Tethering A BIER Router To A BIER-incapable Router
draft-zzhang-bier-tether-00

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BIER                                                            Z. Zhang
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                               N. Warnke
Expires: April 24, 2019                                 Deutsche Telekom
                                                             I. Wijnands
                                                           Cisco Systems
                                                        October 21, 2018

           Tethering A BIER Router To A BIER-incapable Router
                      draft-zzhang-bier-tether-00

Abstract

   This document specifies optional procedures to optimize the handling
   of Bit Index Explicit Replication (BIER) [RFC8279] incapable routers,
   by tethering a BIER router to a BIER incapable router.

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
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   This Internet-Draft will expire on April 24, 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

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Internet-Draft                 bier-tether                  October 2018

   (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
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   described in the Simplified BSD License.

Table of Contents

   1.  Terminologies . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Advertising from Helped Node  . . . . . . . . . . . . . .   4
     3.2.  Advertising from Helper Node  . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Terminologies

   Familiarity with BIER architecture, protocols and procedures is
   assumed.  Some terminologies are listed below for convenience.

   [To be added].

2.  Introduction

   Consider the following scenario where router X does not support BIER.

                              ------ BFR2 ------- BFER2
                             /
      BFER1 ---  BFR1 ---- X ------- BFR3 ------- BFER3
                             .........
                             \
                              ------ BFRn ------- BFERn

   For BFR1 to forward BIER traffic towards BFR2...BFRn, it needs to
   tunnel individual copies through X.  This degrades to "ingress"
   replication on those BFRs.  If X's connections to BFRs are long
   distance or bandwidth limited, and n is large, it becomes very
   inefficient.

   A solution to the inefficient tunneling from BFRs is to tether a BFRx
   to X:

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                              ------ BFR2 ------- BFER2
                             /
      BFER1 ---  BFR1 ---- X ------- BFR3 ------- BFER3
                          / \  .........
                         /   \
                      BFRx    ------ BFRn ------- BFERn

   Instead of BFR1 tunneling to BFR2, ..., BFRn directly, BFR1 will get
   BIER packets to BFRx, who will then tunnel to BFR2, ..., BFRn.  There
   could be fat and local pipes between the tethered BFRx and X, so
   ingress replication from BFRx is acceptable.

   For BFR1 to tunnel BIER packets to BFRx, the BFR1-BFRx tunnel need to
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