN bits MUST be treated as described above for these two operations. treated as described above for these two operations.
The LISP dataplane protocol is not backwards compatible with The LISP data plane protocol is not backwards compatible with
[RFC6830] and does not have explicit support for introducing future [RFC6830] and does not have explicit support for introducing future
protocol changes (e.g. an explicit version field). However, the LISP protocol changes (e.g., an explicit version field). However, the
control plane [I-D.ietf-lisp-rfc6833bis] allows an ETR to register LISP control plane [RFC9301] allows an ETR to register data plane
dataplane capabilities by means of new LCAF types [RFC8060]. In this capabilities by means of new LISP Canonical Address Format (LCAF)
way an ITR can be made aware of the dataplane capabilities of an ETR, types [RFC8060]. In this way, an ITR can be made aware of the data
and encapsulate accordingly. The specification of the new LCAF plane capabilities of an ETR and encapsulate accordingly. The
types, new LCAF mechanisms, and their use, is out of the scope of specification of the new LCAF types, the new LCAF mechanisms, and
this document. their use are out of the scope of this document.
6. LISP EID-to-RLOC Map-Cache 6. LISP EID-to-RLOC Map-Cache
ITRs and PITRs maintain an on-demand cache, referred as LISP EID-to- ITRs and PITRs maintain an on-demand cache, referred to as the LISP
RLOC Map-Cache, that contains mappings from EID-prefixes to locator EID-to-RLOC Map-Cache, that contains mappings from EID-Prefixes to
sets. The cache is used to encapsulate packets from the EID space to Locator-Sets. The cache is used to encapsulate packets from the EID
the corresponding RLOC network attachment point. space to the corresponding RLOC network attachment point.
When an ITR/PITR receives a packet from inside of the LISP site to When an ITR/PITR receives a packet from inside of the LISP site to
destinations outside of the site a longest-prefix match lookup of the destinations outside of the site, a longest-prefix match lookup of
EID is done to the Map-Cache. the EID is done to the Map-Cache.
When the lookup succeeds, the Locator-Set retrieved from the Map- When the lookup succeeds, the Locator-Set retrieved from the Map-
Cache is used to send the packet to the EID's topological location. Cache is used to send the packet to the EID's topological location.
If the lookup fails, the ITR/PITR needs to retrieve the mapping using If the lookup fails, the ITR/PITR needs to retrieve the mapping using
the LISP Control-Plane protocol [I-D.ietf-lisp-rfc6833bis]. While the LISP control plane protocol [RFC9301]. While the mapping is
the mapping is being retrieved, the ITR/PITR can either drop or being retrieved, the ITR/PITR can either drop or buffer the packets.
buffer the packets. This document does not have specific This document does not have specific recommendations about the action
recommendations about the action to be taken. It is up to the to be taken. It is up to the deployer to consider whether or not it
deployer to consider whether or not it is desirable to buffer packets is desirable to buffer packets and deploy a LISP implementation that
and deploy a LISP implementation that offers the desired behaviour. offers the desired behavior. Once the mapping is resolved, it is
Once the mapping is resolved it is then stored in the local Map-Cache then stored in the local Map-Cache to forward subsequent packets
to forward subsequent packets addressed to the same EID-prefix. addressed to the same EID-Prefix.
The Map-Cache is a local cache of mappings, entries are expired based The Map-Cache is a local cache of mappings; entries are expired based
on the associated Time to live. In addition, entries can be updated on the associated Time to Live. In addition, entries can be updated
with more current information, see Section 13 for further information with more current information; see Section 13 for further information
on this. Finally, the Map-Cache also contains reachability on this. Finally, the Map-Cache also contains reachability
information about EIDs and RLOCs, and uses LISP reachability information about EIDs and RLOCs and uses LISP reachability
information mechanisms to determine the reachability of RLOCs, see information mechanisms to determine the reachability of RLOCs; see
Section 10 for the specific mechanisms. Section 10 for the specific mechanisms.
7. Dealing with Large Encapsulated Packets 7. Dealing with Large Encapsulated Packets
This section proposes two mechanisms to deal with packets that exceed This section proposes two mechanisms to deal with packets that exceed
the path MTU between the ITR and ETR. the Path MTU (PMTU) between the ITR and ETR.
It is left to the implementor to decide if the stateless or stateful It is left to the implementor to decide if the stateless or stateful
mechanism SHOULD be implemented. Both or neither can be used, since mechanism SHOULD be implemented. Both or neither can be used, since
it is a local decision in the ITR regarding how to deal with MTU it is a local decision in the ITR regarding how to deal with MTU
issues, and sites can interoperate with differing mechanisms. issues, and sites can interoperate with differing mechanisms.
Both stateless and stateful mechanisms also apply to Re-encapsulating Both stateless and stateful mechanisms also apply to Re-encapsulating
and Recursive Tunneling, so any actions below referring to an ITR and Recursive Tunneling, so any actions below referring to an ITR
also apply to a TE-ITR. also apply to a TE-ITR.
skipping to change at page 21, line 21 skipping to change at line 917
An ITR stateless solution to handle MTU issues is described as An ITR stateless solution to handle MTU issues is described as
follows: follows:
1. Define H to be the size, in octets, of the outer header an ITR 1. Define H to be the size, in octets, of the outer header an ITR
prepends to a packet. This includes the UDP and LISP header prepends to a packet. This includes the UDP and LISP header
lengths. lengths.
2. Define L to be the size, in octets, of the maximum-sized packet 2. Define L to be the size, in octets, of the maximum-sized packet
an ITR can send to an ETR without the need for the ITR or any an ITR can send to an ETR without the need for the ITR or any
intermediate routers to fragment the packet. The network intermediate routers to fragment the packet. The network
administrator of the LISP deployment has to determine what is the administrator of the LISP deployment has to determine what the
suitable value of L so to make sure that no MTU issues arise. suitable value of L is, so as to make sure that no MTU issues
arise.
3. Define an architectural constant S for the maximum size of a 3. Define an architectural constant S for the maximum size of a
packet, in octets, an ITR MUST receive from the source so the packet, in octets, an ITR MUST receive from the source so the
effective MTU can be met. That is, L = S + H. effective MTU can be met. That is, L = S + H.
When an ITR receives a packet from a site-facing interface and adds H When an ITR receives a packet from a site-facing interface and adds H
octets worth of encapsulation to yield a packet size greater than L octets worth of encapsulation to yield a packet size greater than L
octets (meaning the received packet size was greater than S octets octets (meaning the received packet size was greater than S octets
from the source), it resolves the MTU issue by first splitting the from the source), it resolves the MTU issue by first splitting the
original packet into 2 equal-sized fragments. A LISP header is then original packet into 2 equal-sized fragments. A LISP header is then
prepended to each fragment. The size of the encapsulated fragments prepended to each fragment. The size of the encapsulated fragments
is then (S/2 + H), which is less than the ITR's estimate of the path is then (S/2 + H), which is less than the ITR's estimate of the PMTU
MTU between the ITR and its correspondent ETR. between the ITR and its correspondent ETR.
When an ETR receives encapsulated fragments, it treats them as two When an ETR receives encapsulated fragments, it treats them as two
individually encapsulated packets. It strips the LISP headers and individually encapsulated packets. It strips the LISP headers and
then forwards each fragment to the destination host of the then forwards each fragment to the destination host of the
destination site. The two fragments are reassembled at the destination site. The two fragments are reassembled at the
destination host into the single IP datagram that was originated by destination host into the single IP datagram that was originated by
the source host. Note that reassembly can happen at the ETR if the the source host. Note that reassembly can happen at the ETR if the
encapsulated packet was fragmented at or after the ITR. encapsulated packet was fragmented at or after the ITR.
This behavior MUST be performed by the ITR only when the source host This behavior MUST be implemented by the ITR only when the source
originates a packet with the 'DF' field of the IP header set to 0. host originates a packet with the 'DF' field of the IP header set to
When the 'DF' field of the IP header is set to 1, or the packet is an 0. When the 'DF' field of the IP header is set to 1 or the packet is
IPv6 packet originated by the source host, the ITR will drop the an IPv6 packet originated by the source host, the ITR will drop the
packet when the size (adding in the size of the encapsulation header) packet when the size (adding in the size of the encapsulation header)
is greater than L and send an ICMPv4 ICMP Unreachable/Fragmentation- is greater than L and send an ICMPv4 Unreachable / Fragmentation
Needed or ICMPv6 "Packet Too Big" message to the source with a value Needed or ICMPv6 Packet Too Big (PTB) message to the source with a
of S, where S is (L - H). value of S, where S is (L - H).
When the outer-header encapsulation uses an IPv4 header, an When the outer-header encapsulation uses an IPv4 header, an
implementation SHOULD set the DF bit to 1 so ETR fragment reassembly implementation SHOULD set the DF bit to 1 so ETR fragment reassembly
can be avoided. An implementation MAY set the DF bit in such headers can be avoided. An implementation MAY set the DF bit in such headers
to 0 if it has good reason to believe there are unresolvable path MTU to 0 if it has good reason to believe there are unresolvable PMTU
issues between the sending ITR and the receiving ETR. issues between the sending ITR and the receiving ETR.
This specification RECOMMENDS that L be defined as 1500. Additional It is RECOMMENDED that L be defined as 1500. Additional information
information about in-network MTU and fragmentation issues can be about in-network MTU and fragmentation issues can be found in
found at [RFC4459]. [RFC4459].
7.2. A Stateful Solution to MTU Handling 7.2. A Stateful Solution to MTU Handling
An ITR stateful solution to handle MTU issues is described as An ITR stateful solution to handle MTU issues is described as
follows: follows:
1. The ITR will keep state of the effective MTU for each Locator per 1. The ITR will keep state of the effective MTU for each Locator per
Map-Cache entry. The effective MTU is what the core network can Map-Cache entry. The effective MTU is what the core network can
deliver along the path between the ITR and ETR. deliver along the path between the ITR and ETR.
2. When an IPv4-encapsulated packet with the DF bit set to 1, 2. When an IPv4-encapsulated packet with the DF bit set to 1 exceeds
exceeds what the core network can deliver, one of the what the core network can deliver, one of the intermediate
intermediate routers on the path will send an an ICMPv4 routers on the path will send an ICMPv4 Unreachable /
Unreachable/Fragmentation-Needed to the ITR, respectively. The Fragmentation Needed message to the ITR. The ITR will parse the
ITR will parse the ICMP message to determine which Locator is ICMP message to determine which Locator is affected by the
affected by the effective MTU change and then record the new effective MTU change and then record the new effective MTU value
effective MTU value in the Map-Cache entry. in the Map-Cache entry.
3. When a packet is received by the ITR from a source inside of the 3. When a packet is received by the ITR from a source inside of the
site and the size of the packet is greater than the effective MTU site and the size of the packet is greater than the effective MTU
stored with the Map-Cache entry associated with the destination stored with the Map-Cache entry associated with the destination
EID the packet is for, the ITR will send an ICMPv4 ICMP EID the packet is for, the ITR will send an ICMPv4 Unreachable /
Unreachable/Fragmentation-Needed message back to the source. The Fragmentation Needed message back to the source. The packet size
packet size advertised by the ITR in the ICMP message is the advertised by the ITR in the ICMP message is the effective MTU
effective MTU minus the LISP encapsulation length. minus the LISP encapsulation length.
Even though this mechanism is stateful, it has advantages over the Even though this mechanism is stateful, it has advantages over the
stateless IP fragmentation mechanism, by not involving the stateless IP fragmentation mechanism, by not involving the
destination host with reassembly of ITR fragmented packets. destination host with reassembly of ITR fragmented packets.
Please note that [RFC1191] and [RFC1981], which describe the use of Please note that using ICMP packets for PMTU discovery, as described
ICMP packets for PMTU discovery, can behave suboptimally in the in [RFC1191] and [RFC8201], can result in suboptimal behavior in the
presence of ICMP black holes or off-path attackers that spoof ICMP. presence of ICMP packet losses or off-path attackers that spoof ICMP.
Possible mitigations include ITRs and ETRs cooperating on MTU probe Possible mitigations include ITRs and ETRs cooperating on MTU probe
packets ([RFC4821], [I-D.ietf-tsvwg-datagram-plpmtud]), or ITRs packets [RFC4821] [RFC8899] or ITRs storing the beginning of large
storing the beginning of large packets to verify that they match the packets to verify that they match the echoed packet in an ICMP
echoed packet in ICMP Frag Needed/PTB. Fragmentation Needed / PTB message.
8. Using Virtualization and Segmentation with LISP 8. Using Virtualization and Segmentation with LISP
There are several cases where segregation is needed at the EID level. There are several cases where segregation is needed at the EID level.
For instance, this is the case for deployments containing overlapping For instance, this is the case for deployments containing overlapping
addresses, traffic isolation policies or multi-tenant virtualization. addresses, traffic isolation policies, or multi-tenant
For these and other scenarios where segregation is needed, Instance virtualization. For these and other scenarios where segregation is
IDs are used. needed, Instance IDs are used.
An Instance ID can be carried in a LISP-encapsulated packet. An ITR An Instance ID can be carried in a LISP-encapsulated packet. An ITR
that prepends a LISP header will copy a 24-bit value used by the LISP that prepends a LISP header will copy a 24-bit value used by the LISP
router to uniquely identify the address space. The value is copied router to uniquely identify the address space. The value is copied
to the 'Instance ID' field of the LISP header, and the I-bit is set to the 'Instance ID' field of the LISP header, and the I-bit is set
to 1. to 1.
When an ETR decapsulates a packet, the Instance ID from the LISP When an ETR decapsulates a packet, the Instance ID from the LISP
header is used as a table identifier to locate the forwarding table header is used as a table identifier to locate the forwarding table
to use for the inner destination EID lookup. to use for the inner destination EID lookup.
For example, an 802.1Q VLAN tag or VPN identifier could be used as a For example, an 802.1Q VLAN tag or VPN identifier could be used as a
24-bit Instance ID. See [I-D.ietf-lisp-vpn] for LISP VPN use-case 24-bit Instance ID. See [LISP-VPN] for details regarding LISP VPN
details. Please note that the Instance ID is not protected, an on- use cases. Please note that the Instance ID is not protected; an on-
path attacker can modify the tags and for instance, allow path attacker can modify the tags and, for instance, allow
communicatons between logically isolated VLANs. communications between logically isolated VLANs.
Participants within a LISP deployment must agree on the meaning of Participants within a LISP deployment must agree on the meaning of
Instance ID values. The source and destination EIDs MUST belong to Instance ID values. The source and destination EIDs MUST belong to
the same Instance ID. the same Instance ID.
Instance ID SHOULD NOT be used with overlapping IPv6 EID addresses. The Instance ID SHOULD NOT be used with overlapping IPv6 EID
addresses.
9. Routing Locator Selection 9. Routing Locator Selection
The Map-Cache contains the state used by ITRs and PITRs to The Map-Cache contains the state used by ITRs and PITRs to
encapsulate packets. When an ITR/PITR receives a packet from inside encapsulate packets. When an ITR/PITR receives a packet from inside
the LISP site to a destination outside of the site a longest-prefix the LISP site to a destination outside of the site, a longest-prefix
match lookup of the EID is done to the Map-Cache (see Section 6). match lookup of the EID is done to the Map-Cache (see Section 6).
The lookup returns a single Locator-Set containing a list of RLOCs The lookup returns a single Locator-Set containing a list of RLOCs
corresponding to the EID's topological location. Each RLOC in the corresponding to the EID's topological location. Each RLOC in the
Locator-Set is associated with a 'Priority' and 'Weight', this Locator-Set is associated with a Priority and Weight; this
information is used to select the RLOC to encapsulate. information is used to select the RLOC to encapsulate.
The RLOC with the lowest 'Priority' is selected. An RLOC with The RLOC with the lowest Priority is selected. An RLOC with Priority
'Priority' 255 means that MUST NOT be used for forwarding. When 255 means that it MUST NOT be used for forwarding. When multiple
multiple RLOCs have the same 'Priority' then the 'Weight' states how RLOCs have the same Priority, then the Weight states how to load-
to load balance traffic among them. The value of the 'Weight' balance traffic among them. The value of the Weight represents the
represents the relative weight of the total packets that match the relative weight of the total packets that match the mapping entry.
mapping entry.
The following are different scenarios for choosing RLOCs and the The following are different scenarios for choosing RLOCs and the
controls that are available: controls that are available:
o The server-side returns one RLOC. The client-side can only use * The server-side returns one RLOC. The client-side can only use
one RLOC. The server-side has complete control of the selection. one RLOC. The server-side has complete control of the selection.
o The server-side returns a list of RLOCs where a subset of the list * The server-side returns a list of RLOCs where a subset of the list
has the same best Priority. The client can only use the subset has the same best Priority. The client can only use the subset
list according to the weighting assigned by the server-side. In list according to the weighting assigned by the server-side. In
this case, the server-side controls both the subset list and load- this case, the server-side controls both the subset list and load
splitting across its members. The client-side can use RLOCs splitting across its members. The client-side can use RLOCs
outside of the subset list if it determines that the subset list outside of the subset list if it determines that the subset list
is unreachable (unless RLOCs are set to a Priority of 255). Some is unreachable (unless RLOCs are set to a Priority of 255). Some
sharing of control exists: the server-side determines the sharing of control exists: the server-side determines the
destination RLOC list and load distribution while the client-side destination RLOC list and load distribution while the client-side
has the option of using alternatives to this list if RLOCs in the has the option of using alternatives to this list if RLOCs in the
list are unreachable. list are unreachable.
o The server-side sets a Weight of zero for the RLOC subset list. * The server-side sets a Weight of zero for the RLOC subset list.
In this case, the client-side can choose how the traffic load is In this case, the client-side can choose how the traffic load is
spread across the subset list. See Section 12 for details on spread across the subset list. See Section 12 for details on
load-sharing mechanisms. Control is shared by the server-side load-sharing mechanisms. Control is shared by the server-side
determining the list and the client-side determining load determining the list and the client-side determining load
distribution. Again, the client can use alternative RLOCs if the distribution. Again, the client can use alternative RLOCs if the
server-provided list of RLOCs is unreachable. server-provided list of RLOCs is unreachable.
o Either side (more likely the server-side ETR) decides to "glean" * Either side (more likely the server-side ETR) decides to "glean"
the RLOCs. For example, if the server-side ETR gleans RLOCs, then the RLOCs. For example, if the server-side ETR gleans RLOCs, then
the client-side ITR gives the client-side ITR responsibility for the client-side ITR gives the server-side ETR responsibility for
bidirectional RLOC reachability and preferability. Server-side bidirectional RLOC reachability and preferability. Server-side
ETR gleaning of the client-side ITR RLOC is done by caching the ETR gleaning of the client-side ITR RLOC is done by caching the
inner-header source EID and the outer-header source RLOC of inner-header source EID and the outer-header source RLOC of
received packets. The client-side ITR controls how traffic is received packets. The client-side ITR controls how traffic is
returned and can alternate using an outer-header source RLOC, returned and can, as an alternative, use an outer-header source
which then can be added to the list the server-side ETR uses to RLOC, which then can be added to the list the server-side ETR uses
return traffic. Since no Priority or Weights are provided using to return traffic. Since no Priority or Weights are provided
this method, the server-side ETR MUST assume that each client-side using this method, the server-side ETR MUST assume that each
ITR RLOC uses the same best Priority with a Weight of zero. In client-side ITR RLOC uses the same best Priority with a Weight of
addition, since EID-Prefix encoding cannot be conveyed in data zero. In addition, since EID-Prefix encoding cannot be conveyed
packets, the EID-to-RLOC Cache on Tunnel Routers can grow to be in data packets, the EID-to-RLOC Map-Cache on Tunnel Routers can
very large. Gleaning has several important considerations. A grow very large. Gleaning has several important considerations.
"gleaned" Map-Cache entry is only stored and used for a A "gleaned" Map-Cache entry is only stored and used for a
RECOMMENDED period of 3 seconds, pending verification. RECOMMENDED period of 3 seconds, pending verification.
Verification MUST be performed by sending a Map-Request to the Verification MUST be performed by sending a Map-Request to the
source EID (the inner-header IP source address) of the received source EID (the inner-header IP source address) of the received
encapsulated packet. A reply to this "verifying Map-Request" is encapsulated packet. A reply to this "verifying Map-Request" is
used to fully populate the Map-Cache entry for the "gleaned" EID used to fully populate the Map-Cache entry for the "gleaned" EID
and is stored and used for the time indicated from the 'TTL' field and is stored and used for the time indicated in the 'Time to
of a received Map-Reply. When a verified Map- Cache entry is Live' field of a received Map-Reply. When a verified Map-Cache
stored, data gleaning no longer occurs for subsequent packets that entry is stored, data gleaning no longer occurs for subsequent
have a source EID that matches the EID-Prefix of the verified packets that have a source EID that matches the EID-Prefix of the
entry. This "gleaning" mechanism MUST NOT be used over the public verified entry. This "gleaning" mechanism MUST NOT be used over
Internet and SHOULD only be used in trusted and closed the public Internet and SHOULD only be used in trusted and closed
deployments. Refer to Section 16 for security issues regarding deployments. Refer to Section 16 for security issues regarding
this mechanism. this mechanism.
RLOCs that appear in EID-to-RLOC Map-Reply messages are assumed to be RLOCs that appear in EID-to-RLOC Map-Reply messages are assumed to be
reachable when the R-bit [I-D.ietf-lisp-rfc6833bis] for the Locator reachable when the R-bit [RFC9301] for the Locator record is set to
record is set to 1. When the R-bit is set to 0, an ITR or PITR MUST 1. When the R-bit is set to 0, an ITR or PITR MUST NOT encapsulate
NOT encapsulate to the RLOC. Neither the information contained in a to the RLOC. Neither the information contained in a Map-Reply nor
Map-Reply nor that stored in the mapping database system provides that stored in the mapping database system provides reachability
reachability information for RLOCs. Note that reachability is not information for RLOCs. Note that reachability is not part of the
part of the mapping system and is determined using one or more of the Mapping System and is determined using one or more of the RLOC
Routing Locator reachability algorithms described in the next reachability algorithms described in the next section.
section.
10. Routing Locator Reachability 10. Routing Locator Reachability
Several Data-Plane mechanisms for determining RLOC reachability are Several data plane mechanisms for determining RLOC reachability are
currently defined. Please note that additional Control-Plane based currently defined. Please note that additional reachability
reachability mechanisms are defined in [I-D.ietf-lisp-rfc6833bis]. mechanisms based on the control plane are defined in [RFC9301].
1. An ETR MAY examine the Locator-Status-Bits in the LISP header of 1. An ETR MAY examine the Locator-Status-Bits in the LISP header of
an encapsulated data packet received from an ITR. If the ETR is an encapsulated data packet received from an ITR. If the ETR is
also acting as an ITR and has traffic to return to the original also acting as an ITR and has traffic to return to the original
ITR site, it can use this status information to help select an ITR site, it can use this status information to help select an
RLOC. RLOC.
2. When an ETR receives an encapsulated packet from an ITR, the 2. When an ETR receives an encapsulated packet from an ITR, the
source RLOC from the outer header of the packet is likely to be source RLOC from the outer header of the packet is likely to be
reachable. Please note that in some scenarios the RLOC from the reachable. Please note that in some scenarios the RLOC from the
outer header can be an spoofable field. outer header can be a spoofable field.
3. An ITR/ETR pair can use the 'Echo-Noncing' Locator reachability 3. An ITR/ETR pair can use the Echo-Noncing Locator reachability
algorithms described in this section. algorithms described in this section.
When determining Locator up/down reachability by examining the When determining Locator up/down reachability by examining the
Locator-Status-Bits from the LISP-encapsulated data packet, an ETR Locator-Status-Bits from the LISP-encapsulated data packet, an ETR
will receive up-to-date status from an encapsulating ITR about will receive an up-to-date status from an encapsulating ITR about
reachability for all ETRs at the site. CE-based ITRs at the source reachability for all ETRs at the site. CE-based ITRs at the source
site can determine reachability relative to each other using the site site can determine reachability relative to each other using the site
IGP as follows: IGP as follows:
o Under normal circumstances, each ITR will advertise a default * Under normal circumstances, each ITR will advertise a default
route into the site IGP. route into the site IGP.
o If an ITR fails or if the upstream link to its PE fails, its * If an ITR fails or if the upstream link to its Provider Edge
default route will either time out or be withdrawn. fails, its default route will either time out or be withdrawn.
Each ITR can thus observe the presence or lack of a default route Each ITR can thus observe the presence or lack of a default route
originated by the others to determine the Locator-Status-Bits it sets originated by the others to determine the Locator-Status-Bits it sets
for them. for them.
When ITRs at the site are not deployed in CE routers, the IGP can When ITRs at the site are not deployed in CE routers, the IGP can
still be used to determine the reachability of Locators, provided still be used to determine the reachability of Locators, provided
they are injected into the IGP. This is typically done when a /32 they are injected into the IGP. This is typically done when a /32
address is configured on a loopback interface. address is configured on a loopback interface.
RLOCs listed in a Map-Reply are numbered with ordinals 0 to n-1. The RLOCs listed in a Map-Reply are numbered with ordinals 0 to n-1. The
Locator-Status-Bits in a LISP-encapsulated packet are numbered from 0 Locator-Status-Bits in a LISP-encapsulated packet are numbered from 0
to n-1 starting with the least significant bit. For example, if an to n-1 starting with the least significant bit. For example, if an
RLOC listed in the 3rd position of the Map-Reply goes down (ordinal RLOC listed in the 3rd position of the Map-Reply goes down (ordinal
value 2), then all ITRs at the site will clear the 3rd least value 2), then all ITRs at the site will clear the 3rd least
significant bit (xxxx x0xx) of the 'Locator-Status-Bits' field for significant bit (xxxx x0xx) of the 'Locator-Status-Bits' field for
the packets they encapsulate. the packets they encapsulate.
When an xTR decides to use 'Locator-Status-Bits' to affect When an xTR decides to use Locator-Status-Bits to affect reachability
reachability information, it acts as follows: ETRs decapsulating a information, it acts as follows: ETRs decapsulating a packet will
packet will check for any change in the 'Locator-Status-Bits' field. check for any change in the 'Locator-Status-Bits' field. When a bit
When a bit goes from 1 to 0, the ETR, if acting also as an ITR, will goes from 1 to 0, the ETR, if also acting as an ITR, will refrain
refrain from encapsulating packets to an RLOC that is indicated as from encapsulating packets to an RLOC that is indicated as down. It
down. It will only resume using that RLOC if the corresponding will only resume using that RLOC if the corresponding Locator-Status-
Locator-Status-Bit returns to a value of 1. Locator-Status-Bits are Bit returns to a value of 1. Locator-Status-Bits are associated with
associated with a Locator-Set per EID-Prefix. Therefore, when a a Locator-Set per EID-Prefix. Therefore, when a Locator becomes
Locator becomes unreachable, the Locator-Status-Bit that corresponds unreachable, the Locator-Status-Bit that corresponds to that
to that Locator's position in the list returned by the last Map-Reply Locator's position in the list returned by the last Map-Reply will be
will be set to zero for that particular EID-Prefix. set to zero for that particular EID-Prefix.
Locator-Status-Bits MUST NOT be used over the public Internet and Locator-Status-Bits MUST NOT be used over the public Internet and
SHOULD only be used in trusted and closed deployments. In addition SHOULD only be used in trusted and closed deployments. In addition,
Locator-Status-Bits SHOULD be coupled with Map-Versioning Locator-Status-Bits SHOULD be coupled with Map-Versioning [RFC9302]
(Section 13.2) to prevent race conditions where Locator-Status-Bits to prevent race conditions where Locator-Status-Bits are interpreted
are interpreted as referring to different RLOCs than intended. Refer as referring to different RLOCs than intended. Refer to Section 16
to Section 16 for security issues regarding this mechanism. for security issues regarding this mechanism.
If an ITR encapsulates a packet to an ETR and the packet is received If an ITR encapsulates a packet to an ETR and the packet is received
and decapsulated by the ETR, it is implied but not confirmed by the and decapsulated by the ETR, it is implied, but not confirmed by the
ITR that the ETR's RLOC is reachable. In most cases, the ETR can ITR, that the ETR's RLOC is reachable. In most cases, the ETR can
also reach the ITR but cannot assume this to be true, due to the also reach the ITR but cannot assume this to be true, due to the
possibility of path asymmetry. In the presence of unidirectional possibility of path asymmetry. In the presence of unidirectional
traffic flow from an ITR to an ETR, the ITR SHOULD NOT use the lack traffic flow from an ITR to an ETR, the ITR SHOULD NOT use the lack
of return traffic as an indication that the ETR is unreachable. of return traffic as an indication that the ETR is unreachable.
Instead, it MUST use an alternate mechanism to determine Instead, it MUST use an alternate mechanism to determine
reachability. reachability.
The security considerations of Section 16 related to data-plane The security considerations of Section 16 related to data plane
reachability applies to the data-plane RLOC reachability mechanisms reachability apply to the data plane RLOC reachability mechanisms
described in this section. described in this section.
10.1. Echo Nonce Algorithm 10.1. Echo-Nonce Algorithm
When data flows bidirectionally between Locators from different When data flows bidirectionally between Locators from different
sites, a Data-Plane mechanism called "nonce echoing" can be used to sites, a data plane mechanism called "nonce echoing" can be used to
determine reachability between an ITR and ETR. When an ITR wants to determine reachability between an ITR and ETR. When an ITR wants to
solicit a nonce echo, it sets the N- and E-bits and places a 24-bit solicit a nonce echo, it sets the N- and E-bits and places a 24-bit
nonce [RFC4086] in the LISP header of the next encapsulated data nonce [RFC4086] in the LISP header of the next encapsulated data
packet. packet.
When this packet is received by the ETR, the encapsulated packet is When this packet is received by the ETR, the encapsulated packet is
forwarded as normal. When the ETR is an xTR (co-located as an ITR), forwarded as normal. When the ETR is an xTR (co-located as an ITR),
it then sends a data packet to the ITR (when it is an xTR co-located it then sends a data packet to the ITR (when it is an xTR co-located
as an ETR), it includes the nonce received earlier with the N-bit set as an ETR) and includes the nonce received earlier with the N-bit set
and E-bit cleared. The ITR sees this "echoed nonce" and knows that and E-bit cleared. The ITR sees this "echoed nonce" and knows that
the path to and from the ETR is up. the path to and from the ETR is up.
The ITR will set the E-bit and N-bit for every packet it sends while The ITR will set the E-bit and N-bit for every packet it sends while
in the echo-nonce-request state. The time the ITR waits to process in the Echo-Nonce-request state. The time the ITR waits to process
the echoed nonce before it determines the path is unreachable is the echoed nonce before it determines that the path is unreachable is
variable and is a choice left for the implementation. variable and is a choice left for the implementation.
If the ITR is receiving packets from the ETR but does not see the If the ITR is receiving packets from the ETR but does not see the
nonce echoed while being in the echo-nonce-request state, then the nonce echoed while being in the Echo-Nonce-request state, then the
path to the ETR is unreachable. This decision MAY be overridden by path to the ETR is unreachable. This decision MAY be overridden by
other Locator reachability algorithms. Once the ITR determines that other Locator reachability algorithms. Once the ITR determines that
the path to the ETR is down, it can switch to another Locator for the path to the ETR is down, it can switch to another Locator for
that EID-Prefix. that EID-Prefix.
Note that "ITR" and "ETR" are relative terms here. Both devices MUST Note that "ITR" and "ETR" are relative terms here. Both devices MUST
be implementing both ITR and ETR functionality for the echo nonce be implementing both ITR and ETR functionality for the Echo-Nonce
mechanism to operate. mechanism to operate.
The ITR and ETR MAY both go into the echo-nonce-request state at the The ITR and ETR MAY both go into the Echo-Nonce-request state at the
same time. The number of packets sent or the time during which echo same time. The number of packets sent or the time during which Echo-
nonce requests are sent is an implementation-specific setting. In Nonce request packets are sent is an implementation-specific setting.
this case, an xTR receiving the echo-nonce-request packets will In this case, an xTR receiving the Echo-Nonce request packets will
suspend the echo-nonce-request state and setup a 'echo-nonce-request- suspend the Echo-Nonce state and set up an 'Echo-Nonce-request-state'
state' timer. After the 'echo-nonce-request-state' timer expires it timer. After the 'Echo-Nonce-request-state' timer expires, it will
will resume the echo-nonce-request state. resume the Echo-Nonce state.
This mechanism does not completely solve the forward path This mechanism does not completely solve the forward path
reachability problem, as traffic may be unidirectional. That is, the reachability problem, as traffic may be unidirectional. That is, the
ETR receiving traffic at a site MAY not be the same device as an ITR ETR receiving traffic at a site MAY not be the same device as an ITR
that transmits traffic from that site, or the site-to-site traffic is that transmits traffic from that site, or the site-to-site traffic is
unidirectional so there is no ITR returning traffic. unidirectional so there is no ITR returning traffic.
The echo-nonce algorithm is bilateral. That is, if one side sets the The Echo-Nonce algorithm is bilateral. That is, if one side sets the
E-bit and the other side is not enabled for echo-noncing, then the E-bit and the other side is not enabled for Echo-Noncing, then the
echoing of the nonce does not occur and the requesting side may echoing of the nonce does not occur and the requesting side may
erroneously consider the Locator unreachable. An ITR SHOULD set the erroneously consider the Locator unreachable. An ITR SHOULD set the
E-bit in an encapsulated data packet when it knows the ETR is enabled E-bit in an encapsulated data packet when it knows the ETR is enabled
for echo-noncing. This is conveyed by the E-bit in the Map-Reply for Echo-Noncing. This is conveyed by the E-bit in the Map-Reply
message. message.
Many implementations default to not advertising they are echo-nonce Many implementations default to not advertising that they are Echo-
capable in Map-Reply messages and so RLOC-probing tends to be used Nonce capable in Map-Reply messages, and so RLOC-Probing tends to be
for RLOC reachability. used for RLOC reachability.
The echo-nonce mechanism MUST NOT be used over the public Internet The Echo-Nonce mechanism MUST NOT be used over the public Internet
and MUST only be used in trusted and closed deployments. Refer to and MUST only be used in trusted and closed deployments. Refer to
Section 16 for security issues regarding this mechanism. Section 16 for security issues regarding this mechanism.
11. EID Reachability within a LISP Site 11. EID Reachability within a LISP Site
A site MAY be multihomed using two or more ETRs. The hosts and A site MAY be multihomed using two or more ETRs. The hosts and
infrastructure within a site will be addressed using one or more EID- infrastructure within a site will be addressed using one or more EID-
Prefixes that are mapped to the RLOCs of the relevant ETRs in the Prefixes that are mapped to the RLOCs of the relevant ETRs in the
mapping system. One possible failure mode is for an ETR to lose Mapping System. One possible failure mode is for an ETR to lose
reachability to one or more of the EID-Prefixes within its own site. reachability to one or more of the EID-Prefixes within its own site.
When this occurs when the ETR sends Map-Replies, it can clear the When this occurs when the ETR sends Map-Replies, it can clear the
R-bit associated with its own Locator. And when the ETR is also an R-bit associated with its own Locator. And when the ETR is also an
ITR, it can clear its Locator-Status-Bit in the encapsulation data ITR, it can clear its Locator-Status-Bit in the encapsulation data
header. header.
It is recognized that there are no simple solutions to the site It is recognized that there are no simple solutions to the site
partitioning problem because it is hard to know which part of the partitioning problem because it is hard to know which part of the
EID-Prefix range is partitioned and which Locators can reach any sub- EID-Prefix range is partitioned and which Locators can reach any sub-
ranges of the EID-Prefixes. Note that this is not a new problem ranges of the EID-Prefixes. Note that this is not a new problem
introduced by the LISP architecture. The problem exists today when a introduced by the LISP architecture. At the time of this writing,
multihomed site uses BGP to advertise its reachability upstream. this problem exists when a multihomed site uses BGP to advertise its
reachability upstream.
12. Routing Locator Hashing 12. Routing Locator Hashing
When an ETR provides an EID-to-RLOC mapping in a Map-Reply message When an ETR provides an EID-to-RLOC mapping in a Map-Reply message
that is stored in the Map-Cache of a requesting ITR, the Locator-Set that is stored in the Map-Cache of a requesting ITR, the Locator-Set
for the EID-Prefix MAY contain different Priority and Weight values for the EID-Prefix MAY contain different Priority and Weight values
for each locator address. When more than one best Priority Locator for each Routing Locator Address. When more than one best Priority
exists, the ITR can decide how to load-share traffic against the Locator exists, the ITR can decide how to load-share traffic against
corresponding Locators. the corresponding Locators.
The following hash algorithm MAY be used by an ITR to select a The following hash algorithm MAY be used by an ITR to select a
Locator for a packet destined to an EID for the EID-to-RLOC mapping: Locator for a packet destined to an EID for the EID-to-RLOC mapping:
1. Either a source and destination address hash or the traditional 1. Either a source and destination address hash or the commonly used
5-tuple hash can be used. The traditional 5-tuple hash includes 5-tuple hash can be used. The commonly used 5-tuple hash
the source and destination addresses; source and destination TCP, includes the source and destination addresses; source and
UDP, or Stream Control Transmission Protocol (SCTP) port numbers; destination TCP, UDP, or Stream Control Transmission Protocol
and the IP protocol number field or IPv6 next-protocol fields of (SCTP) port numbers; and the IP protocol number field or IPv6
a packet that a host originates from within a LISP site. When a next-protocol fields of a packet that a host originates from
packet is not a TCP, UDP, or SCTP packet, the source and within a LISP site. When a packet is not a TCP, UDP, or SCTP
destination addresses only from the header are used to compute packet, the source and destination addresses only from the header
the hash. are used to compute the hash.
2. Take the hash value and divide it by the number of Locators 2. Take the hash value and divide it by the number of Locators
stored in the Locator-Set for the EID-to-RLOC mapping. stored in the Locator-Set for the EID-to-RLOC mapping.
3. The remainder will yield a value of 0 to "number of Locators 3. The remainder will yield a value of 0 to "number of Locators
minus 1". Use the remainder to select the Locator in the minus 1". Use the remainder to select the Locator in the
Locator-Set. Locator-Set.
The specific hash algorithm the ITR uses for load-sharing is out of The specific hash algorithm the ITR uses for load-sharing is out of
scope for this document and does not prevent interoperability. scope for this document and does not prevent interoperability.
The Source port SHOULD be the same for all packets belonging to the The source port SHOULD be the same for all packets belonging to the
same flow. Also note that when a packet is LISP encapsulated, the same flow. Also note that when a packet is LISP encapsulated, the
source port number in the outer UDP header needs to be set. source port number in the outer UDP header needs to be set.
Selecting a hashed value allows core routers that are attached to Selecting a hashed value allows core routers that are attached to
Link Aggregation Groups (LAGs) to load-split the encapsulated packets Link Aggregation Groups (LAGs) to load-split the encapsulated packets
across member links of such LAGs. Otherwise, core routers would see across member links of such LAGs. Otherwise, core routers would see
a single flow, since packets have a source address of the ITR, for a single flow, since packets have a source address of the ITR, for
packets that are originated by different EIDs at the source site. A packets that are originated by different EIDs at the source site. A
suggested setting for the source port number computed by an ITR is a suggested setting for the source port number computed by an ITR is a
5-tuple hash function on the inner header, as described above. The 5-tuple hash function on the inner header, as described above. The
source port SHOULD be the same for all packets belonging to the same source port SHOULD be the same for all packets belonging to the same
flow. flow.
Many core router implementations use a 5-tuple hash to decide how to Many core router implementations use a 5-tuple hash to decide how to
balance packet load across members of a LAG. The 5-tuple hash balance packet load across members of a LAG. The 5-tuple hash
includes the source and destination addresses of the packet and the includes the source and destination addresses of the packet and the
source and destination ports when the protocol number in the packet source and destination ports when the protocol number in the packet
is TCP or UDP. For this reason, UDP encoding is used for LISP is TCP or UDP. For this reason, UDP encoding is used for LISP
encapsulation. In this scenario, when the outer header is IPv6, the encapsulation. In this scenario, when the outer header is IPv6, the
flow label MAY also be set following the procedures specified in flow label MAY also be set following the procedures specified in
[RFC6438]. When the inner header is IPv6 then the flow label is not [RFC6438]. When the inner header is IPv6 and the flow label is not
zero, it MAY be used to compute the hash. zero, it MAY be used to compute the hash.
13. Changing the Contents of EID-to-RLOC Mappings 13. Changing the Contents of EID-to-RLOC Mappings
Since the LISP architecture uses a caching scheme to retrieve and Since the LISP architecture uses a caching scheme to retrieve and
store EID-to-RLOC mappings, the only way an ITR can get a more up-to- store EID-to-RLOC mappings, the only way an ITR can get a more up-to-
date mapping is to re-request the mapping. However, the ITRs do not date mapping is to re-request the mapping. However, the ITRs do not
know when the mappings change, and the ETRs do not keep track of know when the mappings change, and the ETRs do not keep track of
which ITRs requested its mappings. For scalability reasons, it is which ITRs requested their mappings. For scalability reasons, it is
desirable to maintain this approach but need to provide a way for desirable to maintain this approach, but implementors need to provide
ETRs to change their mappings and inform the sites that are currently a way for ETRs to change their mappings and inform the sites that are
communicating with the ETR site using such mappings. currently communicating with the ETR site using such mappings.
This section defines two Data-Plane mechanism for updating EID-to- This section defines two data plane mechanism for updating EID-to-
RLOC mappings. Additionally, the Solicit-Map Request (SMR) Control- RLOC mappings. Additionally, the Solicit-Map-Request (SMR) control
Plane updating mechanism is specified in [I-D.ietf-lisp-rfc6833bis]. plane updating mechanism is specified in [RFC9301].
13.1. Locator-Status-Bits 13.1. Locator-Status-Bits
Locator-Status-Bits (LSB) can also be used to keep track of the Locator-Status-Bits (LSBs) can also be used to keep track of the
Locator status (up or down) when EID-to-RLOC mappings are changing. Locator status (up or down) when EID-to-RLOC mappings are changing.
When LSB are used in a LISP deployment, all LISP tunnel routers MUST When LSBs are used in a LISP deployment, all LISP Tunnel Routers MUST
implement both ITR and ETR capabilities (therefore all tunnel routers implement both ITR and ETR capabilities (therefore, all Tunnel
are effectively xTRs). In this section the term "source xTR" is used Routers are effectively xTRs). In this section, the term "source
to refer to the xTR setting the LSB and "destination xTR" is used to xTR" is used to refer to the xTR setting the LSB and "destination
refer to the xTR receiving the LSB. The procedure is as follows: xTR" is used to refer to the xTR receiving the LSB. The procedure is
as follows:
First, when a Locator record is added or removed from the Locator- 1. When a Locator record is added or removed from the Locator-Set,
Set, the source xTR will signal this by sending a Solicit-Map Request the source xTR will signal this by sending an SMR control plane
(SMR) Control-Plane message [I-D.ietf-lisp-rfc6833bis] to the message [RFC9301] to the destination xTR. At this point, the
destination xTR. At this point the source xTR MUST NOT use LSB source xTR MUST NOT use the LSB field, when the L-bit is 0, since
(L-bit = 0) since the destination xTR site has outdated information. the destination xTR site has outdated information. The source
The source xTR will setup a 'use-LSB' timer. xTR will set up a 'use-LSB' timer.
Second and as defined in [I-D.ietf-lisp-rfc6833bis], upon reception 2. As defined in [RFC9301], upon reception of the SMR message, the
of the SMR message the destination xTR will retrieve the updated EID- destination xTR will retrieve the updated EID-to-RLOC mappings by
to-RLOC mappings by sending a Map-Request. sending a Map-Request.
And third, when the 'use-LSB' timer expires, the source xTR can use 3. When the 'use-LSB' timer expires, the source xTR can use the LSB
again LSB with the destination xTR to signal the Locator status (up again with the destination xTR to signal the Locator status (up
or down). The specific value for the 'use-LSB' timer depends on the or down). The specific value for the 'use-LSB' timer depends on
LISP deployment, the 'use-LSB' timer needs to be large enough for the the LISP deployment; the 'use-LSB' timer needs to be large enough
destination xTR to retreive the updated EID-to-RLOC mappings. A for the destination xTR to retrieve the updated EID-to-RLOC
RECOMMENDED value for the 'use-LSB' timer is 5 minutes. mappings. A RECOMMENDED value for the 'use-LSB' timer is 5
minutes.
13.2. Database Map-Versioning 13.2. Database Map-Versioning
When there is unidirectional packet flow between an ITR and ETR, and When there is unidirectional packet flow between an ITR and ETR, and
the EID-to-RLOC mappings change on the ETR, it needs to inform the the EID-to-RLOC mappings change on the ETR, it needs to inform the
ITR so encapsulation to a removed Locator can stop and can instead be ITR so encapsulation to a removed Locator can stop and can instead be
started to a new Locator in the Locator-Set. started to a new Locator in the Locator-Set.
An ETR, when it sends Map-Reply messages, conveys its own Map-Version An ETR can send Map-Reply messages carrying a Map-Version Number
Number. This is known as the Destination Map-Version Number. ITRs [RFC9302] in an EID-Record. This is known as the Destination Map-
include the Destination Map-Version Number in packets they Version Number. ITRs include the Destination Map-Version Number in
encapsulate to the site. When an ETR decapsulates a packet and packets they encapsulate to the site.
detects that the Destination Map-Version Number is less than the
current version for its mapping, the SMR procedure described in
[I-D.ietf-lisp-rfc6833bis] occurs.
An ITR, when it encapsulates packets to ETRs, can convey its own Map- An ITR, when it encapsulates packets to ETRs, can convey its own Map-
Version Number. This is known as the Source Map-Version Number. Version Number. This is known as the Source Map-Version Number.
When an ETR decapsulates a packet and detects that the Source Map-
Version Number is greater than the last Map-Version Number sent in a
Map-Reply from the ITR's site, the ETR will send a Map-Request to one
of the ETRs for the source site.
A Map-Version Number is used as a sequence number per EID-Prefix, so
values that are greater are considered to be more recent. A value of
0 for the Source Map-Version Number or the Destination Map-Version
Number conveys no versioning information, and an ITR does no
comparison with previously received Map-Version Numbers.
A Map-Version Number can be included in Map-Register messages as
well. This is a good way for the Map-Server to assure that all ETRs
for a site registering to it will be synchronized according to Map-
Version Number.
Map-Version requires that ETRs within the LISP site are synchronized
with respect to the Map-Version Number, EID-prefix and the set and
status (up/down) of the RLOCs. The use of Map-Versioning without
proper synchronization may cause traffic disruption. The
synchronization protocol is out-of-the-scope of this document, but
MUST keep ETRs synchronized within a 1 minute window.
Map-Versioning MUST NOT be used over the public Internet and SHOULD When presented in EID-Records of Map-Register messages [RFC9301], a
only be used in trusted and closed deployments. Refer to Section 16 Map-Version Number is a good way for the Map-Server [RFC9301] to
for security issues regarding this mechanism. assure that all ETRs for a site registering to it are synchronized
according to the Map-Version Number.
See [I-D.ietf-lisp-6834bis] for a more detailed analysis and See [RFC9302] for a more detailed analysis and description of
description of Database Map-Versioning. Database Map-Versioning.
14. Multicast Considerations 14. Multicast Considerations
A multicast group address, as defined in the original Internet A multicast group address, as defined in the original Internet
architecture, is an identifier of a grouping of topologically architecture, is an identifier of a grouping of topologically
independent receiver host locations. The address encoding itself independent receiver host locations. The address encoding itself
does not determine the location of the receiver(s). The multicast does not determine the location of the receiver(s). The multicast
routing protocol, and the network-based state the protocol creates, routing protocol and the network-based state the protocol creates
determine where the receivers are located. determine where the receivers are located.
In the context of LISP, a multicast group address is both an EID and In the context of LISP, a multicast group address is both an EID and
a Routing Locator. Therefore, no specific semantic or action needs an RLOC. Therefore, no specific semantic or action needs to be taken
to be taken for a destination address, as it would appear in an IP for a destination address, as it would appear in an IP header.
header. Therefore, a group address that appears in an inner IP Therefore, a group address that appears in an inner IP header built
header built by a source host will be used as the destination EID. by a source host will be used as the destination EID. The outer IP
The outer IP header (the destination Routing Locator address), header (the destination RLOC address), prepended by a LISP router,
prepended by a LISP router, can use the same group address as the can use the same group address as the destination RLOC, use a
destination Routing Locator, use a multicast or unicast Routing multicast or unicast RLOC obtained from a Mapping System lookup, or
Locator obtained from a Mapping System lookup, or use other means to use other means to determine the group address mapping.
determine the group address mapping.
With respect to the source Routing Locator address, the ITR prepends With respect to the source RLOC address, the ITR prepends its own IP
its own IP address as the source address of the outer IP header, just address as the source address of the outer IP header, just like it
like it would if the destination EID was a unicast address. This would if the destination EID was a unicast address. This source RLOC
source Routing Locator address, like any other Routing Locator address, like any other RLOC address, MUST be routable on the
address, MUST be routable on the underlay. underlay.
There are two approaches for LISP-Multicast, one that uses native There are two approaches for LISP-Multicast [RFC6831]: one that uses
multicast routing in the underlay with no support from the Mapping native multicast routing in the underlay with no support from the
System and the other that uses only unicast routing in the underlay Mapping System and another that uses only unicast routing in the
with support from the Mapping System. See [RFC6831] and [RFC8378], underlay with support from the Mapping System. See [RFC6831] and
respectively, for details. Details for LISP-Multicast and [RFC8378], respectively, for details. Details for LISP-Multicast and
interworking with non-LISP sites are described in [RFC6831] and interworking with non-LISP sites are described in [RFC6831] and
[RFC6832]. [RFC6832], respectively.
15. Router Performance Considerations 15. Router Performance Considerations
LISP is designed to be very "hardware-based forwarding friendly". A LISP is designed to be very "hardware based and forwarding friendly".
few implementation techniques can be used to incrementally implement A few implementation techniques can be used to incrementally
LISP: implement LISP:
o When a tunnel-encapsulated packet is received by an ETR, the outer * When a tunnel-encapsulated packet is received by an ETR, the outer
destination address may not be the address of the router. This destination address may not be the address of the router. This
makes it challenging for the control plane to get packets from the makes it challenging for the control plane to get packets from the
hardware. This may be mitigated by creating special Forwarding hardware. This may be mitigated by creating special Forwarding
Information Base (FIB) entries for the EID-Prefixes of EIDs served Information Base (FIB) entries for the EID-Prefixes of EIDs served
by the ETR (those for which the router provides an RLOC by the ETR (those for which the router provides an RLOC
translation). These FIB entries are marked with a flag indicating translation). These FIB entries are marked with a flag indicating
that Control-Plane processing SHOULD be performed. The forwarding that control plane processing SHOULD be performed. The forwarding
logic of testing for particular IP protocol number values is not logic of testing for particular IP protocol number values is not
necessary. There are a few proven cases where no changes to necessary. There are a few proven cases where no changes to
existing deployed hardware were needed to support the LISP Data- existing deployed hardware were needed to support the LISP data
Plane. plane.
o On an ITR, prepending a new IP header consists of adding more * On an ITR, prepending a new IP header consists of adding more
octets to a MAC rewrite string and prepending the string as part octets to a Message Authentication Code (MAC) rewrite string and
of the outgoing encapsulation procedure. Routers that support prepending the string as part of the outgoing encapsulation
Generic Routing Encapsulation (GRE) tunneling [RFC2784] or 6to4 procedure. Routers that support Generic Routing Encapsulation
tunneling [RFC3056] may already support this action. (GRE) tunneling [RFC2784] or 6to4 tunneling [RFC3056] may already
support this action.
o A packet's source address or interface the packet was received on * A packet's source address or the interface on which the packet was
can be used to select VRF (Virtual Routing/Forwarding). The VRF's received can be used to select Virtual Routing and Forwarding
routing table can be used to find EID-to-RLOC mappings. (VRF). The VRF system's routing table can be used to find EID-to-
RLOC mappings.
For performance issues related to Map-Cache management, see For performance issues related to Map-Cache management, see
Section 16. Section 16.
16. Security Considerations 16. Security Considerations
In what follows we highlight security considerations that apply when In what follows, we highlight security considerations that apply when
LISP is deployed in environments such as those specified in LISP is deployed in environments such as those specified in
Section 1.1. Section 1.1.
The optional mechanisms of gleaning is offered to directly obtain a The optional gleaning mechanism is offered to directly obtain a
mapping from the LISP encapsulated packets. Specifically, an xTR can mapping from the LISP-encapsulated packets. Specifically, an xTR can
learn the EID-to-RLOC mapping by inspecting the source RLOC and learn the EID-to-RLOC mapping by inspecting the source RLOC and
source EID of an encapsulated packet, and insert this new mapping source EID of an encapsulated packet and insert this new mapping into
into its Map-Cache. An off-path attacker can spoof the source EID its Map-Cache. An off-path attacker can spoof the source EID address
address to divert the traffic sent to the victim's spoofed EID. If to divert the traffic sent to the victim's spoofed EID. If the
the attacker spoofs the source RLOC, it can mount a DoS attack by attacker spoofs the source RLOC, it can mount a DoS attack by
redirecting traffic to the spoofed victim's RLOC, potentially redirecting traffic to the spoofed victim's RLOC, potentially
overloading it. overloading it.
The LISP Data-Plane defines several mechanisms to monitor RLOC Data- The LISP data plane defines several mechanisms to monitor RLOC data
Plane reachability, in this context Locator-Status Bits, Nonce- plane reachability; in this context, Locator-Status-Bits, nonce-
Present and Echo-Nonce bits of the LISP encapsulation header can be present bits, and Echo-Nonce bits of the LISP encapsulation header
manipulated by an attacker to mount a DoS attack. An off-path can be manipulated by an attacker to mount a DoS attack. An off-path
attacker able to spoof the RLOC and/or nonce of a victim's xTR can attacker able to spoof the RLOC and/or nonce of a victim's xTR can
manipulate such mechanisms to declare false information about the manipulate such mechanisms to declare false information about the
RLOC's reachability status. RLOC's reachability status.
For example of such attacks, an off-path attacker can exploit the An example of such attacks is when an off-path attacker can exploit
echo-nonce mechanism by sending data packets to an ITR with a random the Echo-Nonce mechanism by sending data packets to an ITR with a
nonce from an ETR's spoofed RLOC. Note the attacker must guess a random nonce from an ETR's spoofed RLOC. Note that the attacker only
valid nonce the ITR is requesting to be echoed within a small window has a small window of time within which to guess a valid nonce that
of time. The goal is to convince the ITR that the ETR's RLOC is the ITR is requesting to be echoed. The goal is to convince the ITR
reachable even when it may not be reachable. If the attack is that the ETR's RLOC is reachable even when it may not be reachable.
successful, the ITR believes the wrong reachability status of the If the attack is successful, the ITR believes the wrong reachability
ETR's RLOC until RLOC-probing detects the correct status. This time status of the ETR's RLOC until RLOC-Probing detects the correct
frame is on the order of 10s of seconds. This specific attack can be status. This time frame is on the order of tens of seconds. This
mitigated by preventing RLOC spoofing in the network by deploying specific attack can be mitigated by preventing RLOC spoofing in the
uRPF BCP 38 [RFC2827]. In addition and in order to exploit this network by deploying Unicast Reverse Path Forwarding (uRPF) per BCP
vulnerability, the off-path attacker must send echo-nonce packets at 84 [RFC8704]. In order to exploit this vulnerability, the off-path
high rate. If the nonces have never been requested by the ITR, it attacker must also send Echo-Nonce packets at a high rate. If the
can protect itself from erroneous reachability attacks. nonces have never been requested by the ITR, it can protect itself
from erroneous reachability attacks.
A LISP-specific uRPF check is also possible. When decapsulating, an A LISP-specific uRPF check is also possible. When decapsulating, an
ETR can check that the source EID and RLOC are valid EID-to-RLOC ETR can check that the source EID and RLOC are valid EID-to-RLOC
mappings by checking the Mapping System. mappings by checking the Mapping System.
Map-Versioning is a Data-Plane mechanism used to signal a peering xTR Map-Versioning is a data plane mechanism used to signal to a peering
that a local EID-to-RLOC mapping has been updated, so that the xTR that a local EID-to-RLOC mapping has been updated so that the
peering xTR uses LISP Control-Plane signaling message to retrieve a peering xTR uses a LISP control plane signaling message to retrieve a
fresh mapping. This can be used by an attacker to forge the map- fresh mapping. This can be used by an attacker to forge the 'Map-
versioning field of a LISP encapsulated header and force an excessive Version' field of a LISP-encapsulated header and force an excessive
amount of signaling between xTRs that may overload them. amount of signaling between xTRs that may overload them. Further
security considerations on Map-Versioning can be found in [RFC9302].
Locator-Status-Bits, echo-nonce and map-versioning MUST NOT be used Locator-Status-Bits, the Echo-Nonce mechanism, and Map-Versioning
over the public Internet and SHOULD only be used in trusted and MUST NOT be used over the public Internet and SHOULD only be used in
closed deployments. In addition Locator-Status-Bits SHOULD be trusted and closed deployments. In addition, Locator-Status-Bits
coupled with map-versioning to prevent race conditions where Locator- SHOULD be coupled with Map-Versioning to prevent race conditions
Status-Bits are interpreted as referring to different RLOCs than where Locator-Status-Bits are interpreted as referring to different
intended. RLOCs than intended.
LISP implementations and deployments which permit outer header LISP implementations and deployments that permit outer header
fragments of IPv6 LISP encapsulated packets as a means of dealing fragments of IPv6 LISP-encapsulated packets as a means of dealing
with MTU issues should also use implementation techniques in ETRs to with MTU issues should also use implementation techniques in ETRs to
prevent this from being a DoS attack vector. Limits on the number of prevent this from being a DoS attack vector. Limits on the number of
fragments awaiting reassembly at an ETR, RTR, or PETR, and the rate fragments awaiting reassembly at an ETR, RTR, or PETR, and the rate
of admitting such fragments may be used. of admitting such fragments, may be used.
17. Network Management Considerations 17. Network Management Considerations
Considerations for network management tools exist so the LISP Considerations for network management tools exist so the LISP
protocol suite can be operationally managed. These mechanisms can be protocol suite can be operationally managed. These mechanisms can be
found in [RFC7052] and [RFC6835]. found in [RFC7052] and [RFC6835].
18. Changes since RFC 6830 18. Changes since RFC 6830
For implementation considerations, the following changes have been For implementation considerations, the following changes have been
made to this document since RFC 6830 was published: made to this document since [RFC6830] was published:
o It is no longer mandated that a maximum number of 2 LISP headers * It is no longer mandated that a maximum number of 2 LISP headers
be prepended to a packet. If there is a application need for more be prepended to a packet. If there is an application need for
than 2 LISP headers, an implementation can support more. However, more than 2 LISP headers, an implementation can support more.
it is RECOMMENDED that a maximum of two LISP headers can be However, it is RECOMMENDED that a maximum of 2 LISP headers can be
prepended to a packet. prepended to a packet.
o The 3 reserved flag bits in the LISP header have been allocated * The 3 reserved flag bits in the LISP header have been allocated
for [RFC8061]. The low-order 2 bits of the 3-bit field (now named for [RFC8061]. The low-order 2 bits of the 3-bit field (now named
the KK bits) are used as a key identifier. The 1 remaining bit is the KK-bits) are used as a key identifier. The 1 remaining bit is
still documented as reserved and unassigned. still documented as reserved and unassigned.
o Data-Plane gleaning for creating map-cache entries has been made * Data plane gleaning for creating Map-Cache entries has been made
optional. Any ITR implementations that depend on or assume the optional. Any ITR implementations that depend on or assume that
remote ETR is gleaning should not do so. This does not create any the remote ETR is gleaning should not do so. This does not create
interoperability problems since the control-plane map-cache any interoperability problems, since the control plane Map-Cache
population procedures are unilateral and are the typical method population procedures are unilateral and are the typical method
for map-cache population. for populating the Map-Cache.
o The bulk of the changes to this document which reduces its length * Most of the changes to this document, which reduce its length, are
are due to moving the LISP control-plane messaging and procedures due to moving the LISP control plane messaging and procedures to
to [I-D.ietf-lisp-rfc6833bis]. [RFC9301].
19. IANA Considerations 19. IANA Considerations
This section provides guidance to the Internet Assigned Numbers This section provides guidance to the Internet Assigned Numbers
Authority (IANA) regarding registration of values related to this Authority (IANA) regarding registration of values related to this
Data-Plane LISP specification, in accordance with BCP 26 [RFC8126]. data plane LISP specification, in accordance with BCP 26 [RFC8126].
19.1. LISP UDP Port Numbers 19.1. LISP UDP Port Numbers
The IANA registry has allocated UDP port number 4341 for the LISP IANA has allocated UDP port number 4341 for the LISP data plane.
Data-Plane. IANA has updated the description for UDP port 4341 as IANA has updated the description for UDP port 4341 as follows:
follows:
lisp-data 4341 udp LISP Data Packets +==============+=============+===========+=============+===========+
| Service Name | Port Number | Transport | Description | Reference |
| | | Protocol | | |
+==============+=============+===========+=============+===========+
| lisp-data | 4341 | udp | LISP Data | RFC 9300 |
| | | | Packets | |
+--------------+-------------+-----------+-------------+-----------+
Table 1
20. References 20. References
20.1. Normative References 20.1. Normative References
[I-D.ietf-lisp-6834bis]
Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID
Separation Protocol (LISP) Map-Versioning", draft-ietf-
lisp-6834bis-07 (work in progress), October 2020.
[I-D.ietf-lisp-rfc6833bis]
Farinacci, D., Maino, F., Fuller, V., and A. Cabellos-
Aparicio, "Locator/ID Separation Protocol (LISP) Control-
Plane", draft-ietf-lisp-rfc6833bis-29 (work in progress),
September 2020.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980, DOI 10.17487/RFC0768, August 1980,
<https://www.rfc-editor.org/info/rfc768>. <https://www.rfc-editor.org/info/rfc768>.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981, DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>. <https://www.rfc-editor.org/info/rfc791>.
[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>.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS "Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474, Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998, DOI 10.17487/RFC2474, December 1998,
<https://www.rfc-editor.org/info/rfc2474>. <https://www.rfc-editor.org/info/rfc2474>.
[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
May 2000, <https://www.rfc-editor.org/info/rfc2827>.
[RFC2983] Black, D., "Differentiated Services and Tunnels", [RFC2983] Black, D., "Differentiated Services and Tunnels",
RFC 2983, DOI 10.17487/RFC2983, October 2000, RFC 2983, DOI 10.17487/RFC2983, October 2000,
<https://www.rfc-editor.org/info/rfc2983>. <https://www.rfc-editor.org/info/rfc2983>.
[RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion [RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion
Notification", RFC 6040, DOI 10.17487/RFC6040, November Notification", RFC 6040, DOI 10.17487/RFC6040, November
2010, <https://www.rfc-editor.org/info/rfc6040>. 2010, <https://www.rfc-editor.org/info/rfc6040>.
[RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label [RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label
for Equal Cost Multipath Routing and Link Aggregation in for Equal Cost Multipath Routing and Link Aggregation in
skipping to change at page 37, line 19 skipping to change at line 1651
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
[RFC8378] Moreno, V. and D. Farinacci, "Signal-Free Locator/ID [RFC8378] Moreno, V. and D. Farinacci, "Signal-Free Locator/ID
Separation Protocol (LISP) Multicast", RFC 8378, Separation Protocol (LISP) Multicast", RFC 8378,
DOI 10.17487/RFC8378, May 2018, DOI 10.17487/RFC8378, May 2018,
<https://www.rfc-editor.org/info/rfc8378>. <https://www.rfc-editor.org/info/rfc8378>.
[RFC8704] Sriram, K., Montgomery, D., and J. Haas, "Enhanced
Feasible-Path Unicast Reverse Path Forwarding", BCP 84,
RFC 8704, DOI 10.17487/RFC8704, February 2020,
<https://www.rfc-editor.org/info/rfc8704>.
[RFC9301] Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,
Ed., "Locator/ID Separation Protocol (LISP) Control
Plane", RFC 9301, DOI 10.17487/RFC9301, October 2022,
<https://www.rfc-editor.org/info/rfc9301>.
[RFC9302] Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID
Separation Protocol (LISP) Map-Versioning", RFC 9302,
DOI 10.17487/RFC9302, October 2022,
<https://www.rfc-editor.org/info/rfc9302>.
20.2. Informative References 20.2. Informative References
[AFN] IANA, "Address Family Numbers", August 2016, [AFN] IANA, "Address Family Numbers",
<http://www.iana.org/assignments/address-family-numbers>. <http://www.iana.org/assignments/address-family-numbers>.
[CHIAPPA] Chiappa, J., "Endpoints and Endpoint names: A Proposed", [CHIAPPA] Chiappa, J., "Endpoints and Endpoint Names: A Proposed
1999, Enhancement to the Internet Architecture", 1999,
<http://mercury.lcs.mit.edu/~jnc/tech/endpoints.txt>. <http://mercury.lcs.mit.edu/~jnc/tech/endpoints.txt>.
[I-D.ietf-lisp-introduction] [LISP-VPN] Moreno, V. and D. Farinacci, "LISP Virtual Private
Cabellos-Aparicio, A. and D. Saucez, "An Architectural Networks (VPNs)", Work in Progress, Internet-Draft, draft-
Introduction to the Locator/ID Separation Protocol ietf-lisp-vpn-10, 3 October 2022,
(LISP)", draft-ietf-lisp-introduction-13 (work in <https://datatracker.ietf.org/doc/html/draft-ietf-lisp-
progress), April 2015. vpn-10>.
[I-D.ietf-lisp-vpn]
Moreno, V. and D. Farinacci, "LISP Virtual Private
Networks (VPNs)", draft-ietf-lisp-vpn-06 (work in
progress), August 2020.
[I-D.ietf-tsvwg-datagram-plpmtud]
Fairhurst, G., Jones, T., Tuexen, M., Ruengeler, I., and
T. Voelker, "Packetization Layer Path MTU Discovery for
Datagram Transports", draft-ietf-tsvwg-datagram-plpmtud-22
(work in progress), June 2020.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>. <https://www.rfc-editor.org/info/rfc1034>.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990, DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>. <https://www.rfc-editor.org/info/rfc1191>.
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., [RFC2453] Malkin, G., "RIP Version 2", STD 56, RFC 2453,
and E. Lear, "Address Allocation for Private Internets", DOI 10.17487/RFC2453, November 1998,
BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, <https://www.rfc-editor.org/info/rfc2453>.
<https://www.rfc-editor.org/info/rfc1918>.
[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery [RFC2677] Greene, M., Cucchiara, J., and J. Luciani, "Definitions of
for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August Managed Objects for the NBMA Next Hop Resolution Protocol
1996, <https://www.rfc-editor.org/info/rfc1981>. (NHRP)", RFC 2677, DOI 10.17487/RFC2677, August 1999,
<https://www.rfc-editor.org/info/rfc2677>.
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
DOI 10.17487/RFC2784, March 2000, DOI 10.17487/RFC2784, March 2000,
<https://www.rfc-editor.org/info/rfc2784>. <https://www.rfc-editor.org/info/rfc2784>.
[RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains
via IPv4 Clouds", RFC 3056, DOI 10.17487/RFC3056, February via IPv4 Clouds", RFC 3056, DOI 10.17487/RFC3056, February
2001, <https://www.rfc-editor.org/info/rfc3056>. 2001, <https://www.rfc-editor.org/info/rfc3056>.
[RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced
by an On-line Database", RFC 3232, DOI 10.17487/RFC3232,
January 2002, <https://www.rfc-editor.org/info/rfc3232>.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002, DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/info/rfc3261>. <https://www.rfc-editor.org/info/rfc3261>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, "Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005, DOI 10.17487/RFC4086, June 2005,
<https://www.rfc-editor.org/info/rfc4086>. <https://www.rfc-editor.org/info/rfc4086>.
[RFC4459] Savola, P., "MTU and Fragmentation Issues with In-the- [RFC4459] Savola, P., "MTU and Fragmentation Issues with In-the-
Network Tunneling", RFC 4459, DOI 10.17487/RFC4459, April Network Tunneling", RFC 4459, DOI 10.17487/RFC4459, April
2006, <https://www.rfc-editor.org/info/rfc4459>. 2006, <https://www.rfc-editor.org/info/rfc4459>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
<https://www.rfc-editor.org/info/rfc4821>. <https://www.rfc-editor.org/info/rfc4821>.
[RFC4984] Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report [RFC4984] Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report
from the IAB Workshop on Routing and Addressing", from the IAB Workshop on Routing and Addressing",
RFC 4984, DOI 10.17487/RFC4984, September 2007, RFC 4984, DOI 10.17487/RFC4984, September 2007,
<https://www.rfc-editor.org/info/rfc4984>. <https://www.rfc-editor.org/info/rfc4984>.
[RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
skipping to change at page 40, line 5 skipping to change at line 1781
[RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol [RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol
(LISP) Data-Plane Confidentiality", RFC 8061, (LISP) Data-Plane Confidentiality", RFC 8061,
DOI 10.17487/RFC8061, February 2017, DOI 10.17487/RFC8061, February 2017,
<https://www.rfc-editor.org/info/rfc8061>. <https://www.rfc-editor.org/info/rfc8061>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <https://www.rfc-editor.org/info/rfc8085>. March 2017, <https://www.rfc-editor.org/info/rfc8085>.
Appendix A. Acknowledgments [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed.,
"Path MTU Discovery for IP version 6", STD 87, RFC 8201,
DOI 10.17487/RFC8201, July 2017,
<https://www.rfc-editor.org/info/rfc8201>.
[RFC8899] Fairhurst, G., Jones, T., TΓΌxen, M., RΓΌngeler, I., and T.
VΓΆlker, "Packetization Layer Path MTU Discovery for
Datagram Transports", RFC 8899, DOI 10.17487/RFC8899,
September 2020, <https://www.rfc-editor.org/info/rfc8899>.
[RFC9299] Cabellos, A. and D. Saucez, Ed., "An Architectural
Introduction to the Locator/ID Separation Protocol
(LISP)", RFC 9299, DOI 10.17487/RFC9299, October 2022,
<https://www.rfc-editor.org/info/rfc9299>.
Acknowledgments
An initial thank you goes to Dave Oran for planting the seeds for the An initial thank you goes to Dave Oran for planting the seeds for the
initial ideas for LISP. His consultation continues to provide value initial ideas for LISP. His consultation continues to provide value
to the LISP authors. to the LISP authors.
A special and appreciative thank you goes to Noel Chiappa for A special and appreciative thank you goes to Noel Chiappa for
providing architectural impetus over the past decades on separation providing architectural impetus over the past decades on separation
of location and identity, as well as detailed reviews of the LISP of location and identity, as well as detailed reviews of the LISP
architecture and documents, coupled with enthusiasm for making LISP a architecture and documents, coupled with enthusiasm for making LISP a
practical and incremental transition for the Internet. practical and incremental transition for the Internet.
skipping to change at page 40, line 34 skipping to change at line 1825
Bonaventure, Luigi Iannone, Robin Whittle, Brian Carpenter, Joel Bonaventure, Luigi Iannone, Robin Whittle, Brian Carpenter, Joel
Halpern, Terry Manderson, Roger Jorgensen, Ran Atkinson, Stig Venaas, Halpern, Terry Manderson, Roger Jorgensen, Ran Atkinson, Stig Venaas,
Iljitsch van Beijnum, Roland Bless, Dana Blair, Bill Lynch, Marc Iljitsch van Beijnum, Roland Bless, Dana Blair, Bill Lynch, Marc
Woolward, Damien Saucez, Damian Lezama, Attilla De Groot, Parantap Woolward, Damien Saucez, Damian Lezama, Attilla De Groot, Parantap
Lahiri, David Black, Roque Gagliano, Isidor Kouvelas, Jesper Skriver, Lahiri, David Black, Roque Gagliano, Isidor Kouvelas, Jesper Skriver,
Fred Templin, Margaret Wasserman, Sam Hartman, Michael Hofling, Pedro Fred Templin, Margaret Wasserman, Sam Hartman, Michael Hofling, Pedro
Marques, Jari Arkko, Gregg Schudel, Srinivas Subramanian, Amit Jain, Marques, Jari Arkko, Gregg Schudel, Srinivas Subramanian, Amit Jain,
Xu Xiaohu, Dhirendra Trivedi, Yakov Rekhter, John Scudder, John Xu Xiaohu, Dhirendra Trivedi, Yakov Rekhter, John Scudder, John
Drake, Dimitri Papadimitriou, Ross Callon, Selina Heimlich, Job Drake, Dimitri Papadimitriou, Ross Callon, Selina Heimlich, Job
Snijders, Vina Ermagan, Fabio Maino, Victor Moreno, Chris White, Snijders, Vina Ermagan, Fabio Maino, Victor Moreno, Chris White,
Clarence Filsfils, Alia Atlas, Florin Coras and Alberto Rodriguez. Clarence Filsfils, Alia Atlas, Florin Coras, and Alberto Rodriguez.
This work originated in the Routing Research Group (RRG) of the IRTF. This work originated in the Routing Research Group (RRG) of the IRTF.
An individual submission was converted into the IETF LISP working An individual submission was converted into the IETF LISP Working
group document that became this RFC. Group document that became this RFC.
The LISP working group would like to give a special thanks to Jari The LISP Working Group would like to give a special thanks to Jari
Arkko, the Internet Area AD at the time that the set of LISP Arkko, the Internet Area AD at the time that the set of LISP
documents were being prepared for IESG last call, and for his documents was being prepared for IESG Last Call, for his meticulous
meticulous reviews and detailed commentaries on the 7 working group reviews and detailed commentaries on the 7 Working Group Last Call
last call documents progressing toward standards-track RFCs. documents progressing toward Standards Track RFCs.
The current authors would like to give a sincere thank you to the The current authors would like to give a sincere thank you to the
people who help put LISP on standards track in the IETF. They people who helped put LISP on the Standards Track in the IETF. They
include Joel Halpern, Luigi Iannone, Deborah Brungard, Fabio Maino, include Joel Halpern, Luigi Iannone, Deborah Brungard, Fabio Maino,
Scott Bradner, Kyle Rose, Takeshi Takahashi, Sarah Banks, Pete Scott Bradner, Kyle Rose, Takeshi Takahashi, Sarah Banks, Pete
Resnick, Colin Perkins, Mirja Kuhlewind, Francis Dupont, Benjamin Resnick, Colin Perkins, Mirja KΓΌhlewind, Francis Dupont, Benjamin
Kaduk, Eric Rescorla, Alvaro Retana, Alexey Melnikov, Alissa Cooper, Kaduk, Eric Rescorla, Alvaro Retana, Alexey Melnikov, Alissa Cooper,
Suresh Krishnan, Alberto Rodriguez-Natal, Vina Ermagen, Mohamed Suresh Krishnan, Alberto Rodriguez-Natal, Vina Ermagan, Mohamed
Boucadair, Brian Trammell, Sabrina Tanamal, and John Drake. The Boucadair, Brian Trammell, Sabrina Tanamal, and John Drake. The
contributions they offered greatly added to the security, scale, and contributions they offered greatly added to the security, scale, and
robustness of the LISP architecture and protocols. robustness of the LISP architecture and protocols.
Appendix B. Document Change Log
[RFC Editor: Please delete this section on publication as RFC.]
B.1. Changes to draft-ietf-lisp-rfc6830bis-27
o Posted November 2019.
o Fixed how LSB behave in the presence of new/removed locators.
o Added ETR synchronization requirements when using Map-Versioning.
o Fixed a large set of minor comments and edits.
B.2. Changes to draft-ietf-lisp-rfc6830bis-27
o Posted April 2019 post telechat.
o Made editorial corrections per Warren's suggestions.
o Put in suggested text from Luigi that Mirja agreed with.
o LSB, Echo-Nonce and Map-Versioning SHOULD be only used in closed
environments.
o Removed paragraph stating that Instance-ID can be 32-bit in the
control-plane.
o 6831/8378 are now normative.
o Rewritten Security Considerations according to the changes.
o Stated that LSB SHOULD be coupled with Map-Versioning.
B.3. Changes to draft-ietf-lisp-rfc6830bis-26
o Posted late October 2018.
o Changed description about "reserved" bits to state "reserved and
unassigned".
B.4. Changes to draft-ietf-lisp-rfc6830bis-25
o Posted mid October 2018.
o Added more to the Security Considerations section with discussion
about echo-nonce attacks.
B.5. Changes to draft-ietf-lisp-rfc6830bis-24
o Posted mid October 2018.
o Final editorial changes for Eric and Ben.
B.6. Changes to draft-ietf-lisp-rfc6830bis-23
o Posted early October 2018.
o Added an applicability statement in section 1 to address security
concerns from Telechat.
B.7. Changes to draft-ietf-lisp-rfc6830bis-22
o Posted early October 2018.
o Changes to reflect comments post Telechat.
B.8. Changes to draft-ietf-lisp-rfc6830bis-21
o Posted late-September 2018.
o Changes to reflect comments from Sep 27th Telechat.
B.9. Changes to draft-ietf-lisp-rfc6830bis-20
o Posted late-September 2018.
o Fix old reference to RFC3168, changed to RFC6040.
B.10. Changes to draft-ietf-lisp-rfc6830bis-19
o Posted late-September 2018.
o More editorial changes.
B.11. Changes to draft-ietf-lisp-rfc6830bis-18
o Posted mid-September 2018.
o Changes to reflect comments from Secdir review (Mirja).
B.12. Changes to draft-ietf-lisp-rfc6830bis-17
o Posted September 2018.
o Indicate in the "Changes since RFC 6830" section why the document
has been shortened in length.
o Make reference to RFC 8085 about UDP congestion control.
o More editorial changes from multiple IESG reviews.
B.13. Changes to draft-ietf-lisp-rfc6830bis-16
o Posted late August 2018.
o Distinguish the message type names between ICMP for IPv4 and ICMP
for IPv6 for handling MTU issues.
B.14. Changes to draft-ietf-lisp-rfc6830bis-15
o Posted August 2018.
o Final editorial changes before RFC submission for Proposed
Standard.
o Added section "Changes since RFC 6830" so implementers are
informed of any changes since the last RFC publication.
B.15. Changes to draft-ietf-lisp-rfc6830bis-14
o Posted July 2018 IETF week.
o Put obsolete of RFC 6830 in Intro section in addition to abstract.
B.16. Changes to draft-ietf-lisp-rfc6830bis-13
o Posted March IETF Week 2018.
o Clarified that a new nonce is required per RLOC.
o Removed 'Clock Sweep' section. This text must be placed in a new
OAM document.
o Some references changed from normative to informative
B.17. Changes to draft-ietf-lisp-rfc6830bis-12
o Posted July 2018.
o Fixed Luigi editorial comments to ready draft for RFC status.
B.18. Changes to draft-ietf-lisp-rfc6830bis-11
o Posted March 2018.
o Removed sections 16, 17 and 18 (Mobility, Deployment and
Traceroute considerations). This text must be placed in a new OAM
document.
B.19. Changes to draft-ietf-lisp-rfc6830bis-10
o Posted March 2018.
o Updated section 'Router Locator Selection' stating that the Data-
Plane MUST follow what's stored in the Map-Cache (priorities and
weights).
o Section 'Routing Locator Reachability': Removed bullet point 2
(ICMP Network/Host Unreachable),3 (hints from BGP),4 (ICMP Port
Unreachable),5 (receive a Map-Reply as a response) and RLOC
probing
o Removed 'Solicit-Map Request'.
B.20. Changes to draft-ietf-lisp-rfc6830bis-09
o Posted January 2018.
o Add more details in section 5.3 about DSCP processing during
encapsulation and decapsulation.
o Added clarity to definitions in the Definition of Terms section
from various commenters.
o Removed PA and PI definitions from Definition of Terms section.
o More editorial changes.
o Removed 4342 from IANA section and move to RFC6833 IANA section.
B.21. Changes to draft-ietf-lisp-rfc6830bis-08
o Posted January 2018.
o Remove references to research work for any protocol mechanisms.
o Document scanned to make sure it is RFC 2119 compliant.
o Made changes to reflect comments from document WG shepherd Luigi
Iannone.
o Ran IDNITs on the document.
B.22. Changes to draft-ietf-lisp-rfc6830bis-07
o Posted November 2017.
o Rephrase how Instance-IDs are used and don't refer to [RFC1918]
addresses.
B.23. Changes to draft-ietf-lisp-rfc6830bis-06
o Posted October 2017.
o Put RTR definition before it is used.
o Rename references that are now working group drafts.
o Remove "EIDs MUST NOT be used as used by a host to refer to other
hosts. Note that EID blocks MAY LISP RLOCs".
o Indicate what address-family can appear in data packets.
o ETRs may, rather than will, be the ones to send Map-Replies.
o Recommend, rather than mandate, max encapsulation headers to 2.
o Reference VPN draft when introducing Instance-ID.
o Indicate that SMRs can be sent when ITR/ETR are in the same node.
o Clarify when private addresses can be used.
B.24. Changes to draft-ietf-lisp-rfc6830bis-05
o Posted August 2017.
o Make it clear that a Re-encapsulating Tunnel Router is an RTR.
B.25. Changes to draft-ietf-lisp-rfc6830bis-04
o Posted July 2017.
o Changed reference of IPv6 RFC2460 to RFC8200.
o Indicate that the applicability statement for UDP zero checksums
over IPv6 adheres to RFC6936.
B.26. Changes to draft-ietf-lisp-rfc6830bis-03
o Posted May 2017.
o Move the control-plane related codepoints in the IANA
Considerations section to RFC6833bis.
B.27. Changes to draft-ietf-lisp-rfc6830bis-02
o Posted April 2017.
o Reflect some editorial comments from Damien Sausez.
B.28. Changes to draft-ietf-lisp-rfc6830bis-01
o Posted March 2017.
o Include references to new RFCs published.
o Change references from RFC6833 to RFC6833bis.
o Clarified LCAF text in the IANA section.
o Remove references to "experimental".
B.29. Changes to draft-ietf-lisp-rfc6830bis-00
o Posted December 2016.
o Created working group document from draft-farinacci-lisp
-rfc6830-00 individual submission. No other changes made.
Authors' Addresses Authors' Addresses
Dino Farinacci Dino Farinacci
lispers.net lispers.net
San Jose, CA
United States of America
Email: farinacci@gmail.com
EMail: farinacci@gmail.com
Vince Fuller Vince Fuller
vaf.net Internet Consulting vaf.net Internet Consulting
Email: vince.fuller@gmail.com
EMail: vince.fuller@gmail.com
Dave Meyer Dave Meyer
1-4-5.net 1-4-5.net
Email: dmm@1-4-5.net
EMail: dmm@1-4-5.net
Darrel Lewis Darrel Lewis
Cisco Systems Cisco Systems
170 Tasman Drive
San Jose, CA San Jose, CA
USA United States of America
Email: darlewis@cisco.com
EMail: darlewis@cisco.com
Albert Cabellos Albert Cabellos (editor)
UPC/BarcelonaTech Universitat Politecnica de Catalunya
Campus Nord, C. Jordi Girona 1-3 c/ Jordi Girona s/n
Barcelona, Catalunya 08034 Barcelona
Spain Spain
Email: acabello@ac.upc.edu
EMail: acabello@ac.upc.edu
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