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IGP Extensions for Advertising Link Numbers
draft-chen-lsr-adv-lkno-05

Document Type Active Internet-Draft (individual)
Authors Huaimo Chen , Donald E. Eastlake 3rd , Aijun Wang , Gyan Mishra , Yisong Liu , Yanhe Fan , Lei Liu , Xufeng Liu
Last updated 2024-09-24
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draft-chen-lsr-adv-lkno-05
Network Working Group                                            H. Chen
Internet-Draft                                               D. Eastlake
Intended status: Standards Track                             Independent
Expires: 28 March 2025                                           A. Wang
                                                           China Telecom
                                                               G. Mishra
                                                            Verizon Inc.
                                                                  Y. Liu
                                                            China Mobile
                                                                  Y. Fan
                                                            Casa Systems
                                                                  L. Liu
                                                                 Fujitsu
                                                                  X. Liu
                                                               Alef Edge
                                                       24 September 2024

              IGP Extensions for Advertising Link Numbers
                       draft-chen-lsr-adv-lkno-05

Abstract

   This document describes OSPF and IS-IS extensions for distributing
   the link numbers assigned to the links originating at a node.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119] [RFC8174]
   when, and only when, they appear in all capitals, as shown here.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

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   This Internet-Draft will expire on 28 March 2025.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Extensions to OSPFv2  . . . . . . . . . . . . . . . . . . . .   3
   3.  Extensions to OSPFv3  . . . . . . . . . . . . . . . . . . . .   4
   4.  Extensions to IS-IS . . . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   When the links originating at each node in a network are numbered
   from 1 to the number of the such links for that node, an efficient
   stateless multicast along an explicit P2MP path can be achieved
   through using the link numbers of the links on the path to represent
   the path.

   This document proposes OSPF and IS-IS extensions for distributing the
   link numbers assigned to the links originating at a node which will
   support such multicast.  After a controller such as PCE as a
   controller has the link numbers of the links originating at every
   node, for an explicit P2MP path, the controller can send the ingress
   the path represented by the link numbers of the links on the path.

1.1.  Terminology

   LSA:  Link State Advertisement.

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   OSPF:  Open Shortest Path First.

   LSP:  Link State Protocol data unit.

   IS-IS:  Intermediate System to Intermediate System.

   MT:   Multi-Topology.

   TE:   Traffic Engineering.

2.  Extensions to OSPFv2

   This section describes extensions to OSPFv2 for distributing the link
   numbers assigned to the links of a node.

   [RFC7684] defines the OSPFv2 Extended Link TLV to advertise the
   information about a link.  Multiple Link TLVs for the links of a
   router are included in the OSPFv2 Extended Link Opaque LSA of the
   router.  The OSPFv2 Extended Link TLV has the following format:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Type (1)           |      Length (Variable)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Link Type   |                    Reserved                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Link ID                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Link Data                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Sub-TLVs (variable)                     |
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 1: OSPFv2 Extended Link TLV

   Type:  1.

   Length:  Variable, dependent on Sub-TLVs.

   Link Type, Link ID and Link Data:  They are defined in Section A.4.2
         of [RFC2328].

   Reserved:  MUST be set to 0 on transmission and MUST be ignored on
         reception.

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   Under the OSPFv2 Extended Link TLV for a link, a Link Number Sub-TLV
   is defined for distributing the link number assigned to the link by
   the router originating the LSA.  A Link Number Sub-TLV is included in
   the Link TLV for a link of Link Type Point-to-Point, Broadcast (i.e.,
   link to LAN or Transit Network), or stub (i.e., link to stub
   network).  The Link Number Sub-TLV has the following format:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Type (TBD1)          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Link Number           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 2: Link Number Sub-TLV

   Type:  TBD1.  (Note this is the Sub-TLV Type, not the Link Type.)

   Length:  2.

   Link Number:  A 2-octet field carrying the link number assigned to
         the link when the Link Type of the link in the OSPFv2 Extended
         Link TLV containing this Sub-TLV is 1 (i.e., Point-to-Point
         connection to another router), 2 (i.e., connection to a Transit
         Network or LAN), or 3 (i.e., connection to a stub network).

3.  Extensions to OSPFv3

   This section describes extensions to OSPFv3 for distributing the link
   numbers assigned to the links of a node.

   [RFC8362] defines the OSPFv3 Extended Router LSA, which may include
   multiple Router-Link TLVs.

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      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              LS Age         |1|0|1|             0x21          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Link State ID                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      Advertising Router                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      LS Sequence Number                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        LS Checksum          |             Length              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  0  |N|x|V|E|B|                  Options                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                              TLVs                             |
     :                                                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 3: Extended Router-LSA

   A Router-Link TLV defines a single router link.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Type (1 - Router-Link)    |         Length (Variable)       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Link Type  |       0       |              Metric             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Interface ID                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Neighbor Interface ID                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      Neighbor Router ID                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          Sub-TLVs                             |
     :                                                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          Figure 4: Router-Link TV

   Under the Router-Link TLV for a link, a Link Number Sub-TLV is
   defined.  This Sub-TLV has the same format as the Link Number Sub-TLV
   defined above for the OSPFv2 Extended Link TLV.

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   The Router-Link TLV for a link may include a Link Number Sub-TLV for
   distributing the link number assigned to the link by the router
   originating the LSA.

4.  Extensions to IS-IS

   This section describes extensions to IS-IS for distributing the link
   numbers assigned to the links of a node.

   The Extended IS Reachability TLV (Type 22) defined in [RFC5305] may
   contain Sub-TLVs (such as those for TE (Traffic Engineering)) that
   apply to a link/interface to a neighbor.  To encode multiple links or
   interfaces to neighbors, the structure inside TLV is repeated.

   The Multi-Topology (MT) Intermediate Systems TLV (Type 222) defined
   in [RFC5120] may contain Sub-TLVs (such as those for TE) that apply
   to a link/interface.  It is aligned with the Extended IS Reachability
   TLV (Type 22) but has an additional two bytes in front at the
   beginning of the TLV for MT-ID.

   A Link Number Sub-TLV is defined and used in the Extended IS
   Reachability TLV (Type 22) and/or MT Intermediate Systems TLV (Type
   222) to advertise the link numbers assigned to the links of a node.

   The Link Number Sub-TLV has the following format:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Type (TBD3)  |    Length     |         Link Number           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 5: IS-IS Link Number Sub-TLV

   Type:  TBD3.

   Length:  2.

   Link Number:  A 2-octet field carrying the link number assigned to
         the link.

5.  Security Considerations

   TBD.

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6.  IANA Considerations

   Under "OSPFv2 Extended Link TLV Sub-TLVs registry" as defined in
   [RFC7684], IANA is requested to assign a registry value for Link
   Number Sub-TLV as follows:

     +==============+======================+=====================+
     |  Value       |  Description         |    reference        |
     +==============+======================+=====================+
     |  TBD1        |  Link Number         |    This document    |
     +--------------+----------------------+---------------------+

   Under "OSPFv3 Extended-LSA Sub-TLVs registry" as defined in
   [RFC8362], IANA is requested to assign a registry value for Link
   Number Sub-TLV as follows:

     +==============+======================+=====================+
     |  Value       |  Description         |    reference        |
     +==============+======================+=====================+
     |  TBD2        |  Link Number         |    This document    |
     +--------------+----------------------+---------------------+

   Under "Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223" for IS-IS TLV
   Codepoints, IANA is requested to assign a codepoint for Link Number
   Sub-TLV as follows:

   +============+===================+==+==+==+===+===+===+=============+
   |Sub-TLV Type|Sub-TLV Name       |22|23|25|141|222|223|reference    |
   +============+===================+==+==+==+===+===+===+=============+
   | TBD3       |Link Number        |y |n |n | n | y | n |This document|
   +------------+-------------------+--+--+--+---+---+---+-------------+

7.  Acknowledgements

   TBD.

8.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

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   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328,
              DOI 10.17487/RFC2328, April 1998,
              <https://www.rfc-editor.org/info/rfc2328>.

   [RFC5120]  Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
              Topology (MT) Routing in Intermediate System to
              Intermediate Systems (IS-ISs)", RFC 5120,
              DOI 10.17487/RFC5120, February 2008,
              <https://www.rfc-editor.org/info/rfc5120>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <https://www.rfc-editor.org/info/rfc5305>.

   [RFC7684]  Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
              Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
              Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
              2015, <https://www.rfc-editor.org/info/rfc7684>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8362]  Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
              F. Baker, "OSPFv3 Link State Advertisement (LSA)
              Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
              2018, <https://www.rfc-editor.org/info/rfc8362>.

Authors' Addresses

   Huaimo Chen
   Independent
   Boston, MA,
   United States of America
   Email: hchen.ietf@gmail.com

   Donald E. Eastlake 3rd
   Independent
   2386 Panoramic Circle
   Apopka, FL,  32703
   United States of America
   Phone: +1-508-333-2270
   Email: d3e3e3@gmail.com

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   Aijun Wang
   China Telecom
   Beiqijia Town, Changping District
   Beijing
   102209
   China
   Email: wangaj3@chinatelecom.cn

   Gyan S. Mishra
   Verizon Inc.
   13101 Columbia Pike
   Silver Spring,  MD 20904
   United States of America
   Phone: 301 502-1347
   Email: gyan.s.mishra@verizon.com

   Yisong Liu
   China Mobile
   Email: liuyisong@chinamobile.com

   Yanhe Fan
   Casa Systems
   United States of America
   Email: yfan@casa-systems.com

   Lei Liu
   Fujitsu
   United States of America
   Email: liulei.kddi@gmail.com

   Xufeng Liu
   Alef Edge
   United States of America
   Email: xufeng.liu.ietf@gmail.com

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