Tethering A BIER Router To A BIER incapable Router
draft-zzhang-bier-tether-04

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BIER                                                            Z. Zhang
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                               N. Warnke
Expires: April 2, 2020                                  Deutsche Telekom
                                                             I. Wijnands
                                                           Cisco Systems
                                                              D. Awduche
                                                                 Verizon
                                                      September 30, 2019

           Tethering A BIER Router To A BIER incapable Router
                      draft-zzhang-bier-tether-04

Abstract

   This document specifies optional procedures to optimize the handling
   of Bit Index Explicit Replication (BIER) incapable routers, by
   attaching (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", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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 2, 2020.

Zhang, et al.             Expires April 2, 2020                 [Page 1]
Internet-Draft                 bier-tether                September 2019

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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Additional Considerations . . . . . . . . . . . . . . . . . .   3
   3.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  IGP Signaling . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  BGP Signaling . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Consider the scenario in Figure 1 where router X does not support
   BIER.

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

             Figure 1: Deployment with BIER incapable routers

   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
   distance or bandwidth limited, and n is large, it becomes very
   inefficient.

Zhang, et al.             Expires April 2, 2020                 [Page 2]
Internet-Draft                 bier-tether                September 2019

   A solution to the inefficient tunneling from BFRs is to attach
   (tether) a BFRx to X as depicted in Figure 2:

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

                          Figure 2: Tethered BFRx

   Instead of BFR1 tunneling to BFR2, ..., BFRn directly, BFR1 will get
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