Path Segment in MPLS Based Segment Routing Network
draft-ietf-spring-mpls-path-segment-00

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Last updated 2019-03-11
Replaces draft-cheng-spring-mpls-path-segment
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Network Working Group                                           W. Cheng
Internet-Draft                                                     H. Li
Intended status: Standards Track                            China Mobile
Expires: September 9, 2019                                       M. Chen
                                                                  Huawei
                                                               R. Gandhi
                                                     Cisco Systems, Inc.
                                                               R. Zigler
                                                                Broadcom
                                                          March 08, 2019

           Path Segment in MPLS Based Segment Routing Network
                 draft-ietf-spring-mpls-path-segment-00

Abstract

   A Segment Routing (SR) path is identified by an SR segment list, one
   or partial segments of the list cannot uniquely identify the SR path.
   Path identification is a pre-requisite for various use-cases such as
   performance measurement (PM) of an SR path.

   This document defines a new type of segment that is referred to as
   Path Segment, which is used to identify an SR path.  When used, it is
   inserted at the ingress node of the SR path and immediately follows
   the last segment of the SR path.  The Path Segment will not be popped
   off until it reaches the egress node of the SR path.

   Path Segment can be used by the egress node to implement path
   identification hence to support various use-cases including SR path
   PM, end-to-end 1+1 SR path protection and bidirectional SR paths
   correlation.

Status of This Memo

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Cheng, et al.           Expires September 9, 2019               [Page 1]
Internet-Draft           Path Segment in SR-MPLS              March 2019

   This Internet-Draft will expire on September 9, 2019.

Copyright Notice

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Path Segment  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Nesting of Path Segments  . . . . . . . . . . . . . . . . . .   5
   4.  Path Segment Allocation . . . . . . . . . . . . . . . . . . .   6
   5.  Path Segment for PM . . . . . . . . . . . . . . . . . . . . .   6
   6.  Path Segment for Bi-directional SR Path . . . . . . . . . . .   7
   7.  Path Segment for End-to-end Path Protection . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     12.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     12.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Segment Routing (SR) [RFC8402] is a source routed forwarding method
   that allows to directly encode forwarding instructions (called
   segments) in each packet, hence it enables to steer traffic through a
   network without the per-flow states maintained on the transit nodes.
   Segment Routing can be instantiated on MPLS data plane or IPv6 data
   plane.  The former is called SR-MPLS, the latter is called SRv6
   [RFC8402].  SR-MPLS leverages the MPLS label stack to construct SR
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