Tethering A BIER Router To A BIER-incapable Router
draft-zzhang-bier-tether-02

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Last updated 2019-07-06 (latest revision 2019-01-30)
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BIER                                                            Z. Zhang
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                               N. Warnke
Expires: January 7, 2020                                Deutsche Telekom
                                                             I. Wijnands
                                                           Cisco Systems
                                                              D. Awduche
                                                                 Verizon
                                                            July 6, 2019

           Tethering A BIER Router To A BIER-incapable Router
                      draft-zzhang-bier-tether-02

Abstract

   This document specifies optional procedures to optimize the handling
   of Bit Index Explicit Replication (BIER) 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 January 7, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Zhang, et al.            Expires January 7, 2020                [Page 1]
Internet-Draft                 bier-tether                     July 2019

   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
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Table of Contents

   1.  Terminologies . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Additional Considerations . . . . . . . . . . . . . . . . . .   4
   4.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Advertising from Helped Node  . . . . . . . . . . . . . .   6
     4.2.  Advertising from Helper Node  . . . . . . . . . . . . . .   7
     4.3.  Procedures for BGP Signaling  . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

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 to those BFRs.  If X's connections to BFRs are long

Zhang, et al.            Expires January 7, 2020                [Page 2]
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   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:

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