Internet DRAFT - draft-cz-bier-bgp-ls-bier-te-ext

draft-cz-bier-bgp-ls-bier-te-ext







BIER                                                             R. Chen
Internet-Draft                                                  Z. Zhang
Intended status: Standards Track                         ZTE Corporation
Expires: 22 April 2024                                            Y. Liu
                                                            China Mobile
                                                            L. Changwang
                                                    New H3C Technologies
                                                         20 October 2023


                     BGP-LS extensions for BIER-TE
                  draft-cz-bier-bgp-ls-bier-te-ext-03

Abstract

   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.

   BGP Link-State (BGP-LS) enables the collection of various topology
   informations from the network, and the topology informations are used
   by the PCE to calculate the path and then propagate them onto the
   BFRs(instead of having each node to calculate on its own) and that
   can be for both inter-as and intra-as situations.

   This document specifies extensions to the BGP Link-state address-
   family in order to advertise BIER-TE informations.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 22 April 2024.







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Copyright Notice

   Copyright (c) 2023 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.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  BGP-LS Extensions for BIER-TE . . . . . . . . . . . . . . . .   3
     2.1.  The BIER-TE information TLV . . . . . . . . . . . . . . .   3
     2.2.  The MPLS Encapsulation TLV  . . . . . . . . . . . . . . .   4
     2.3.  The non-MPLS Encapsulation TLV  . . . . . . . . . . . . .   5
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   7.  Informative references  . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

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].

   When BIER-TE is enabled in an IGP domain, BIER-TE-related
   informations will be advertised via IGP link-state routing protocols.
   The flooding scope for the IGP extensions for BIER-TE is IGP area-
   wide. by using the IGP alone it is not enough to construct across
   multiple IGP Area.

   The BGP-LS address-family/sub-address-family have been defined to
   allow BGP to carry Link-State informations.  This document specifies
   extensions to the BGP Link-state address-family in order to advertise
   BIER-TE-specific informations, Similar to BGP-LS Advertisement of IGP
   Traffic Engineering Performance Metric Extensions([RFC8571]).  An



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   external component (e.g., a controller/a PCE(see [RFC4655] for PCE-
   Based Architecture , [RFC5440] for PCEP and [RFC5376] for Inter-AS
   Requirements for the PCEP.))then can learn the BIER-TE informations
   in the "northbound" direction and calculate BIER-TE Path and then
   propagate them onto BFRs (instead of having each BFR to calculate on
   its own), and that can be for both inter-as and intra-as situations.

1.1.  Requirements Language

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

2.  BGP-LS Extensions for BIER-TE

   BIER-TE attributes and BitPositions associated with a link or
   adjacency are advertised using the BGP-LS link Attribute TLVs defined
   in this section and associated with the BGP-LS Link NLRI.

   Given that the BIER-TE informations are associated with the link or
   adjacency , the link Attribute TLV [RFC7752] can be used to carry the
   BIER-TE informations.  The new Prefix Attribute TLVs are defined for
   the encoding of BIER-TE informations.

2.1.  The BIER-TE information TLV

   The BIER-TE information TLV is defined to advertise the BIER-TE
   informations.  The informations are derived from BIER-TE Info Sub-TLV
   of IS-IS (section 2 of [I-D.ietf-bier-te-isis]) BIER-TE sub-TLV of
   OSPFv2 (section 2 of [I-D.ietf-bier-te-ospf]) and OSPFv3 (section 2
   of [I-D.ietf-bier-te-ospfv3]).  According to different subdomain, the
   BIER-TE information TLV may appear multiple times.

   The following BIER-TE information TLV is defined:


     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 (TBD )          |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | sub-domain-id |       BAR     |    IPA        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         BitPosition           |           EndBitPosition      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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                                  Figure 1

   Type: TBD, see IANA Considerations section.

   Length: 2 octets.

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

   BAR: A 1-octet field encoding the BIER Algorithm, used to calculate
   underlay paths to reach BFERs.  Values are allocated from the "BIER
   Algorithms" registry which is defined in [RFC8401].

   IPA: A 1-octet field encoding the IGP Algorithm, used to either
   modify,enhance, or replace the calculation of underlay paths to reach
   BFERs as defined by the BAR value.  Values are from the IGP Algorithm
   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).

   EndBitPosition: A 2-octet field encoding the BitPosition of the
   connection on the designated Intermediate Systems (Dis) end (ISIS) /
   designated router (DR) end( OSPFv2 and OSPFv3), as defined in section
   2 of [I-D.ietf-bier-te-isis] , section 2 of [I-D.ietf-bier-te-ospf]
   and [I-D.ietf-bier-te-ospfv3].

2.2.  The MPLS Encapsulation TLV

   The MPLS Encapsulation TLV is used in order to advertise MPLS
   specific informations used for BIER-TE.  It MAY appear multiple
   times.  The informations are derived from MPLS Encapsulation Sub-sub-
   TLV of IS-IS(section 3.1 of [I-D.zwx-bier-te-extensions]), MPLS
   Encapsulation Sub-sub-TLV of OSPFv2 and OSPFv3(section 4.1 of
   [I-D.zwx-bier-te-extensions]).

   In some environment, each router allocates its labels, and advertises
   it to the controller.That solution is simpler as the controller does
   not need to deal with label allocation.  If the controller has to
   deal with Label allocation , there needs to be a (global) range
   carved out such there are no conflicts.  We can avoid all that by
   having the router allocate the BIER Label range and advertise it to
   the controller.

   The following the MPLS Encapsulation TLV is defined:



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

                                  Figure 2

   Type: TBD, see IANA Considerations section.

   Length: 4.

   Max SI: A 1-octet field encoding the maximum Set Identifier(as
   defined in [RFC8279]), used in the encapsulation for this BIER
   subdomain for this BitString length.

   BS Len: A 4-bit field field encoding the Bitstring length as per
   [RFC8296].

   Label: First label of the range, 20 bits.  The labels are as defined
   [RFC8296].  The 4 leftmost bits MUST be ignored.

   BS length in multiple MPLS Encapsulation TLV associated with the same
   BIER-TE information TLV MUST NOT repeat, otherwise only the first
   MPLS Encapsulation TLV with such BS length MUST be used and any
   subsequent MPLS Encapsulation TLVs with the same BS length MUST be
   ignored.

2.3.  The non-MPLS Encapsulation TLV

   The non-MPLS Encapsulation TLV is used in order to advertise non-MPLS
   encapsulation(e.g. ethernet encapsulation ) capability and other
   associated parameters of the encapsulation.  It MAY appear multiple
   times.  The informations are derived from non-MPLS Encapsulation Sub-
   sub-TLV of IS-IS(section 3.2 of [I-D.zwx-bier-te-extensions]), non-
   MPLS Encapsulation Sub-sub-TLV of OSPFv2 and OSPFv3 (section 4.2 of
   [I-D.zwx-bier-te-extensions]).

   The following the non-MPLS Encapsulation TLV is defined:










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

                                  Figure 3

   Type: TBD, see IANA Considerations section.

   Length: 4.

   Max SI:A 1-octet field encoding the maximum Set Identifier(as defined
   in [RFC8279]), used in the encapsulation for this BIER subdomain for
   this BitString length.

   The "BIFT-id range" is the set of 20-bit values beginning with the
   BIFT-id and ending with (BIFT-id + (Max SI)).  A unique BIFT-id range
   is allocated for each BitString length and sub-domain-id.  These
   BIFT-id's are used for BIER forwarding as described in [RFC8279])and
   [RFC8296].

   Local BitString Length (BS Len): A 4-bit field encoding the Bitstring
   length as per [RFC8296].

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

3.  IANA Considerations

   This document requests assigning code-points from the registry for
   the new link Attribute TLVs.

        +================+========================+===============+
        | TLV Code Point |      Description       | Value defined |
        +================+========================+===============+
        |      TBD1      |  BIER-TE information   | this document |
        +----------------+------------------------+---------------+
        |      TBD2      |   MPLS Encapsulation   | this document |
        +----------------+------------------------+---------------+
        |      TBD3      | non-MPLS Encapsulation | this document |
        +----------------+------------------------+---------------+

                    Table 1: The new link Attribute TLVs




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4.  Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the BGP security model.  See the "Security
   Considerations"section of [RFC4271] for a discussion of BGP security.
   Security considerations for acquiring and distributing BGP-LS
   information are discussed in [RFC7752].

5.  Acknowledgements

   TBD.

6.  Normative References

   [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>.

   [I-D.ietf-bier-te-isis]
              Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y.,
              Liu, L., and X. Liu, "IS-IS Extensions for BIER-TE", Work
              in Progress, Internet-Draft, draft-ietf-bier-te-isis-08, 6
              July 2023, <https://datatracker.ietf.org/doc/html/draft-
              ietf-bier-te-isis-08>.

   [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/doc/html/draft-
              ietf-bier-te-ospf-06>.

   [I-D.ietf-bier-te-ospfv3]
              Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y.,
              Liu, L., and X. Liu, "OSPFv3 Extensions for BIER-TE", Work
              in Progress, Internet-Draft, draft-ietf-bier-te-ospfv3-06,
              5 July 2023, <https://datatracker.ietf.org/doc/html/draft-
              ietf-bier-te-ospfv3-06>.

   [I-D.zwx-bier-te-extensions]
              Zhang, Z., Wei, Y., Xu, B., and I. Wijnands, "IS-IS and
              OSPF extensions for BIER-TE (Tree Engineering for Bit
              Index Explicit Replication) with MPLS and non-MPLS
              Encapsulation", Work in Progress, Internet-Draft, draft-



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              zwx-bier-te-extensions-03, 3 September 2023,
              <https://datatracker.ietf.org/doc/html/draft-zwx-bier-te-
              extensions-03>.

   [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>.

   [RFC4655]  Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
              Computation Element (PCE)-Based Architecture", RFC 4655,
              DOI 10.17487/RFC4655, August 2006,
              <https://www.rfc-editor.org/info/rfc4655>.

   [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>.

   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
              S. Ray, "North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP", RFC 7752,
              DOI 10.17487/RFC7752, March 2016,
              <https://www.rfc-editor.org/info/rfc7752>.

   [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>.

   [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>.






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   [RFC8571]  Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and
              C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of
              IGP Traffic Engineering Performance Metric Extensions",
              RFC 8571, DOI 10.17487/RFC8571, March 2019,
              <https://www.rfc-editor.org/info/rfc8571>.

   [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>.

7.  Informative references

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC5376]  Bitar, N., Zhang, R., and K. Kumaki, "Inter-AS
              Requirements for the Path Computation Element
              Communication Protocol (PCECP)", RFC 5376,
              DOI 10.17487/RFC5376, November 2008,
              <https://www.rfc-editor.org/info/rfc5376>.

   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,
              <https://www.rfc-editor.org/info/rfc5440>.

Authors' Addresses

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


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








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   Yisong Liu
   China Mobile
   Beijing
   China
   Email: liuyisong@chinamobile.com


   Changwang Lin
   New H3C Technologies
   Beijing
   China
   Email: linchangwang.04414@h3c.com







































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