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

Document Type Active Internet-Draft (bier WG)
Authors Zhaohui Zhang  , Nils Warnke  , IJsbrand Wijnands  , Daniel Awduche 
Last updated 2020-09-23 (latest revision 2020-08-20)
Replaces draft-zzhang-bier-tether
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BIER                                                            Z. Zhang
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                               N. Warnke
Expires: February 21, 2021                              Deutsche Telekom
                                                             I. Wijnands
                                                           Cisco Systems
                                                              D. Awduche
                                                                 Verizon
                                                         August 20, 2020

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

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 21, 2021.

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Copyright Notice

   Copyright (c) 2020 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
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   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.

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.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  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

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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 attach
   (tether) a BFRx to X as depicted in Figure 2:

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