SR Policy Extensions for Path Segment and Bidirectional Path
draft-ietf-idr-sr-policy-path-segment-00

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Last updated 2019-10-28
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Interdomain Routing Working Group                                  C. Li
Internet-Draft                                                     Z. Li
Intended status: Standards Track                     Huawei Technologies
Expires: May 1, 2020                                             H. Chen
                                                           China Telecom
                                                                W. Cheng
                                                            China Mobile
                                                          K.  Talaulikar
                                                           Cisco Systems
                                                        October 29, 2019

      SR Policy Extensions for Path Segment and Bidirectional Path
                draft-ietf-idr-sr-policy-path-segment-00

Abstract

   A Segment Routing (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
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   and may be updated, replaced, or obsoleted by other documents at any

Li, et al.                 Expires May 1, 2020                  [Page 1]
Internet-Draft   Path ID and Bi-directional Path in BGP     October 2019

   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 May 1, 2020.

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
   (https://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Path Segment in SR Policy . . . . . . . . . . . . . . . . . .   3
     3.1.  SR Path Segment Sub-TLV . . . . . . . . . . . . . . . . .   4
   4.  SR Policy for Bidirectional Path  . . . . . . . . . . . . . .   6
     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
     6.1.  Existing Registry: BGP Tunnel Encapsulation Attribute
           sub-TLVs  . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

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
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