Internet-Draft OSPF for BIER-TE February 2024
Chen, et al. Expires 4 August 2024 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-ietf-bier-te-ospf-10
Published:
Intended Status:
Standards Track
Expires:
Authors:
H. Chen
Futurewei
M. McBride
Futurewei
Z. Zhang
ZTE Corporation
A. Wang
China Telecom
G. Mishra
Verizon Inc.
Y. Fan
Casa Systems

OSPF Extensions for BIER-TE

Abstract

This document describes OSPFv2 and OSPFv3 extensions for distributing the BitPositions configured on a Bit-Forwarding Router (BFR) with MPLS and non-MPLS encapsulation for "Bit Index Explicit Replication Traffic Engineering" (BIER-TE) in a BIER-TE domain.

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."

This Internet-Draft will expire on 4 August 2024.

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.

[RFC8444] describes OSPFv2 Extensions for distributing the BFR identifier (BFR-id) configured on a BFR. [I-D.ietf-bier-ospfv3-extensions] describes OSPFv3 Extensions for distributing the BFR identifier (BFR-id) configured on a BFR. The advertisement of MPLS and Non-MPLS encapsulation for BIER is speficied in [RFC8444], [I-D.ietf-bier-ospfv3-extensions], and [I-D.ietf-bier-lsr-non-mpls-extensions]. This document specifies OSPFv2 and OSPFv3 extensions for distributing the BitPositions configured on a BFR with MPLS and Non-MPLS encapsulation for BIER-TE 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 OSPFv2

This section describes protocol extensions to OSPFv2 for distributing the BitPositions configured on a BFR in a BIER-TE domain.

This section defines a Sub-TLV for distributing a link BitPosition (BP).

[RFC7684] defines the OSPFv2 Extended Link TLV to advertise the information about a link. Only one OSPFv2 Extended Link TLV SHALL be advertised in each OSPFv2 Extended Link Opaque LSA. The OSPFv2 Extended Link TLV has the following format:

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.

Under the OSPFv2 Extended Link TLV for a link, a Sub-TLV, called Link-BP Sub-TLV, is defined for distributing a link BitPosition. A Link-BP Sub-TLV is included in the Link TLV for a link of Link Type P2P (Point-to-Point) or Broadcast (or say LAN or Transit Network). The Link-BP Sub-TLV has the following format:

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 [RFC8444].
BitPosition:
A 2-octet field encoding the BitPosition locally configured on the link/interface 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) 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 OSPFv2 Extended 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

A TLV, called Node BPs TLV, is defined within the body of the OSPF Router Information (RI) Opaque Link State Advertisement (LSA) [RFC7770]. The TLV contains Sub-TLVs. Two types of Sub-TLVs are defined. One is for a Routed BitPosition and the other for a Localdecap BitPosition.

The Node BPs 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 (TBD2)          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | sub-domain-id |     MT-ID     |      BAR      |    IPA        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            Sub-TLVs                           ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Node BPs TLV
Type:
TBD2 is to be assigned by IANA.
Length:
Variable.
sub-domain-id, MT-ID, BAR and IPA:
They are defined in Section 2.1 of [RFC8444].
Sub-TLVs:
They are Routed-BP Sub-TLVs for Routed BPs and/or Localdecap-BP Sub-TLV for Localdecap BP.

The Routed-BP 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(4)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         BitPosition           |             BFR-id            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Routed-BP Sub-TLV
Type:
TBD3 is to be assigned by IANA..
Length:
It is 4.
BitPosition:
A 2-octet field encoding the BitPosition configured on a BFR for a forward routed adjacency to a remote BFR.
BFR-id:
A 2-octet field encoding the BFR-id of the remote BFR.

The Localdecap-BP 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 (TBD4)          |           Length(2)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         BitPosition           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Localdecap-BP Sub-TLV
Type:
TBD4 is to be assigned by IANA.
Length:
It is 2.
BitPosition:
A 2-octet field encoding the localdecap BitPosition configured on a BFR.

2.3. BIER-TE Encapsulation Sub-TLVs

Two BIER-TE Encapsulation Sub-TLVs are defined. One is BIER-TE MPLS Encapsulation Sub-TLV and the other is BIER-TE non-MPLS Encapsulation Sub-TLV. They are similar to the BIER MPLS Encapsulation Sub-TLV defined in Section 2.2 of [RFC8444]. They are advertised with the Node BPs TLV. Their flooding scope is the same as the one in Section 2.3 of [RFC8444].

2.3.1. BIER-TE MPLS Encapsulation Sub-TLV

The format of BIER-TE MPLS Encapsulation Sub-TLV is illustrated in Figure 6.

    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 (TBD5)         |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Max SI    |                  Label                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | BS Len|                   Reserved                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: BIER-TE MPLS Encapsulation Sub-TLV

Type: TBD5 is to be assigned by IANA.

Length: 8.

Max SI: A 1 octet field encoding the maximum Set Identifier (Section 1 of [RFC8279]), used in the encapsulation for this BIER-TE sub-domain for this bitstring length.

Label: A 3 octet field, where the 20 rightmost bits represent the first label in the label range. The 4 leftmost bits MUST be ignored.

BS Len: A 4 bits field encoding the supported BitString length associated with the BPs configured on the BFR and in the BP Sub-TLVs and TLV with the BIER-TE Encapsulation Sub-TLV. The values allowed in this field are specified in Section 2 of [RFC8296].

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

2.3.2. BIER-TE Non-MPLS Encapsulation Sub-TLV

The format of BIER-TE Non-MPLS Encapsulation Sub-TLV is illustrated in Figure 7.

    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 (TBD6)         |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Max SI    |                  BIFT-ID                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | BS Len|                   Reserved                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: BIER-TE Non-MPLS Encapsulation Sub-TLV

Type: TBD6 is to be assigned by IANA.

Length: 8.

BIFT-ID: A 3 octet field, where the 20 rightmost bits represent the first value in the value range. The 4 leftmost bits MUST be ignored.

The other fields are the same as those for BIER-TE MPLS Encapsulation Sub-TLV.

3. Extensions to OSPFv3

This section describes protocol extensions to OSPFv3 for distributing the BitPositions configured on a BFR 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 Link-BP Sub-TLV below for distributing a link BP.

Type:
TBD7 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].

3.2. Routed and Localdecap BitPositions

The Node BPs TLV, Routed BP Sub-TLV and Localdecap BP Sub-TLV defined in Section 2.2 are reused in OSPVv3 for distributing the routed BitPositions and the localdecap BitPosition configured on a BFR.

3.3. BIER-TE Encapsulation Sub-TLVs

Two BIER-TE Encapsulation Sub-TLVs defined in Section 2.3 are reused in OSPFv3. They are similar to the BIER MPLS Encapsulation Sub-TLV defined in Section 2.2 of [I-D.ietf-bier-ospfv3-extensions]. They are advertised with the Node BPs TLV. Their flooding scope is the same as the one in Section 2.3 of [I-D.ietf-bier-ospfv3-extensions].

4. Security Considerations

Protocol extensions defined in this document do not affect the OSPF security other than those as discussed in the Security Considerations section of [RFC7684] and [RFC8362].

5. IANA Considerations

5.1. OSPFv2

Under "OSPFv2 Extended Link TLV Sub-TLVs" registry as defined in [RFC7684], IANA is requested to assign a new registry value for Link-BP Sub-TLV, BIER-TE MPLS Encapsulation Sub-TLV and BIER-TE Non-MPLS Encapsulation Sub-TLV as follows:

  +===========+================================+===============+
  |  Value    |  Description                   |  reference    |
  +===========+================================+===============+
  | TBD1 (30) |  Link-BP                       | This document |
  +-----------+--------------------------------+---------------+
  | TBD5 (31) | BIER-TE MPLS Encapsulation     | This document |
  +-----------+--------------------------------+---------------+
  | TBD6 (32) | BIER-TE Non-MPLS Encapsulation | This document |
  +-----------+--------------------------------+---------------+

Under "OSPF Router Information (RI) TLVs" registry as defined in [RFC7770], IANA is requested to assign a new registry value for Node BPs TLV as follows:

  +==============+===================+=====================+
  |  Value       |  Description      |    reference        |
  +==============+===================+=====================+
  |  TBD2 (21)   |  Node BPs         |    This document    |
  +--------------+-------------------+---------------------+

IANA is requested to create a new subregistry called the "OSPF Node BPs Sub-TLVs" under the "Open Shortest Path First (OSPF) Parameters" registry. The initial values are as follows:

  +=============+================================+===============+
  |    Value    |  Description                   |  reference    |
  +=============+================================+===============+
  |      0      |  Reserved                      | This document |
  +-------------+--------------------------------+---------------+
  |  TBD3(1)    |  Routed BP                     | This document |
  +-------------+--------------------------------+---------------+
  |  TBD4(2)    |  Localdecap BP                 | This document |
  +-------------+--------------------------------+---------------+
  |       31    | BIER-TE MPLS Encapsulation     | This document |
  +-------------+--------------------------------+---------------+
  |       32    | BIER-TE Non-MPLS Encapsulation | This document |
  +-------------+--------------------------------+---------------+
  |3-30,33-65535|  To be allocated in First Come First Served    |
  +-------------+--------------------------------+---------------+

5.2. OSPFv3

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, BIER-TE MPLS Encapsulation Sub-TLV and BIER-TE Non-MPLS Encapsulation Sub-TLV as follows:

  +===========+================================+===============+
  |  Value    |  Description                   |  reference    |
  +===========+================================+===============+
  | TBD7 (30) |  Link-BP                       | This document |
  +-----------+--------------------------------+---------------+
  |       31  | BIER-TE MPLS Encapsulation     | This document |
  +-----------+--------------------------------+---------------+
  |       32  | BIER-TE Non-MPLS Encapsulation | This document |
  +-----------+--------------------------------+---------------+

6. References

6.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC2328]
Moy, J., "OSPF Version 2", STD 54, RFC 2328, DOI 10.17487/RFC2328, , <https://www.rfc-editor.org/info/rfc2328>.
[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, , <https://www.rfc-editor.org/info/rfc7684>.
[RFC7770]
Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, , <https://www.rfc-editor.org/info/rfc7770>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <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, , <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, , <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, , <https://www.rfc-editor.org/info/rfc9262>.

6.2. 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-08, , <https://datatracker.ietf.org/doc/html/draft-chen-bier-te-lan-08>.
[I-D.ietf-bier-lsr-non-mpls-extensions]
Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang, Z. J., and J. Xie, "LSR Extensions for BIER non-MPLS Encapsulation", Work in Progress, Internet-Draft, draft-ietf-bier-lsr-non-mpls-extensions-02, , <https://datatracker.ietf.org/doc/html/draft-ietf-bier-lsr-non-mpls-extensions-02>.
[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, , <https://datatracker.ietf.org/doc/html/draft-ietf-bier-ospfv3-extensions-07>.
[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, , <https://www.rfc-editor.org/info/rfc8296>.
[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, , <https://www.rfc-editor.org/info/rfc8444>.

Acknowledgments

The authors would like to thank Acee Lindem, Les Ginsberg, Tony Przygienda, Jeffrey Zhang and Toerless Eckert for their comments on this work.

Contributors' Addresses 

   Yuehua Wei
   ZTE Corporation
   China
   Email: wei.yuehua@zte.com.cn

   Lei Liu
   Fujitsu
   USA
   Email: liulei.kddi@gmail.com

   Benchong Xu
   ZTE Corporation
   China
   Email: xu.benchong@zte.com.cn

   Xufeng Liu
   Alef Edge
   USA
   Email: xufeng.liu.ietf@gmail.com

   IJsbrand Wijnands
   Arrcus
   Email: ice@braindump.be

Authors' Addresses

Huaimo Chen
Futurewei
Boston, MA,
United States of America
Mike McBride
Futurewei
Zheng Zhang
ZTE Corporation
China
Aijun Wang
China Telecom
Beiqijia Town, Changping District
Beijing
102209
China
Gyan S. Mishra
Verizon Inc.
13101 Columbia Pike
Silver Spring, MD 20904
United States of America
Phone: 301 502-1347
Yanhe Fan
Casa Systems
United States of America