Multicast Using Bit Index Explicit Replication (BIER)
RFC 8279

Document Type RFC - Experimental (November 2017; No errata)
Last updated 2017-11-20
Replaces draft-wijnands-bier-architecture
Stream IETF
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Stream WG state Submitted to IESG for Publication
Document shepherd Greg Shepherd
Shepherd write-up Show (last changed 2017-06-14)
IESG IESG state RFC 8279 (Experimental)
Consensus Boilerplate Yes
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Send notices to Greg Shepherd <gjshep@gmail.com>
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Internet Engineering Task Force (IETF)                 IJ. Wijnands, Ed.
Request for Comments: 8279                           Cisco Systems, Inc.
Category: Experimental                                     E. Rosen, Ed.
ISSN: 2070-1721                                   Juniper Networks, Inc.
                                                             A. Dolganow
                                                                   Nokia
                                                           T. Przygienda
                                                  Juniper Networks, Inc.
                                                               S. Aldrin
                                                            Google, Inc.
                                                           November 2017

         Multicast Using Bit Index Explicit Replication (BIER)

Abstract

   This document specifies a new architecture for the forwarding of
   multicast data packets.  It provides optimal forwarding of multicast
   packets through a "multicast domain".  However, it does not require a
   protocol for explicitly building multicast distribution trees, nor
   does it require intermediate nodes to maintain any per-flow state.
   This architecture is known as "Bit Index Explicit Replication"
   (BIER).  When a multicast data packet enters the domain, the ingress
   router determines the set of egress routers to which the packet needs
   to be sent.  The ingress router then encapsulates the packet in a
   BIER header.  The BIER header contains a bit string in which each bit
   represents exactly one egress router in the domain; to forward the
   packet to a given set of egress routers, the bits corresponding to
   those routers are set in the BIER header.  The procedures for
   forwarding a packet based on its BIER header are specified in this
   document.  Elimination of the per-flow state and the explicit tree-
   building protocols results in a considerable simplification.

Wijnands, et al.              Experimental                      [Page 1]
RFC 8279                   Multicast with BIER             November 2017

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  This document is a product of the Internet Engineering
   Task Force (IETF).  It represents the consensus of the IETF
   community.  It has received public review and has been approved for
   publication by the Internet Engineering Steering Group (IESG).  Not
   all documents approved by the IESG are a candidate for any level of
   Internet Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8279.

Copyright Notice

   Copyright (c) 2017 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.

Wijnands, et al.              Experimental                      [Page 2]
RFC 8279                   Multicast with BIER             November 2017

Table of Contents

   1. Introduction ....................................................4
   2. The BFR Identifier and BFR-Prefix ...............................7
   3. Encoding BFR Identifiers in BitStrings ..........................8
   4. Layering .......................................................11
      4.1. The Routing Underlay ......................................11
      4.2. The BIER Layer ............................................12
      4.3. The Multicast Flow Overlay ................................13
   5. Advertising BFR-ids and BFR-Prefixes ...........................13
   6. BIER Intra-Domain Forwarding Procedures ........................15
      6.1. Overview ..................................................15
      6.2. BFR Neighbors .............................................17
      6.3. The Bit Index Routing Table ...............................18
      6.4. The Bit Index Forwarding Table ............................19
      6.5. The BIER Forwarding Procedure .............................20
      6.6. Examples of BIER Forwarding ...............................23
           6.6.1. Example 1 ..........................................23
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