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Versions: (draft-dhanaraj-bier-lsr-ethernet-extensions) 00 01

Internet Engineering Task Force                         S. Dhanaraj, Ed.
Internet-Draft                                                    Huawei
Updates: 8296 (if approved)                                 IJ. Wijnands
Intended status: Standards Track                               P. Psenak
Expires: November 14, 2019                           Cisco Systems, Inc.
                                                                Z. Zhang
                                                       Juniper Networks.
                                                                  G. Yan
                                                                  J. Xie
                                                                  Huawei
                                                            May 13, 2019


                 LSR Extensions for BIER over Ethernet
               draft-ietf-bier-lsr-ethernet-extensions-00

Abstract

   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 can be supported in MPLS and non-MPLS networks.  The
   common BIER header format and encapsulation for MPLS and non-MPLS
   networks is specified in [RFC8296].

   This document specifies the required extensions to the IS-IS
   [RFC1195] and OSPFv2 [RFC2328] protocol for supporting BIER in non-
   MPLS networks using BIER in Ethernet 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 November 14, 2019.






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Copyright Notice

   Copyright (c) 2019 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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   5
   3.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  IS-IS BIER Ethernet Encapsulation Sub-sub TLV . . . . . .   5
     3.2.  OSPFv2 BIER Ethernet Encapsulation Sub-TLV  . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  IS-IS sub-sub-TLVs for BIER Info sub-TLV Registry . . . .   8
     5.2.  OSPFv2 Extended Prefix TLV Sub-TLVs Registry  . . . . . .   8
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

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 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 of the BIER header
   (referred as BIFT-id) is a "MPLS Label" in case of MPLS networks and
   is a "domain-wide-unique-value" representing the combination of SD-
   BSL-SI in case of non-MPLS networks.
   [I-D.ietf-bier-non-mpls-bift-encoding] specifies two optional ways of
   statically assigning domain-wide-unique mapping between BIFT-IDs and
   SD-BSL-SI combination.



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   However, BIER architecture [RFC8279] does NOT require domain-wide-
   unique BIFT-IDs 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 SD (SD 0),
   supports two BSLs (256 and 512), and contains 1024 BFRs.  A BFR that
   is provisioned for 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-ids:

      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.

   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 other required
   parameters specific to the encapsulation) to the other routers in
   BIER domain.  This advertisement, for example, will enable the other
   BFRs in the BIER domain in deciding, whether to include or exclude
   the advertising router from the BAR and/or IPA algorithm while
   computing the multicast path for a specific encapsulation type.




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   [RFC8401] and [RFC8444] specifies the required extensions to the IS-
   IS [RFC1195] and OSPFv2 [RFC2328] protocol respectively for the
   distribution of BIER sub-domain information including the Sub-sub-TLV
   required to support BIER in MPLS encapsulation for MPLS networks.

   This document specifies the required extensions to the IS-IS
   [RFC1195] and OSPFv2 [RFC2328] protocol for supporting BIER using
   BIER in Ethernet encapsulation with dynamically and locally assigned
   BIFT-IDs.

   Support for other encapsulation types are outside the scope of this
   document.

2.  Terminology

   Some of the terminology specified in [RFC8279] is replicated here and
   extended by necessary definitions:

   BIER:  Bit Index Explicit Replication
      (The overall architecture of forwarding multicast using a Bit
      Position).

   BIER-MPLS:  BIER in MPLS encapsulation.
      (Encapsulation of BIER header inside MPLS header in MPLS
      networks).

   BIER-ETH:  BIER in Ethernet encapsulation.
      (Encapsulation of BIER header inside Ethernet header
      (EtherType=0xAB37) in non-MPLS networks).

   BFR:  Bit Forwarding Router (A router that participates in Bit Index
      Multipoint Forwarding).  A BFR is identified by a unique BFR-
      prefix in a BIER domain.

   BIFT:  Bit Index Forwarding Table used to forward the BIER packets in
      a domain.


   BAR:  BIER Algorithm.  Used to calculate underlay nexthops
      as defined by the BAR value.

   IPA:  IGP Algorithm.  May be used to modify, enhance or replace the
      calculation of underlay paths as defined by the BAR value








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2.1.  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.

3.  Specification

   A BIER sub-domain MAY support multiple BIER encapsulation types like
   BIER-MPLS, BIER-ETH.  The different encapsulation types supported by
   a BFR in a sub-domain MUST share the same BFR-id.  This would allow
   the BFR's in transit to translate the encapsulation from one type to
   the other while forwarding the packet in the BIER sub-domain.

   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.

3.1.  IS-IS BIER Ethernet Encapsulation Sub-sub TLV

   BIER Info sub-TLV defined in [RFC8401] is used to advertise the sub-
   domain id, and other associated parameters of the sub-domain like
   BFR-id, MT, BAR, IPA.

   This document introduces new sub-sub-TLV under BIER Info sub-TLV to
   advertise the ethernet encapsulation capability and other associated
   parameters of the encapsulation.

   This sub-sub-TLV carries the information for the BIER Ethernet
   encapsulation including the BitString length supported for a certain
   <MT,SD> pair.

   It is advertised within the BIER Info sub-TLV defined in [RFC8401]
   which in-turn is carried within the TLVs 235, 237 [RFC5120] or TLVs
   135 [RFC5305], or TLV 236 [RFC5308].

   This sub-sub-TLV MAY appear multiple times within a single BIER Info
   sub-TLV.  If the same BitString length is repeated in multiple BIER
   Ethernet encapsulation sub-sub-TLVs inside the same BIER Info sub-
   TLV, the BIER Info 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      |BS Len |                  BIFT-id              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:  2 (suggested value - 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
  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)).  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].

     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 Ethernet Encapsulation Sub-sub-TLV
  containing the error MUST be ignored.

3.2.  OSPFv2 BIER Ethernet Encapsulation Sub-TLV

   BIER Sub-TLV defined in [RFC8444] is used to advertise the sub-domain
   id, and other associated parameters of the sub-domain like BFR-id,
   MT, BAR, IPA.






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   This document introduces new Sub-TLV under BIER Sub-TLV to advertise
   the ethernet encapsulation capability and other associated parameters
   of the encapsulation.

   This Sub-TLV carries the information for the BIER Ethernet
   encapsulation including the BitString length supported for a certain
   <MT,SD> pair.

   It is advertised within the BIER Sub-TLV defined in [RFC8444] which
   in-turn is carried within the OSPFv2 Extended Prefix TLV defined in
   [RFC7684].

   This Sub-TLV MAY appear multiple times within a single BIER Sub-TLV.
   If the same BitString length is repeated in multiple BIER Ethernet
   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:  11 (suggested value - 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)).  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].




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     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 Ethernet Encapsulation Sub-sub-TLV
  containing the error MUST be ignored.

   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.

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 Ethernet Encapsulation sub-sub-TLV: 2 (suggested)

5.2.  OSPFv2 Extended Prefix TLV Sub-TLVs Registry

      BIER Ethernet Encapsulation Sub-TLV: 11 (suggested)








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6.  Acknowledgments

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

7.  References

7.1.  Normative References

   [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", 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., Xu, X., and H. Bidgoli, "An Optional
              Encoding of the BIFT-id Field in the non-MPLS BIER
              Encapsulation", draft-ietf-bier-non-mpls-bift-encoding-01
              (work in progress), October 2018.







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   [I-D.zzhang-bier-rift]
              Zhang, Z., Ma, S., and Z. Zhang, "Supporting BIER with
              RIFT", draft-zzhang-bier-rift-00 (work in progress), March
              2018.

   [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>.

   [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>.







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Authors' Addresses

   Senthil Dhanaraj (editor)
   Huawei

   Email: senthil.dhanaraj.ietf@gmail.com


   IJsbrand Wijnands
   Cisco Systems, Inc.

   Email: ice@cisco.com


   Peter Psenak
   Cisco Systems, Inc.

   Email: ppsenak@cisco.com


   Zhaohui Zhang
   Juniper Networks.

   Email: zzhang@juniper.net


   Gang Yan
   Huawei

   Email: yangang@huawei.com


   Jingrong Xie
   Huawei

   Email: xiejingrong@huawei.com















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