BIER Underlay Path Calculation Algorithm and Constraints
draft-ietf-bier-bar-ipa-07

Document Type Active Internet-Draft (bier WG)
Authors Zhaohui Zhang  , Tony Przygienda  , Andrew Dolganow  , Hooman Bidgoli  , IJsbrand Wijnands  , Arkadiy Gulko 
Last updated 2020-09-22
Stream IETF
Intended RFC status Proposed Standard
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Doc Shepherd Follow-up Underway
Document shepherd Greg Mirsky
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BIER                                                            Z. Zhang
Internet-Draft                                             A. Przygienda
Updates: 8401,8444 (if approved)                        Juniper Networks
Intended status: Standards Track                             A. Dolganow
Expires: March 26, 2021                                       Individual
                                                              H. Bidgoli
                                                                   Nokia
                                                             I. Wijnands
                                                           Cisco Systems
                                                                A. Gulko
                                                         Thomson Reuters
                                                      September 22, 2020

        BIER Underlay Path Calculation Algorithm and Constraints
                       draft-ietf-bier-bar-ipa-07

Abstract

   This document specifies general rules for interaction between the BAR
   (BIER Algorithm) and IPA (IGP Algorithm) fields defined in ISIS/
   OSPFv2 Extensions for BIER.  The semantics for the BAR and IPA fields
   (when both or any of them is non-zero) defined in this document
   updates the semantics defined in RFC 8401 and RFC 8444.

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."

Zhang, et al.            Expires March 26, 2021                 [Page 1]
Internet-Draft                bier-bar-ipa                September 2020

   This Internet-Draft will expire on March 26, 2021.

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
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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.  General Rules for the BAR and IPA fields  . . . . . . . . . .   3
     2.1.  When BAR Is Not Used  . . . . . . . . . . . . . . . . . .   4
     2.2.  Exceptions/Extensions to the General Rules  . . . . . . .   4
   3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   In Bit Index Explicit Replication (BIER) architecture [RFC8279],
   packets with a BIER encapsulation header are forwarded to the
   neighbors on the underlay paths towards the BFERs.  For each sub-
   domain, the paths are calculated in the underlay topology for the
   sub-domain, following a calculation algorithm specific to the sub-
   domain.  The <topology, algorithm> could be congruent or incongruent
   with unicast.  The topology could be a default or non-default
   topology [RFC5120].  The algorithm could be a generic IGP algorithm
   (e.g.  SPF) or could be a BIER specific one defined in the future.

   In [RFC8401] and [RFC8444], an 8-bit BAR (BIER Algorithm) field and
   8-bit IPA (IGP Algorithm) field are defined to signal the BIER
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