A Unified Approach to IP Segment Routing
draft-bryant-mpls-unified-ip-sr-01

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Last updated 2017-08-11 (latest revision 2017-06-28)
Replaced by draft-xu-mpls-sr-over-ip
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MPLS Working Group                                        S. Bryant, Ed.
Internet-Draft                                                    Huawei
Intended status: Standards Track                          A. Farrel, Ed.
Expires: February 12, 2018                                      J. Drake
                                                        Juniper Networks
                                                         August 11, 2017

                A Unified Approach to IP Segment Routing
                   draft-bryant-mpls-unified-ip-sr-01

Abstract

   Segment routing is a source routed forwarding method that allows
   packets to be steered through a network on paths other than the
   shortest path derived from the routing protocol.  The approach uses
   information encoded in the packet header to partially or completely
   specify the route the packet takes through the network, and does not
   make use of a signaling protocol to pre-install paths in the network.

   Two different encapsulations have been defined to enable segment
   routing in an MPLS network and in an IPv6 network.  While
   acknowledging that there is a strong need to support segment routing
   in both environments, this document defines a converged, unified
   approach to segment routing that enables a single mechanism to be
   applied in both types of network.  The resulting approach is also
   applicable to IPv4 networks without the need for any changes to the
   IPv4 specification.

   This document makes no changes to the segment routing architecture
   and builds on existing protocol mechanisms such as the encapsulation
   of MPLS within UDP defined in RFC 7510.

   No new procedures are introduced, but existing mechanisms are
   combined to achieve the desired result.

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 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

Bryant, et al.          Expires February 12, 2018               [Page 1]
Internet-Draft            Unified SR using MPLS              August 2017

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   This Internet-Draft will expire on February 12, 2018.

Copyright Notice

   Copyright (c) 2017 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  The Unified Segment Routing Protocol Stack  . . . . . . . . .   4
   3.  The Segment Routing Instruction Stack . . . . . . . . . . . .   6
     3.1.  TTL . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  UDP/IP Encapsulation. . . . . . . . . . . . . . . . . . . . .   7
   5.  Elements of Procedure . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Domain Ingress  . . . . . . . . . . . . . . . . . . . . .   8
     5.2.  Legacy Transit  . . . . . . . . . . . . . . . . . . . . .   8
     5.3.  On-Path Pass-Through SR Nodes . . . . . . . . . . . . . .   9
     5.4.  SR Transit Nodes  . . . . . . . . . . . . . . . . . . . .   9
     5.5.  Penultimate SR Transit  . . . . . . . . . . . . . . . . .  10
     5.6.  Domain Egress . . . . . . . . . . . . . . . . . . . . . .  10
   6.  Modes of Deployment . . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Interconnection of SR Domains . . . . . . . . . . . . . .  10
     6.2.  SR Within and IP Network  . . . . . . . . . . . . . . . .  11
   7.  Control Plane . . . . . . . . . . . . . . . . . . . . . . . .  12
   8.  OAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
   9.  Comparison with SRv6  . . . . . . . . . . . . . . . . . . . .  13
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