BIER                                                         S. Dhanaraj
Internet-Draft                                                    G. Yan
Updates: 8296 (if approved)                                       Huawei
Intended status: Standards Track                             I. Wijnands
Expires: 2 September 2022                                     Individual
                                                               P. Psenak
                                                     Cisco Systems, Inc.
                                                           Z. Zhang, Ed.
                                                       Juniper Networks.
                                                                  J. Xie
                                                                  Huawei
                                                            1 March 2022


             LSR Extensions for BIER non-MPLS Encapsulation
               draft-ietf-bier-lsr-non-mpls-extensions-00

Abstract

   Bit Index Explicit Replication (BIER) is an architecture that
   provides multicast forwarding through a "BIER domain" without
   requiring intermediate routers to maintain multicast related per-flow
   state.  BIER can be supported in MPLS and non-MPLS networks.

   This document specifies the required extensions to the IS-IS, OSPFv2
   and OSPFv3 protocols for supporting BIER in non-MPLS networks using
   BIER non-MPLS encapsulation.

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 2 September 2022.







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Copyright Notice

   Copyright (c) 2022 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
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   4
   3.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  IS-IS BIER non-MPLS Encapsulation Sub-sub TLV . . . . . .   5
     3.2.  OSPFv2 BIER non-MPLS Encapsulation Sub-TLV  . . . . . . .   6
     3.3.  OSPFv3 BIER non-MPLS Encapsulation Sub-TLV  . . . . . . .   8
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     5.1.  IS-IS sub-sub-TLVs for BIER Info sub-TLV Registry . . . .  10
     5.2.  OSPFv2 Extended Prefix TLV Sub-TLVs Registry  . . . . . .  10
     5.3.  OSPFv3 Extended LSA Sub-TLVs Registry . . . . . . . . . .  10
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
   that provides multicast forwarding through a "BIER domain" without
   requiring intermediate routers to maintain multicast related per-flow
   state.  BIER specific forwarding state, while not per-flow, are
   maintained in Bit Index Forwarding Tables (BIFTs) and used to forward
   BIER-encapsulated packets.










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   BIER can be supported in MPLS and non-MPLS networks.  [RFC8296]
   specifies a common BIER header format for both MPLS and non-MPLS
   networks, though the first 20-bits (referred to as BIFT-id) of the
   BIER header is an "MPLS Label" in case of MPLS networks and is a
   "domain-wide unique value" in case of non-MPLS networks.  It
   identifies the BIFT used to forwarding the packet.
   [I-D.ietf-bier-non-mpls-bift-encoding] specifies two optional ways of
   statically assigning domain-wide unique BIFT-id's.

   However, BIER architecture [RFC8279] does not require domain-wide-
   unique BIFT-id's to be used (even for non-MPLS encapsulation).  As
   discussed in [I-D.zzhang-bier-rift], the BIFT-id in case of non-MPLS
   encapsulation can also just be a local 20-bit opaque value and
   signaled just like in MPLS case.

   As an example, suppose a particular BIER domain contains a Sub-Domain
   (SD) 0, supports two BitStringLengths (BSLs - 256 and 512), and
   contains 1024 BIER Forwarding Egress Routers (BFERs).  Because the
   number of BFERs is larger than the BSL, the BFERs are grouped into
   different sets, and multiple copies of a packet may need to be sent
   by an BIER Forwarding Ingress Router (BFIR) - one for each set.  Each
   set has a Set Identifier (SI), and one BIFT is needed for each <SD,
   BSL, SI>.  A BIER Forwarding Router (BFR) that is provisioned for the
   above SD, and that supports both BSLs, could advertise the following
   set of BIFT-id's:

      BIFT-id 1: corresponding to SD 0, BSL 256, SI 0.

      BIFT-id 2: corresponding to SD 0, BSL 256, SI 1.

      BIFT-id 3: corresponding to SD 0, BSL 256, SI 2.

      BIFT-id 4: corresponding to SD 0, BSL 256, SI 3.

      BIFT-id 5: corresponding to SD 0, BSL 512, SI 0.

      BIFT-id 6: corresponding to SD 0, BSL 512, SI 1.

   Notice that the example uses ranges of continuous BIFT-id's:

      BIFT-id range [1 to 4] correspond to <SD 0, BSL 256>.  The first
      BIFT-id in the range correspond to SI=0, the second correspond to
      SI=1, and so on.

      BIFT-id range [5 to 6] correspond to <SD 0, BSL 512>.  The first
      BIFT-id in the range correspond to SI=0, the second correspond to
      SI=1.




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   Strictly speaking, using contiguous range is not required, but it is
   done for the purpose of simplified signaling similar to MPLS label
   blocks (notice that locally assigning BIFT-id ranges requires no
   manual processing just like in the case of MPLS label block
   allocation).

   Processing and forwarding of BIER packets requires special software
   and hardware capabilities.  The BFRs supporting a BIER encapsulation
   type MUST advertise this capability along with the required
   parameters specific to the encapsulation to the other routers in BIER
   domain.  This advertisements are used by other BFRs to calculate the
   BIFTs for a specific encapsulation type.

   [RFC8401], [RFC8444] and [I-D.ietf-bier-ospfv3-extensions] specifies
   the required extensions to the IS-IS [RFC1195], OSPFv2 [RFC2328] and
   OSPFv3 [RFC8362] protocols respectively for the distribution of BIER
   sub-domain information including the Sub-sub-TLVs required to support
   BIER in MPLS encapsulation for MPLS networks.

   This document specifies the required similar extensions to the IS-IS
   [RFC1195], OSPFv2 [RFC2328] and OSPFv3 [RFC8362] protocols for
   supporting BIER non-MPLS encapsulation with dynamically and locally
   assigned BIFT-id's.

2.  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.

3.  Specification

   This document updates section 2.2.1.1 of [RFC8296] that the BIFT-id
   in case of non-MPLS encapsulation need not be unique throughout the
   BIER domain and can change as the packet travels.

   A BIER sub-domain MAY use both MPLS and non-MPLS BIER encapsulation.
   The assignment of BFR-id in a sub-domain is independent of the
   encapsulation type.  This allows this same bit string to be used
   regardless of the encapsulation types used to reach BFERs.

   When a BFIR/BFR supports multiple BIER encapsulation types, when
   sending to a BIER neighbor it MUST use a type that the neighbor also
   supports.  If the neighbor also supports more than one encapsulation
   type that this BFIR/BFR supports, the type selection could be a
   matter of local policy and is outside the scope of this document.



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   The procedures in [RFC8401] and [RFC8444] apply to non-MPLS
   encapsulation, except the encoding and procedure differences
   specified below.

3.1.  IS-IS BIER non-MPLS Encapsulation Sub-sub TLV

   As specified in [RFC8401] and updated in [I-D.ietf-bier-bar-ipa],
   BIER Info sub-TLV is used to advertise BIER information except that
   its MPLS Encapsulation sub-sub-TLV is replaced with a new non-MPLS
   Encapsulation sub-sub-TLV specified as following.

   The BIER Info sub-TLV is carried within the TLVs 235, 237 [RFC5120]
   or TLVs 135 [RFC5305], or TLV 236 [RFC5308].  Its non-MPLS
   Encapsulation sub-sub-TLV carries the information for the BIER non-
   MPLS encapsulation and is very similar to the MPLS Encapsulation sub-
   sub-TLV.

   When a prefix reachability advertisement is leaked between levels, if
   it has a BIER sub-TLV with non-zero BFR-id the BIER sub-TLV MUST be
   included but its non-MPLS Encapsulation sub-sub-TLV MAY be omitted.

   The non-MPLS Encapsulation sub-sub-TLV MAY appear multiple times
   within a single BIER Info sub-TLV.  If the same BitString length is
   repeated in multiple BIER non-MPLS encapsulation sub-sub-TLVs inside
   the same BIER Info sub-TLV, the BIER Info sub-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 |                  BIFT-id              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:  TBD1 (To be assigned by IANA).


   Length:  4


   Max SI:  A 1 octet field encoding the Maximum Set Identifier
    (Section 1 of [RFC8279]) used in the encapsulation for this BIER
    subdomain for this BitString length.  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-sub-TLV
    MUST be ignored.

   Local BitString Length (BS Len):  A 4 bit field encoding the



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    bitstring length (as per [RFC8296]) supported for the encapsulation.

   BIFT-id:  A 20 bit field encoding the first BIFT-id of the BIFT-id
    range.
     The "BIFT-id range" is the set of 20-bit values beginning with the
    BIFT-id and ending with (BIFT-id + (Max SI)).  These BIFT-id's are
    used for BIER forwarding as described in [RFC8279] and [RFC8296].
     The size of the BIFT-id range is determined by the number of SI's
    (Section 1 of [RFC8279]) that are used in the network.  Each SI maps
    to a single BIFT-id in the BIFT-id range: 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 BIER non-MPLS Encapsulation Sub-sub-TLV
    containing the error MUST be ignored.
     BIFT-id ranges within all the BIER non-MPLS Encapsulation sub-sub-
    TLVs advertised by the same BFR MUST NOT overlap.  If the overlap is
    detected, the advertising router MUST be treated as if it did not
    advertise any BIER non-MPLS encapsulation sub-sub-TLVs.  However the
    BIFT-id ranges may overlap across different encapsulation types and
    is allowed.  As an example, the BIFT-id value in the non-MPLS
    encapsulation sub-sub-TLV may overlap with the Label value in the
    Label range in BIER MPLS encapsulation sub-sub-TLV ([RFC8401] and is
    allowed.

3.2.  OSPFv2 BIER non-MPLS Encapsulation Sub-TLV

   As specified in [RFC8444] and updated in [I-D.ietf-bier-bar-ipa],
   BIER Sub-TLV is used to advertise BIER information except that its
   MPLS Encapsulation sub-TLV is replaced with a new non-MPLS
   Encapsulation sub-TLV specified as following.

   The BIER sub-TLV [RFC8444] is carried within the OSPFv2 Extended
   Prefix TLV [RFC7684].  Its non-MPLS Encapsulation sub-TLV carries
   information for the BIER non-MPLS encapsulation, and is very similar
   to MPLS Encapsulation sub-TLV.

   When a prefix reachability is re-advertised into other areas, if it
   has a BIER sub-TLVs with a non-zero BFR-id the BIER sub-TLV MUST be
   included but its non-MPLS Encapsulation sub-TLV MAY be omitted.

   The non-MPLS Encapsulation Sub-TLV MAY appear multiple times within a
   single BIER Sub-TLV.  If the same BitString length is repeated in
   multiple BIER non-MPLS encapsulation Sub-TLVs inside the same BIER
   Sub-TLV, the BIER Sub-TLV MUST be ignored.







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

   Type:  TBD2 (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
    subdomain for this BitString length.  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-sub-TLV
    MUST be ignored.

   BIFT-id:  A 3-octet field, where the 20 rightmost bits represent the
    first BIFT-id in the BIFT-id range.  The 4 leftmost bits 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)).  These BIFT-id's are
    used for BIER forwarding as described in [RFC8279] and [RFC8296].
     The size of the BIFT-id range is determined by the number of SI's
    (Section 1 of [RFC8279]) that are used in the network.  Each SI maps
    to a single BIFT-id in the BIFT-id range: 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 BIER non-MPLS Encapsulation Sub-sub-TLV
    containing the error MUST be ignored.
     BIFT-id ranges within all the BIER non-MPLS Encapsulation sub-sub-
    TLVs advertised by the same BFR MUST NOT overlap.  If the overlap is
    detected, the advertising router MUST be treated as if it did not
    advertise any BIER non-MPLS encapsulation sub-sub-TLVs.  However the
    BIFT-id ranges may overlap across different encapsulation types and
    is allowed.  As an example, the BIFT-id value in the non-MPLS
    encapsulation sub-sub-TLV may overlap with the Label value in the
    Label range in BIER MPLS encapsulation sub-sub-TLV ([RFC8444] and is
    allowed.

   Local BitString Length (BS Len):  A 4 bit field encoding the
    bitstring length (as per [RFC8296]) supported for the encapsulation.



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

3.3.  OSPFv3 BIER non-MPLS Encapsulation Sub-TLV

   As specified in [I-D.ietf-bier-ospfv3-extensions], BIER Sub-TLV is
   used to advertise BIER information except that its MPLS Encapsulation
   sub-TLV is replaced with a new non-MPLS encapsulation sub-TLV
   specified as following.

   The BIER Sub-TLV is carried within the Intra-Area-Prefix TLV or
   Inter-Area-Prefix TLV in OSPFv3 Extended LSA TLV defined in
   [RFC8362].  its non-MPLS Encapsulation Sub-TLV carries information
   for the BIER non-MPLS encapsulation, and is very similar to the MPLS
   Encapsulation sub-TLV.

   When a prefix reachability is re-advertised into other areas, if it
   has a BIER sub-TLVs with a non-zero BFR-id the BIER sub-TLV MUST be
   included but its non-MPLS Encapsulation sub-TLV MAY be omitted.

   The non-MPLS Encapsulation Sub-TLV MAY appear multiple times within a
   single BIER Sub-TLV.  If the same BitString length is repeated in
   multiple BIER non-MPLS encapsulation Sub-TLVs inside the same BIER
   Sub-TLV, the BIER Sub-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    |                   BIFT-id                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |BS Len |                     Reserved                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:  TBD3 (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
    subdomain for this BitString length.  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-sub-TLV
    MUST be ignored.




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   BIFT-id:  A 3-octet field, where the 20 rightmost bits represent the
    first BIFT-id in the BIFT-id range.  The 4 leftmost bits 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)).  These BIFT-id's are
    used for BIER forwarding as described in [RFC8279] and [RFC8296].
     The size of the BIFT-id range is determined by the number of SI's
    (Section 1 of [RFC8279]) that are used in the network.  Each SI maps
    to a single BIFT-id in the BIFT-id range: 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 BIER non-MPLS Encapsulation Sub-sub-TLV
    containing the error MUST be ignored.
     BIFT-id ranges within all the BIER non-MPLS Encapsulation sub-sub-
    TLVs advertised by the same BFR MUST NOT overlap.  If the overlap is
    detected, the advertising router MUST be treated as if it did not
    advertise any BIER non-MPLS encapsulation sub-sub-TLVs.  However the
    BIFT-id ranges may overlap across different encapsulation types and
    is allowed.  As an example, the BIFT-id value in the non-MPLS
    encapsulation sub-sub-TLV may overlap with the Label value in the
    Label range in BIER MPLS encapsulation sub-sub-TLV
    ([I-D.ietf-bier-non-mpls-bift-encoding] and is allowed.

   Local BitString Length (BS Len):  A 4 bit field encoding the
    bitstring length (as per [RFC8296]) supported for the encapsulation.

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

4.  Security Considerations

   Security concerns for IS-IS are addressed in [RFC5304] and [RFC5310]
   and the security concerns for IS-IS extensions for BIER are addressed
   in [RFC8401].  This document introduces new sub-sub-TLV for the
   already existing IS-IS TLVs defined for distributing the BIER sub-
   domain information in [RFC8401].  It does not introduce any new
   security risks to IS-IS.

   Security concerns and required extensions for OSPFv2 are addressed in
   [RFC2328] and [RFC7684] and the security concerns for OSPFv2
   extensions for BIER are addressed in [RFC8444].  This document
   introduces new Sub-TLV for the already existing OSPFv2 TLV defined
   for distributing the BIER sub-domain information in [RFC8444].  It
   does not introduce any new security risks to OSPFv2.







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5.  IANA Considerations

   The document requests new allocations from the IANA registries as
   follows

5.1.  IS-IS sub-sub-TLVs for BIER Info sub-TLV Registry

      BIER non-MPLS Encapsulation sub-sub-TLV: TBD1 (suggested value 2)

5.2.  OSPFv2 Extended Prefix TLV Sub-TLVs Registry

      BIER non-MPLS Encapsulation Sub-TLV: TBD2 (suggested value 11)

5.3.  OSPFv3 Extended LSA Sub-TLVs Registry

      BIER non-MPLS Encapsulation Sub-TLV: TBD3 (suggested value 11)

6.  Acknowledgments

   The author wants to thank Antonie Przygienda for his comments and
   suggestions.

7.  References

7.1.  Normative References

   [I-D.ietf-bier-bar-ipa]
              Zhang, Z., Przygienda, A., Dolganow, A., Bidgoli, H.,
              Wijnands, I., and A. Gulko, "BIER Underlay Path
              Calculation Algorithm and Constraints", Work in Progress,
              Internet-Draft, draft-ietf-bier-bar-ipa-10, 1 February
              2022, <https://www.ietf.org/archive/id/draft-ietf-bier-
              bar-ipa-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>.

   [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>.







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   [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>.

7.2.  Informative References

   [I-D.ietf-bier-non-mpls-bift-encoding]
              Wijnands, I., Mishra, M., Xu, X., and H. Bidgoli, "An
              Optional Encoding of the BIFT-id Field in the non-MPLS
              BIER Encapsulation", Work in Progress, Internet-Draft,
              draft-ietf-bier-non-mpls-bift-encoding-04, 30 May 2021,
              <https://www.ietf.org/archive/id/draft-ietf-bier-non-mpls-
              bift-encoding-04.txt>.

   [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-05, 19 November 2021,
              <https://www.ietf.org/archive/id/draft-ietf-bier-ospfv3-
              extensions-05.txt>.

   [I-D.zzhang-bier-rift]
              Zhang, Z., Ma, S., and Z. Zhang, "Supporting BIER with
              RIFT", Work in Progress, Internet-Draft, draft-zzhang-
              bier-rift-00, 5 March 2018,
              <https://www.ietf.org/archive/id/draft-zzhang-bier-rift-
              00.txt>.

   [RFC1195]  Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
              dual environments", RFC 1195, DOI 10.17487/RFC1195,
              December 1990, <https://www.rfc-editor.org/info/rfc1195>.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328,
              DOI 10.17487/RFC2328, April 1998,
              <https://www.rfc-editor.org/info/rfc2328>.



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   [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>.

   [RFC5304]  Li, T. and R. Atkinson, "IS-IS Cryptographic
              Authentication", RFC 5304, DOI 10.17487/RFC5304, October
              2008, <https://www.rfc-editor.org/info/rfc5304>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <https://www.rfc-editor.org/info/rfc5305>.

   [RFC5308]  Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
              DOI 10.17487/RFC5308, October 2008,
              <https://www.rfc-editor.org/info/rfc5308>.

   [RFC5310]  Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
              and M. Fanto, "IS-IS Generic Cryptographic
              Authentication", RFC 5310, DOI 10.17487/RFC5310, February
              2009, <https://www.rfc-editor.org/info/rfc5310>.

   [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, November
              2015, <https://www.rfc-editor.org/info/rfc7684>.

   [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>.

   [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>.

Authors' Addresses

   Senthil Dhanaraj
   Huawei
   Email: senthil.dhanaraj.ietf@gmail.com


   Gang Yan
   Huawei
   Email: yangang@huawei.com




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   IJsbrand Wijnands
   Individual
   Email: ice@braindump.be


   Peter Psenak
   Cisco Systems, Inc.
   Email: ppsenak@cisco.com


   Zhaohui Zhang (editor)
   Juniper Networks.
   Email: zzhang@juniper.net


   Jingrong Xie
   Huawei
   Email: xiejingrong@huawei.com

































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