Internet DRAFT - draft-zwx-bier-te-isis-extensions

draft-zwx-bier-te-isis-extensions







BIER                                                            Z. Zhang
Internet-Draft                                                    Y. Wei
Intended status: Standards Track                                   B. Xu
Expires: 25 January 2023                                 ZTE Corporation
                                                            24 July 2022


 IS-IS extensions for BIER-TE (Tree Engineering for Bit Index Explicit
           Replication) with MPLS and non-MPLS Encapsulation
                  draft-zwx-bier-te-isis-extensions-01

Abstract

   This document describes the IS-IS protocol extension that is required
   for BIER-TE with MPLS and non-MPLS encapsulation.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 25 January 2023.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Flooding of the BIER-TE Encapsulation Information in IS-IS  .   3
     3.1.  MPLS Encapsulation Sub-sub-TLV  . . . . . . . . . . . . .   3
     3.2.  Non-MPLS Encapsulation Sub-sub-TLV  . . . . . . . . . . .   4
       3.2.1.  BIER-TE IPv6 Encapsulation Advertisement  . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   [I-D.ietf-bier-te-arch] describes per-packet stateless strict and
   loose path steered replication and forwarding for "Bit Index Explicit
   Replication" (BIER, [RFC8279]) packets.  It is called BIER Tree
   Engineering (BIER-TE) and is intended to be used as the path steering
   mechanism for Traffic Engineering with BIER.

   BIER-TE introduces a new semantic for "bit positions" (BP) of link.
   [I-D.ietf-bier-te-isis] describes IS-IS extensions for distributing
   BitPositions configured on the links in "Bit Index Explicit
   Replication Traffic Engineering" (BIER-TE) domain.

   As described in section 2.3 in [I-D.ietf-bier-te-arch], BIER-TE
   inherits the encapsulation supporting from BIER unchanged.  The
   encapsulation defined in [RFC8296], which specifies a common header
   format for both MPLS and non-MPLS networks, though the first 20-bits
   (referred to as BIFT-id) of the header is an "MPLS Label" in case of
   MPLS networks and is a local 20-bit opaque value in case of non-MPLS
   networks.

   As described in section 4.3 of [I-D.ietf-bier-te-arch], it is
   necessary to distinguish the BIER and BIER-TE packet and forwarding.
   like [RFC8401] and [I-D.ietf-bier-lsr-non-mpls-extensions], the MPLS
   and non-MPLS encapsulation needs to be advertised for BIER-TE packet
   encapsulation.

   This document describes the IS-IS protocol extension that is required
   for BIER-TE with MPLS and non-MPLS encapsulation associated with link
   BitPosition distributing.






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1.1.  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].

2.  Terminology

   This document does not introduce more terminologies than [RFC8279],
   [RFC8296], [RFC8401], [I-D.ietf-bier-te-arch] and
   [I-D.ietf-bier-te-isis].

3.  Flooding of the BIER-TE Encapsulation Information in IS-IS

   [I-D.ietf-bier-te-isis] defines a BIER-TE Info Sub-TLV to distribute
   the Link BitPosition information about the link.  This document
   defines the MPLS Encapsulation Sub-sub-TLV and the Non-MPLS
   Encapsulation Sub-sub-TLV associate with the BIER-TE Sub-TLV to carry
   the MPLS and non-MPLS encapsulation information.

   In case both of the two encapsulation sub-sub-TLVs are advertised by
   one node, the label in MPLS encapsulation sub-sub-TLV and BIFT-id in
   non-MPLS encapsulation sub-sub-TLV SHOULD NOT be overlapped.

3.1.  MPLS Encapsulation Sub-sub-TLV

   The following description is the almost same with [RFC8401] since
   [I-D.ietf-bier-te-arch] inherit the encapsulation of BIER header.

      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    |                     Label                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |BS Len |                     Reserved                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                  Figure 1

   Type: TBD1 (To be assigned by IANA).

   Length: 2-octet.

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



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   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 (BitString Length): A 4-bit field encoding the supported
   BitString length associated with this BFR-prefix.  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.

   The "label range" is the set of labels beginning with the Label and
   ending with (Label + (Max SI)).  A unique label range is allocated
   for each BitString length and sub-domain-id.

   The size of the label range is determined by the number of SIs
   (Section 1 of [RFC8279]) that are used in the network.  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 BIER MPLS Encapsulation Sub-TLV containing the
   error MUST be ignored.

   If the BitString length is set to a value that does not match any of
   the allowed values specified in [RFC8296], the BIER MPLS
   Encapsulation Sub-TLV containing the error MUST be ignored.

   The "BIFT-id range" is the set of 20-bit values beginning with the
   BIFT-id and ending with (BIFT-id + (Max SI)).

   The flooding scope of this information is the same with section 5 in
   [RFC8401].

3.2.  Non-MPLS Encapsulation Sub-sub-TLV

   The following description is the almost same with section 3.1 in
   [I-D.ietf-bier-lsr-non-mpls-extensions] since [I-D.ietf-bier-te-arch]
   inherit the encapsulation of BIER header.












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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    |                   BIFT-id                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |BS Len |                     Reserved                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                  Figure 2

   Type: TBD2 (To be assigned by IANA).

   Length: 2-octet.

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

   BIFT-id: 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 (BitString Length): A 4-bit field encoding the supported
   BitString length associated with this BFR-prefix.  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.

   The BIFT-id range, limitation and flooding scope is the same with the
   MPLS encapsulation sub-sub-TLV.

3.2.1.  BIER-TE IPv6 Encapsulation Advertisement

   As described in section 4 of [I-D.ietf-bier-bierin6], which describes
   how the existing BIER encapsulation specified in [RFC8296] works in a
   non-MPLS IPv6 network, a node that requires IPv6 encapsulation MUST
   advertise the BIER-TE IPv6 encapsulation sub-sub-sub-TLV, which
   follows the Non-MPLS Encapsulation Sub-sub-TLV, according to local
   configuration or policy in the BIER domain to request other BFRs to
   always use IPv6 encapsulation.








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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      |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3

   Type: TBD3 (To be assigned by IANA).

   Length: 0.

4.  IANA Considerations

   TBD.

5.  Security Considerations

   This document does not introduce more security considerations than
   [I-D.ietf-bier-te-arch] and [I-D.ietf-bier-te-isis].

6.  References

6.1.  Normative References

   [I-D.ietf-bier-bierin6]
              Zhang, Z., Zhang, Z., Wijnands, I., Mishra, M., Bidgoli,
              H., and G. Mishra, "Supporting BIER in IPv6 Networks
              (BIERin6)", Work in Progress, Internet-Draft, draft-ietf-
              bier-bierin6-04, March 2022,
              <https://www.ietf.org/archive/id/draft-ietf-bier-
              bierin6-04.txt>.

   [I-D.ietf-bier-lsr-non-mpls-extensions]
              Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang,
              Z., and J. Xie, "LSR Extensions for BIER non-MPLS
              Encapsulation", Work in Progress, Internet-Draft, draft-
              ietf-bier-lsr-non-mpls-extensions-00, March 2022,
              <https://www.ietf.org/archive/id/draft-ietf-bier-lsr-non-
              mpls-extensions-00.txt>.

   [I-D.ietf-bier-te-arch]
              Eckert, T., Menth, M., and G. Cauchie, "Tree Engineering
              for Bit Index Explicit Replication (BIER-TE)", Work in
              Progress, Internet-Draft, draft-ietf-bier-te-arch-13, 25
              April 2022, <https://www.ietf.org/archive/id/draft-ietf-
              bier-te-arch-13.txt>.




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   [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-00,
              25 January 2022, <https://www.ietf.org/archive/id/draft-
              ietf-bier-te-isis-00.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>.

   [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", DOI 10.17487/RFC8401, RFC 8401, June 2018,
              <https://www.rfc-editor.org/info/rfc8401>.

Authors' Addresses

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


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


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




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