Segment Routing Policies for Path Segment and Bidirectional Path
draft-li-idr-sr-policy-path-segment-distribution-01

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Interdomain Routing Working Group                                  C. Li
Internet-Draft                                                   M. Chen
Intended status: Standards Track                                 J. Dong
Expires: April 25, 2019                                            Z. Li
                                                     Huawei Technologies
                                                        October 22, 2018

    Segment Routing Policies for Path Segment and Bidirectional Path
          draft-li-idr-sr-policy-path-segment-distribution-01

Abstract

   An SR policy is a set of candidate SR paths consisting of one or more
   segment lists with necessary path attributes.  For each SR path, it
   may also have its own path attributes, and Path Segment is one of
   them.  A Path Segment is defined to identify an SR path, which can be
   used for performance measurement, path correlation, and end-2-end
   path protection.  Path Segment can be also used to correlate two
   unidirctional SR paths into a bidirectional SR path which is required
   in some scenarios, for example, mobile backhaul transport network.

   This document defines extensions to BGP to distribute SR policies
   carrying Path Segment and bidirectional path information.

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 RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on April 25, 2019.

Li, et al.               Expires April 25, 2019                 [Page 1]
Internet-Draft   Path ID and Bi-directional Path in BGP     October 2018

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SR Policy for Path Identifier . . . . . . . . . . . . . . . .   3
     3.1.  SR Path Segment Sub-TLV . . . . . . . . . . . . . . . . .   4
   4.  SR Policy for Bidirectional Path  . . . . . . . . . . . . . .   5
     4.1.  SR Bidirectional Path Sub-TLV . . . . . . . . . . . . . .   6
     4.2.  SR Reverse Path Segment List Sub-TLV  . . . . . . . . . .   7
   5.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Segment routing (SR) [RFC8402] is a source routing paradigm that
   explicitly indicates the forwarding path for packets at the ingress
   node.  The ingress node steers packets into a specific path according
   to the Segment Routing Policy ( SR Policy) as defined in
   [I-D.ietf-spring-segment-routing-policy].  For distributing SR
   policies to the headend, [I-D.ietf-idr-segment-routing-te-policy]
   specifies a mechanism by using BGP, and new sub-TLVs are defined for
   SR Policies in BGP UPDATE message.

   In many use cases such as performance measurement, the path to which
   the packets belong is required to be identified.  Futhermore, in some
   scenarios, for example, mobile backhaul transport network, there are
   requirements to support bidirectional path.  However, there is no
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