A Transport-Independent Bit Index Explicit Replication (BIER) Encapsulation Header
draft-xu-bier-encapsulation-05

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Document Type Active Internet-Draft (individual)
Authors Xiaohu Xu  , somasundaram.s@alcatel-lucent.com  , Christian Jacquenet  , Robert Raszuk 
Last updated 2016-06-30
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Network Working Group                                         X. Xu, Ed.
Internet-Draft                                                    Huawei
Intended status: Standards Track                         S. Somasundaram
Expires: January 1, 2017                                  Alcatel-Lucent
                                                       C. Jacquenet, Ed.
                                                          France Telecom
                                                               R. Raszuk
                                                            Bloomberg LP
                                                           June 30, 2016

     A Transport-Independent Bit Index Explicit Replication (BIER)
                          Encapsulation Header
                     draft-xu-bier-encapsulation-05

Abstract

   Bit Index Explicit Replication (BIER) is a new multicast forwarding
   paradigm which doesn't require an explicit tree-building protocol nor
   intermediate routers to maintain any multicast state.  This document
   proposes a transport-independent BIER encapsulation header which is
   applicable regardless of the underlying transport technology.

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 January 1, 2017.

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   Copyright (c) 2016 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  BIER Header . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  BIER Header Transport . . . . . . . . . . . . . . . . . . . .   4
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Bit Index Explicit Replication (BIER) [I-D.ietf-bier-architecture] is
   a new multicast forwarding paradigm which doesn't require an explicit
   tree-building protocol nor intermediate routers to maintain any
   multicast state.  As described in [I-D.ietf-bier-architecture], BIER
   adds a header to a multicast data packet (e.g., an IP packet or an
   MPLS packet).  The BIER header carries the information needed for
   supporting the BIER forwarding procedures.  This information at least
   includes Subdomain-ID, Set-Identifier (SI) and BitString.  Subdomain-
   ID, SI and BitString are used together to identify the set of Bit-
   Forwarding Egress Routers (BFERs) to which the packet must be
   delivered.  In addition, a Protocol Type field is neccessary to
   indicate what type of payload is following the BIER header.  This
   document proposes a transport-independent BIER encapsulation header
   which is applicable regardless of the underlying transport
   technology.

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 RFC 2119 [RFC2119].

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2.  Terminology

   This memo makes use of the terms defined in
   [I-D.ietf-bier-architecture].

3.  BIER Header

   The BIER header is shown in Figure 1.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Ver  |   BSL |        Reserved           |         SI        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           BFIR-ID             |  Sub-domain   |   Protocol    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Entropy             |      DS       |      TTL      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                BitString  (first 32 bits)                     ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ~                                                               ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ~                BitString  (last 32 bits)                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     Figure 1: BIER Header Format.

      Ver(sion): a 4-bit field identifying the version of the BIER
      header.  This document specifies version 0 of the BIER header.

      BSL: Bit String Length.  If k is the length of the BitString, the
      value of this field is log2(k)-5.  However, only the following
      values are supported [I-D.ietf-bier-mpls-encapsulation] :

      *  64 bits

      *  128 bits

      *  256 bits

      *  512 bits

      *  1024 bits

      *  2048 bits

      *  4096 bits

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      The value of the BSL field MUST NOT be set to any value other than
      those listed above.  A received packet containing another value in
      this field SHOULD be discarded, and an error logged.

      SI: a 10-bit field encoding the Set-Identifier (SI) for this
      packet.

      BFIR-ID: a 2-octet field encoding the BFR-ID of the Bit-Forwarding
      Ingress Router (BFIR), in the BIER sub-domain where the packet is
      forwarded to.

      Sub-domain: a one-octet field encoding the sub-domain where the
      packet is forwarded to.

      Protocol: a one-octet field indicating the protocol type of the
      BIER payload as per the protocol numbers used in the Protocol
      field [RFC5237]of the IPv4 header and the Next Header field of an
      IPv6 header.  The valid BIER payload types include (but are not
      limited to) IPv4, IPv6, MPLS, VXLAN [RFC7348],VXLAN-GPE
      [I-D.ietf-nvo3-vxlan-gpe].  The corresponding IP Protocol numbers
      for VXLAN and VXLAN-GPE are to be allocated by IANA.

      Entropy: a 2-octet field containing an "entropy" value that can be
      used for load balancing purposes.

      BitString: a variable-length BitString field that, together with
      the SI field, identifies all the destination BFERs for this
      packet.

      DS: The usage of this field is no different from that of the
      Differentiated Services (DS) field of IPv4 and IPv6 headers.
      [RFC2474].

      TTL: The usage of this field is no different from that of the Time
      To Live (TTL) field in the IPv4 header.

4.  BIER Header Transport

   Since the BIER header format as specified in Section 3 is transport-
   independent by design, it can be carried with any type of transport
   encapsulation headers, such as an Ethernet header, a PPP header, an
   IP header, an MPLS header, a GRE header, an UDP header etc.  Any
   possible transport encapsulation header must be able to indicate the
   payload is an BIER header.  For instance, in the BIER-in-MAC
   encapsulation case, the EtherType [ETYPES] field of the Ethernet
   header is used for that purpose.  In the BIER-in-IP encapsulation

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   case, the Protocol field of the IPv4 header or or the Next-Header
   field of the IPv6 header are used.  In the BIER-in-MPLS encapsulation
   case, either the Protocol Type field
   [I-D.xu-mpls-payload-protocol-identifier] within the MPLS packet or a
   yet-to-be-assigned Extended Special Purpose label [RFC7274] can be
   used.

5.  Acknowledgements

   Thanks Antoni Przygienda and IJsbrand Wijnands for their valuable
   comments and suggestions on this document.

6.  IANA Considerations

   This document includes a request to IANA to allocate an EtherType
   code,a PPP protocol code, an IPv4 protocol code, an IPv6 Next-Header
   code, a UDP destination port to indicate that BIER-encapsulated data
   follows.  Furthermore, this document includes a request to IANA to
   allocate IP Protocol numbers for VXLAN and VXLAN-GPE respectively.

7.  Security Considerations

   As mentioned in [I-D.ietf-bier-architecture], when BIER is paired
   with any transport underlay, it inherits the security considerations
   of the corresponding transport layer.  Also, SI and BFIR-ID fields of
   the BIER header may carry values other than those intended by the
   BFIR at the risk of misdelivering the packet.  Means to protect BFR
   routers against Man-in-the-Middle and Denial of Service attacks must
   be provided.

8.  References

8.1.  Normative References

   [ETYPES]   The IEEE Registration Authority, "IEEE 802 Numbers", 2012.

   [I-D.ietf-bier-architecture]
              Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
              S. Aldrin, "Multicast using Bit Index Explicit
              Replication", draft-ietf-bier-architecture-03 (work in
              progress), January 2016.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

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8.2.  Informative References

   [I-D.ietf-bier-mpls-encapsulation]
              Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., and
              S. Aldrin, "Encapsulation for Bit Index Explicit
              Replication in MPLS Networks", draft-ietf-bier-mpls-
              encapsulation-04 (work in progress), April 2016.

   [I-D.ietf-nvo3-vxlan-gpe]
              Kreeger, L. and U. Elzur, "Generic Protocol Extension for
              VXLAN", draft-ietf-nvo3-vxlan-gpe-02 (work in progress),
              April 2016.

   [I-D.xu-mpls-payload-protocol-identifier]
              Xu, X., "MPLS Payload Protocol Identifier", draft-xu-mpls-
              payload-protocol-identifier-01 (work in progress), June
              2016.

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              DOI 10.17487/RFC2474, December 1998,
              <http://www.rfc-editor.org/info/rfc2474>.

   [RFC5237]  Arkko, J. and S. Bradner, "IANA Allocation Guidelines for
              the Protocol Field", BCP 37, RFC 5237,
              DOI 10.17487/RFC5237, February 2008,
              <http://www.rfc-editor.org/info/rfc5237>.

   [RFC7274]  Kompella, K., Andersson, L., and A. Farrel, "Allocating
              and Retiring Special-Purpose MPLS Labels", RFC 7274,
              DOI 10.17487/RFC7274, June 2014,
              <http://www.rfc-editor.org/info/rfc7274>.

   [RFC7348]  Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
              L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
              eXtensible Local Area Network (VXLAN): A Framework for
              Overlaying Virtualized Layer 2 Networks over Layer 3
              Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
              <http://www.rfc-editor.org/info/rfc7348>.

Authors' Addresses

   Xiaohu Xu (editor)
   Huawei

   Email: xuxiaohu@huawei.com

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   S Somasundaram
   Alcatel-Lucent

   Email: somasundaram.s@alcatel-lucent.com

   Christian Jacquenet (editor)
   France Telecom

   Email: christian.jacquenet@orange.com

   Robert Raszuk
   Bloomberg LP

   Email: robert@raszuk.net

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