Internet DRAFT - draft-chen-bier-idr-bier-te-bgp

draft-chen-bier-idr-bier-te-bgp







BIER                                                             R. Chen
Internet-Draft                                                     B. Xu
Intended status: Standards Track                                Z. Zhang
Expires: 21 July 2024                                    ZTE Corporation
                                                         18 January 2024


                       BGP extensions for BIER-TE
                   draft-chen-bier-idr-bier-te-bgp-02

Abstract

   Bit Index Explicit Replication (BIER)-TE shares architecture and
   packet formats with BIER as described in [RFC8279].  BIER-TE forwards
   and replicates packets based on a BitString in the packet header, but
   every BitPosition of the BitString of a BIER-TE packet indicates one
   or more adjacencies as described in [RFC8279].

   This document describes BGP extensions for advertising the BIER-TE
   specific information.

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
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   This Internet-Draft will expire on 21 July 2024.

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
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   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components



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   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
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  BIER-TE TLV . . . . . . . . . . . . . . . . . . . . . . . . .   2
     3.1.  The BIER MPLS Encapsulation sub-TLV . . . . . . . . . . .   3
     3.2.  The BIER non-MPLS Encapsulation sub-TLV . . . . . . . . .   4
     3.3.  The Bitposition sub-TLV . . . . . . . . . . . . . . . . .   4
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  The new BIER-TE TLVs  . . . . . . . . . . . . . . . . . .   5
     5.2.  The new BIER-TE Encapsulation sub-TLVs  . . . . . . . . .   6
     5.3.  The new Bitposition sub-TLV . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Bit Index Explicit Replication (BIER)-TE shares architecture and
   packet formats with BIER as described in [RFC8279].  BIER-TE forwards
   and replicates packets based on a BitString in the packet header, but
   every BitPosition of the BitString of a BIER-TE packet indicates one
   or more adjacencies as described in [RFC9262].

   This document describes BGP extensions for advertising the BIER-TE
   specific information.  More specifically, in this document, we define
   a new optional, non-transitive BGP attribute, referred to as the
   BIER-TE attribute, to convey the BIER-TE specific information.

   These extensions are applicable to BGP based network scenarios.

2.  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 RFC 2119 [RFC2119].

3.  BIER-TE TLV

   [I-D.ietf-bier-idr-extensions] defines BIER Path attribute, and this
   document reuse the Bier Path attribute.  The content of the BIER Path
   attribute is one or more BIER-TE TLV as shown in Figure 1.  This TLV
   contains BIER-TE information associated with a Prefix.



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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Type (TBD1)          |             Length            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | sub-domain-id |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  sub-TLVs (variable)                          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                Figure 1

   Type:A 2-octet field with value TBD1, see IANA Considerations
   section.

   Length: 2 octets.

   Subdomain-id: Unique value identifying the BIER-TE sub-domain, 1
   octet.

   Sub-TLVs: contains one or more sub-TLV.  In this document, it defines
   three sub-TLV: the BIER MPLS Encapsulation sub-TLV , the BIER non-
   MPLS Encapsulation sub-TLV and the Bitposition sub-TLV.

3.1.  The BIER MPLS Encapsulation sub-TLV

   This sub-TLV carries the information for the BIER MPLS encapsulation
   including the label range for a specific BitString length for a
   certain < MT,SD >.  It is advertised within the BIER-TE TLV.  This
   sub-TLV MAY appear multiple times within a single BIER-TE sub-TLV.
   If the same BitString length is repeated in multiple sub-TLVs inside
   the same BIER-TE TLV, the BIER-TE TLV MUST be ignored.

        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       |   Length      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Max SI      |BS Len |                    Label              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                               Figure 2

   Type:A 2-octet field with value TBD2.

   Length:4




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   Max SI: Maximum Set Identifier (Section 1 of [RFC8279]) used in the
   encapsulation for this BIER subdomain for this BitString length, 1
   octet.  Each SI maps to a single label in the label range.  The first
   label is for SI=0, the second label is for SI=1, etc.  If the label
   associated with the Maximum Set Identifier exceeds the 20-bit range,
   the sub-sub-TLV MUST be ignored.

   Local BitString Length (BS Len): Encoded BitString length as per
   [RFC8296]. 4 bits.

   Label: First label of the range, 20 bits.  The labels are as defined
   in [RFC8296].

3.2.  The BIER non-MPLS Encapsulation sub-TLV

   The sub-TLV is advertised within the BIER-TE TLV.

       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       |   Length      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Max SI      |BS Len |                  BIFT-id              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                                Figure 3

   Type:A 2-octet field with value TBD3.

   Length:4

   Max SI: Maximum Set Identifier (Section 1 of [RFC8279]) used in the
   encapsulation for this BIER subdomain for this BitString length, 1
   octet.  The first BIFT-id is for SI=0, the second BIFT-id is for
   SI=1, etc.  If the BIFT-id associated with the Maximum Set Identifier
   exceeds the 20-bit range, the sub-TLV MUST be ignored.

   Local BitString Length (BS Len): Encoded BitString length as per
   [RFC8296]. 4 bits.

   BIFT-id: A 20 bit field encoding the first BIFT-id of the BIFT-id
   range.  BIFT-id as per [I-D.ietf-bier-lsr-non-mpls-extensions].

3.3.  The Bitposition sub-TLV






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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Type                 |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           BitPosition-1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |                   Adjacency address-1                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          :                                                               :
      :                                                               :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |          BitPosition-n        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |                   Adjacency address-n                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                               Figure 4

   Type:A 2-octet field with value TBD4.

   Length:4 if the Nexthop is IPv4 address and 16 if the Nexthop is IPv6
   address

   <BitPosition,Adjacency address>: A 2-octet field encoding the
   BitPosition associated with a adjacency address.  Each adjacency
   address is a local or remote neighbor address.

   The Bitposition sub-TLV is included in the BIER-TE TLV.

4.  Acknowledgements

   The authors would like to thank Zhaohui Zhang for his valuable
   suggestions.

5.  IANA Considerations

   The document requests new allocations from the IANA registries as
   follows:

5.1.  The new BIER-TE TLVs

   This document requests assigning code-points from the "BGP BIER Path
   Attribute Types" registry for the new BIER-TE TLV.







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           +-------------------+-----------------------------+-----------------+
           |   TLV Code Point  |  Description                | Value defined   |
           +-------------------+-----------------------------+-----------------+
           |       TBD1        | BIER-TE                     | this document   |
           +-------------------+-----------------------------+-----------------+

                               Figure 5

5.2.  The new BIER-TE Encapsulation sub-TLVs

   This document requests assigning code-points from the "BGP BIER-TE
   TLV sub-TLV Types" for the new BIER-TE Encapsulation sub-TLVs.


           +----------------------+-----------------------------+-----------------+
           |  Sub-TLV Code Point  |  Description                | Value defined   |
                   +----------------------+-----------------------------+-----------------+
           |       TBD2           | BIER MPLS Encapsulation     | this document   |
           +----------------------+-----------------------------+-----------------+
           |       TBD3           | BIER non-MPLS Encapsulation | this document   |
           +----------------------+-----------------------------+-----------------+

                               Figure 6

5.3.  The new Bitposition sub-TLV

   This document requests assigning code-points from the "BGP BIER-TE
   TLV sub-TLV Types" for the new Bitposition sub-TLV.


           +----------------------+-----------------------------+-----------------+
           |  Sub-TLV Code Point  |  Description                | Value defined   |
                   +----------------------+-----------------------------+-----------------+
           |       TBD4           | Bitposition sub-TLV         | this document   |
           +----------------------+-----------------------------+-----------------+


                               Figure 7

6.  Security Considerations

   TBD.

7.  Normative References

   [I-D.ietf-bier-idr-extensions]
              Xu, X., Chen, M., Patel, K., Wijnands, I., Przygienda, T.,
              and Z. J. Zhang, "BGP Extensions for BIER", Work in



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              Progress, Internet-Draft, draft-ietf-bier-idr-extensions-
              10, 13 June 2023, <https://datatracker.ietf.org/doc/html/
              draft-ietf-bier-idr-extensions-10>.

   [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-01, 19 September 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bier-
              lsr-non-mpls-extensions-01>.

   [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>.

   [RFC4915]  Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
              Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
              RFC 4915, DOI 10.17487/RFC4915, June 2007,
              <https://www.rfc-editor.org/info/rfc4915>.

   [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>.

   [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>.

   [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>.

Authors' Addresses

   Ran Chen
   ZTE Corporation
   Nanjing
   China
   Email: chen.ran@zte.com.cn





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


   Zheng Zhang
   ZTE Corporation
   Nanjing
   China
   Email: zhang.zheng@zte.com.cn







































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