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Versions: 00 draft-dhanaraj-bier-lsr-ethernet-extensions

Internet Engineering Task Force                         S. Dhanaraj, Ed.
Internet-Draft                                                    Huawei
Intended status: Standards Track                            IJ. Wijnands
Expires: May 27, 2019                                          P. Psenak
                                                     Cisco Systems, Inc.
                                                                  G. Yan
                                                                  J. Xie
                                                                  Huawei
                                                       November 23, 2018


             ISIS Extensions for BIER in Non-MPLS Networks
            draft-dhanaraj-bier-isis-non-mpls-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].

   BIER in Ethernet encapsulation is an example of BIER encapsulation in
   non-MPLS networks.

   [RFC8401] specifies the required extensions to the IS-IS [RFC1195]
   protocol 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] 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




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   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 May 27, 2019.

Copyright Notice

   Copyright (c) 2018 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 . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   3.  Procedure and Packet Formats  . . . . . . . . . . . . . . . .   4
     3.1.  BIER Ethernet Encapsulation Sub-sub TLV . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  IS-IS sub-sub-TLVs for BIER Info sub-TLV Registry . . . .   7
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

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

   As stated in [RFC8296], the encapsulation of Initial Four Octets in
   BIER header for MPLS and non-MPLS networks are different.  In
   particular, the first 20-bits of the BIER header (referred as BIFT-



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   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.

   BIER in Ethernet encapsulation is an example of BIER encapsulation in
   non-MPLS networks.

      BIER in Ethernet encapsulation(BIER-ETH):
      Ethernet header is immediately followed by the BIER header.  In
      this type of encapsulation, the EtherType field in the Ethernet
      header is set to 0xAB37 which is assigned by IEEE for non-MPLS
      BIER packets as stated in [RFC8279].

   Processing and forwarding of multicast packets using the BIER-ETH
   encapsulation requires special software and hardware capabilities.
   The BFRs supporting this 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.

   [RFC8401] specifies the required extensions to the IS-IS [RFC1195]
   protocol 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 extensions to the IS-IS
   [RFC1195] protocol for supporting BIER in non-MPLS networks using
   BIER in Ethernet encapsulation.

   Support for other encapsulation types are outside the scope of this
   document.  In case of multiple encapsulation types supported by a BFR
   in a BIER sub-domain, the selection of a encapsulation type to be
   used for a BIER sub-domain is 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.




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      (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

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.  Procedure and Packet Formats

   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-TLVs under BIER Info sub-TLV to
   advertise the encapsulation capability and other associated
   parameters of the encapsulation.

   A BIER sub-domain MAY support multiple BIER encapsulation types like
   BIER-MPLS, BIER-ETH.  Within a BIER sub-domain, it is very well
   possible and allowable to share the same BFR-id for a BFR across
   different encapsulation types.  If the operator wishes to use
   different BFR-id for different encapsulation types, then he MUST
   provision different BIER sub-domain for each encapsulation type.






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   The selection of encapsulation type to be used by a BFIR or BFR for a
   sub-domain could be a matter of local policy and is outside the scope
   of this document.

   As described in Section 2.2.1.1 of [RFC8296], In non-MPLS networks, a
   BIFT-id MUST be assigned for every combination of <SD, SI, BSL> that
   is to be used in that network.  Two possible means by which the BIFT-
   ids are assigned for a <SD, SI, BSL> are described in
   [I-D.ietf-bier-non-mpls-bift-encoding].

   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, would have
   to 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.

   In such case, a BFR MUST assign a contiguous range of BIFT-ids as,

      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.

3.1.  BIER Ethernet Encapsulation Sub-sub TLV

   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].





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   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.

   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:  1 octet.  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):  4 bits.  Encoded bitstring length
  as per [RFC8296].

   BIFT-id:  20 bits.  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.

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].



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   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.

5.  IANA Considerations

   The document requests new allocations from the IS-IS registries as
   follows

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

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

6.  Acknowledgments

   The author wants to thank Jeffrey (Zhaohui) Zhang and Antonie
   Przygienda for their comments and suggestions.

7.  References

7.1.  Normative 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.

   [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>.

   [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>.

   [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>.





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   [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>.

   [RFC7794]  Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and
              U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4
              and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,
              March 2016, <https://www.rfc-editor.org/info/rfc7794>.

   [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>.

7.2.  Informative References

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.






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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


   Gang Yan
   Huawei

   Email: yangang@huawei.com


   Jingrong Xie
   Huawei

   Email: xiejingrong@huawei.com





















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