OSPFv3 Extensions for BIER-TE

Internet-Draft	OSPFv3 for BIER-TE	July 2021
Chen, et al.	Expires 28 January 2022	[Page]

Abstract

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

Status of This Memo

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Copyright Notice

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1. Introduction

[I-D.ietf-bier-te-arch] 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. A link in a BIER-TE domain has its BitPositions. For a link between two nodes X and Y, there are two BitPositions for two forward connected adjacencies. These two adjacency BitPositions could be configured on nodes X and Y respectively. The BitPosition configured on X is the forward connected adjacency of Y. The BitPosition configured on Y is the forward connected adjacency of X.¶

This document proposes OSPFv3 extensions for distributing BitPositions configured on the links in "Bit Index Explicit Replication Traffic Engineering" (BIER-TE) domain.¶

1.1. Terminology

BIER:: Bit Index Explicit Replication.¶
BIER-TE:: BIER Traffic Engineering.¶
BFR:: Bit-Forwarding Router.¶
BFIR:: Bit-Forwarding Ingress Router.¶
BFER:: Bit-Forwarding Egress Router.¶
BFR-id:: BFR Identifier. It is a number in the range [1,65535].¶
BFR-NBR:: BFR Neighbor.¶
LSA:: Link State Advertisement.¶
OSPF:: Open Shortest Path First.¶

2. Extensions to OSPFv3

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

[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 BIER-TE Sub-TLV below for distributing BIER-TE information. This 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            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | sub-domain-id |     MT-ID     |      BAR      |    IPA        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         BitPosition           |         DrEndBitPosition      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Sub-TLVs (variable)                    |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: BIER-TE Sub-TLV in Router-Link TLV

Type:: TBD1 is to be assigned by IANA.¶
Length:: Variable, dependent on Sub-Sub-TLVs.¶
sub-domain-id:: Unique value identifying a BIER-TE sub-domain.¶
MT-ID:: Multi-Topology ID identifying the topology that is associated with the BIER-TE sub-domain.¶
BAR:: Single-octet BIER Algorithm used to calculate underlay paths to reach other BFRs. Values are allocated from the "BIER Algorithm" registry defined in [RFC8401].¶
IPA:: Single-octet IGP Algorithm used to either modify, enhance, or replace the calculation of underlay paths to reach other BFRs as defined by the BAR value. Values are defined in the "IGP Algorithm Types" registry.¶
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 is valid 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 be ignored. The DrEndBitPosition may be configured on the link/interface to a transit network (i.e., broadcast link or say LAN).¶

No Sub-TLV is defined so far. Note that if each of BitPosition and DrEndBitPosition uses more than 2 octets, we use 4 or more octets for each of them.¶

4. IANA Considerations

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

  +==============+===================+=====================+
  |  Value       |  Description      |    reference        |
  +==============+===================+=====================+
  |  TBD1 (30)   |  BIER-TE          |    This document    |
  +--------------+-------------------+---------------------+

6. References

6.1. Normative References

[I-D.ietf-bier-te-arch]: Eckert, T., Cauchie, G., and M. Menth, "Tree Engineering for Bit Index Explicit Replication (BIER-TE)", Work in Progress, Internet-Draft, draft-ietf-bier-te-arch-10, 9 July 2021, <https://www.ietf.org/archive/id/draft-ietf-bier-te-arch-10.txt>.
[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>.
[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>.
[RFC5226]: Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 5226, DOI 10.17487/RFC5226, May 2008, <https://www.rfc-editor.org/info/rfc5226>.
[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>.
[RFC8279]: Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., Przygienda, T., and S. Aldrin, "Multicast Using Bit Index Explicit Replication (BIER)", RFC 8279, DOI 10.17487/RFC8279, November 2017, <https://www.rfc-editor.org/info/rfc8279>.
[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>.

6.2. Informative References

[RFC5250]: Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250, July 2008, <https://www.rfc-editor.org/info/rfc5250>.
[RFC8296]: Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation for Bit Index Explicit Replication (BIER) in MPLS and Non-MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 2018, <https://www.rfc-editor.org/info/rfc8296>.
[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>.
[RFC8444]: Psenak, P., Ed., Kumar, N., Wijnands, IJ., Dolganow, A., Przygienda, T., Zhang, J., and S. Aldrin, "OSPFv2 Extensions for Bit Index Explicit Replication (BIER)", RFC 8444, DOI 10.17487/RFC8444, November 2018, <https://www.rfc-editor.org/info/rfc8444>.
[RFC8556]: Rosen, E., Ed., Sivakumar, M., Przygienda, T., Aldrin, S., and A. Dolganow, "Multicast VPN Using Bit Index Explicit Replication (BIER)", RFC 8556, DOI 10.17487/RFC8556, April 2019, <https://www.rfc-editor.org/info/rfc8556>.