Explicit Path Routing for Dynamic Multi-Segment Pseudowires
RFC 7392

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Internet Engineering Task Force (IETF)                          P. Dutta
Request for Comments: 7392                                      M. Bocci
Category: Standards Track                                 Alcatel-Lucent
ISSN: 2070-1721                                               L. Martini
                                                           Cisco Systems
                                                           December 2014

      Explicit Path Routing for Dynamic Multi-Segment Pseudowires

Abstract

   When set up through an explicit path, dynamic Multi-Segment
   Pseudowires (MS-PWs) may be required to provide a simple solution for
   1:1 protection with diverse primary and backup MS-PWs for a service,
   or to enable controlled signaling (strict or loose) for special MS-
   PWs.  This document specifies the extensions and procedures required
   to enable dynamic MS-PWs to be established along explicit paths.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7392.

Copyright Notice

   Copyright (c) 2014 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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   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.

Dutta, et al.                Standards Track                    [Page 1]
RFC 7392                 MS-PW Explicit Routing            December 2014

Table of Contents

   1. Introduction ....................................................2
   2. Requirements Language and Terminology ...........................3
   3. Explicit Path in MS-PW Signaling ................................3
      3.1. S-PE Addressing ............................................3
      3.2. Explicit Route TLV (ER-TLV) ................................3
      3.3. Explicit Route Hop TLV (ER-Hop TLV) ........................4
      3.4. ER-Hop Semantics ...........................................4
           3.4.1. ER-Hop Type: IPv4 Prefix ............................4
           3.4.2. ER-Hop Type: IPv6 Prefix ............................4
           3.4.3. ER-Hop Type: L2 PW Address ..........................5
   4. Explicit Route TLV Processing ...................................6
      4.1. Next-Hop Selection .........................................6
      4.2. Adding ER Hops to the Explicit Route TLV ...................8
   5. IANA Considerations .............................................8
   6. Security Considerations .........................................8
   7. Normative References ............................................9
   Acknowledgements ...................................................9
   Authors' Addresses ................................................10

1.  Introduction

   Procedures for dynamically establishing Multi-Segment Pseudowires
   (MS-PWs), where their paths are automatically determined using a
   dynamic routing protocol, are defined in [RFC7267].  For 1:1
   protection of MS-PWs with primary and backup paths, MS-PWs need to be
   established through a diverse set of Switching Provider Edges (S-PEs)
   to avoid any single points of failure at the PW level.  [RFC7267]
   allows this through BGP-based mechanisms.  This document defines an
   additional mechanism that allows Source Terminating Provider Edges
   (ST-PEs) to explicitly choose the path that a PW would take through
   the intervening S-PEs.  Explicit path routing of dynamic MS-PWs may
   also be required for controlled setup of dynamic MS-PWs and network
   resource management.

   Note that in many deployments the ST-PE will not have a view of the
   topology of S-PEs and so the explicit route will need to be supplied
   from a management application.  How that management application
   determines the explicit route is outside the scope of this document.

Dutta, et al.                Standards Track                    [Page 2]
RFC 7392                 MS-PW Explicit Routing            December 2014

2.  Requirements Language and Terminology