OSPFv3 Extensions for BIER-TE

Internet-Draft	OSPFv3 for BIER-TE	July 2023
Chen, et al.	Expires 6 January 2024	[Page]

Abstract

This document describes OSPFv3 extensions for distributing the BitPositions configured on a Bit-Forwarding Router (BFR) in a "Bit Index Explicit Replication Traffic Engineering" (BIER-TE) domain.¶

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."¶

This Internet-Draft will expire on 6 January 2024.¶

Copyright Notice

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.¶

1. Introduction

[RFC9262] introduces Bit Index Explicit Replication (BIER) Traffic/Tree Engineering (BIER-TE). It is an architecture for per-packet stateless explicit point to multipoint (P2MP) multicast path/tree. There are three types of BitPositions (BPs) in a BIER-TE domain: link BitPosition (BP), routed BP and localdecap BP. A link BP is a BP configured on a link from Bit-Forwarding Router (BFR) X to BFR Y for a forward connected adjacency from X to Y. A routed BP is a BP configured on BFR X for a forward routed adjacency from X to a remote BFR Z not directly connected to X. A localdecap BP is a BP configured on a BFR.¶

[I-D.ietf-bier-ospfv3-extensions] describes OSPFv3 Extensions for distributing the BFR identifier (BFR-id) configured on a BFR. This document specifies OSPFv3 extensions for distributing the BitPositions configured a BFR in a BIER-TE domain. The BitPositions distributed may be used by a BFR as a Point of Local Repair (PLR) for Fast-ReRoute (FRR).¶

2. Extensions to OSPFv3

This section describes protocol extensions to OSPFv3 for distributing the BitPositions configured on a BFR in a BIER-TE domain.¶

2.1. Link BitPosition

[RFC8362] defines OSPFv3 Extended Router LSA, which may include multiple Router-Link TLVs. A Router-Link TLV defines a single router link. A Router-Link TLV may include a Link-BP Sub-TLV below for distributing a link BP.¶

     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            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | sub-domain-id |     MT-ID     |      BAR      |    IPA        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         BitPosition           |         DrEndBitPosition      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: Link-BP Sub-TLV in Router-Link TLV

Type:: TBD1 is to be assigned by IANA.¶
Length:: Variable.¶
sub-domain-id, MT-ID, BAR and IPA:: They are defined in Section 2.1 of [I-D.ietf-bier-ospfv3-extensions].¶
BitPosition:: A 2-octet field encoding the BitPosition locally configured on the link/interface when the Link Type of the link in the Router-Link TLV containing this Sub-TLV is 1 (i.e., Point-to-Point connection to another router) or 2 (i.e., connection to Transit Network or say LAN).¶
DrEndBitPosition:: A 2-octet field encoding the BitPosition of the connection on the designated router (DR) end. This field exists when the Link Type in the Router-Link TLV containing this Sub-TLV is 2 (i.e., Transit Network or LAN). For the other value of the Link Type, this field MUST NOT exist. The DrEndBitPosition may be configured on the link/interface to a transit network (i.e., broadcast link or say LAN) as described in [I-D.chen-bier-te-lan].¶

2.2. Routed and Localdecap BitPositions

The Node BPs TLV, Routed BP Sub-TLV and Localdecap BP Sub-TLV defined in [I-D.ietf-bier-te-ospf] are reused in OSPVv3 for distributing the routed BitPositions and the localdecap BitPosition configured on a BFR.¶

4. IANA Considerations

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

  +==============+===================+=====================+
  |  Value       |  Description      |    reference        |
  +==============+===================+=====================+
  |  TBD1 (30)   |  Link-BP          |    This document    |
  +--------------+-------------------+---------------------+

5. References

5.1. Normative References

[I-D.ietf-bier-te-ospf]: Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y., Liu, L., and X. Liu, "OSPFv2 Extensions for BIER-TE", Work in Progress, Internet-Draft, draft-ietf-bier-te-ospf-06, 5 July 2023, <https://datatracker.ietf.org/api/v1/doc/document/draft-ietf-bier-te-ospf/>.
[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>.
[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>.
[RFC9262]: Eckert, T., Ed., Menth, M., and G. Cauchie, "Tree Engineering for Bit Index Explicit Replication (BIER-TE)", RFC 9262, DOI 10.17487/RFC9262, October 2022, <https://www.rfc-editor.org/info/rfc9262>.

5.2. Informative References

[I-D.chen-bier-te-lan]: Chen, H., McBride, M., Wang, A., Mishra, G. S., Liu, L., and X. Liu, "BIER-TE for Broadcast Link", Work in Progress, Internet-Draft, draft-chen-bier-te-lan-06, 9 March 2023, <https://datatracker.ietf.org/doc/html/draft-chen-bier-te-lan-06>.
[I-D.ietf-bier-ospfv3-extensions]: Psenak, P., Nainar, N. K., and I. Wijnands, "OSPFv3 Extensions for BIER", Work in Progress, Internet-Draft, draft-ietf-bier-ospfv3-extensions-07, 1 December 2022, <https://datatracker.ietf.org/doc/html/draft-ietf-bier-ospfv3-extensions-07>.
[RFC8401]: Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. Zhang, "Bit Index Explicit Replication (BIER) Support via IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, <https://www.rfc-editor.org/info/rfc8401>.