BIER Penultimate Hop Popping
draft-ietf-bier-php-03

Document Type Active Internet-Draft (bier WG)
Last updated 2019-10-03
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BIER                                                            Z. Zhang
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                         October 3, 2019
Expires: April 5, 2020

                      BIER Penultimate Hop Popping
                         draft-ietf-bier-php-03

Abstract

   Bit Index Explicit Replication (BIER) can be used as provider tunnel
   for Multicast Virtual Private Network (MVPN) [RFC6514], Global
   Table Multicast [RFC7716] or Ethernet Virtual Private Network (EVPN)
   [RFC7432].  It is possible that not all routers in the provider
   network support BIER and there are various methods to handle BIER
   incapable transit routers.  However those methods assume the MVPN/
   EVPN Provider Edges (PEs) are BIER capable.  This document specifies
   a method to allow BIER incapable routers to act as MVPN/EVPN PEs with
   BIER as the transport, by having the upstream BIER Forwarding Router
   (BFR) that is connected directly or indirectly via a tunnel to a BIER
   incapable PE remove the BIER header and send the payload to the PE.

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 RFC2119.

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 5, 2020.

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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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Specifications  . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   The BIER architecture includes three layers: the "routing underlay",
   the "BIER layer", and the "multicast flow overlay".  The multicast
   flow overlay is responsible for the BIER Forwarding Egress Routers
   (BFERs) to signal to BIER Forwarding Ingress Routers (BFIRs) that
   they are interested in receiving certain multicast flows so that
   BFIRs can encode the correct bitstring for BIER forwarding by the
   BIER layer.

   MVPN and EVPN are two similar overlays where BGP Auto-Discovery
   routes for MVPN/EVPN are exchanged among all PEs to signal which PEs
   need to receive multicast traffic for all or certain flows.
   Typically the same provider tunnel type is used for traffic to reach
   all receiving PEs.

   Consider an MVPN/EVPN deployment where enough provider routers are
   BIER capable for BIER to become the preferred the choice of provider
   tunnel.  However, some PEs cannot be upgraded to support BIER
   forwarding.  While there are ways to allow an ingress PE to send
   traffic to some PEs with one type of tunnel and send traffic to some

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   other PEs with a different type of tunnel, the procedure becomes
   complicated and forwarding is not optimized.

   One way to solve this problem is to use Penultimate Hop Popping (PHP)
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