Generalized Multi-Protocol Label Switching (GMPLS) Recovery Functional Specification
RFC 4426

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Network Working Group                                       J. Lang, Ed.
Request for Comments: 4426                           B. Rajagopalan, Ed.
Category: Standards Track                          D. Papadimitriou, Ed.
                                                              March 2006

           Generalized Multi-Protocol Label Switching (GMPLS)
                   Recovery Functional Specification

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document presents a functional description of the protocol
   extensions needed to support Generalized Multi-Protocol Label
   Switching (GMPLS)-based recovery (i.e., protection and restoration).
   Protocol specific formats and mechanisms will be described in
   companion documents.

Table of Contents

   1.  Introduction .................................................  2
       1.1.  Conventions Used in This Document ......................  3
   2.  Span Protection ..............................................  3
       2.1.  Unidirectional 1+1 Dedicated Protection ................  4
       2.2.  Bi-directional 1+1 Dedicated Protection ................  5
       2.3.  Dedicated 1:1 Protection with Extra Traffic ............  6
       2.4.  Shared M:N Protection ..................................  8
       2.5.  Messages ............................................... 10
             2.5.1.  Failure Indication Message ..................... 10
             2.5.2.  Switchover Request Message ..................... 11
             2.5.3.  Switchover Response Message .................... 11
       2.6.  Preventing Unintended Connections ...................... 12
   3.  End-to-End (Path) Protection and Restoration ................. 12
       3.1.  Unidirectional 1+1 Protection .......................... 12
       3.2.  Bi-directional 1+1 Protection .......................... 12
             3.2.1.  Identifiers .................................... 13
             3.2.2.  Nodal Information .............................. 14

Lang, et al.                Standards Track                     [Page 1]
RFC 4426        GMPLS Recovery Functional Specification       March 2006

             3.2.3.  End-to-End Failure Indication Message .......... 14
             3.2.4.  End-to-End Failure Acknowledgement Message ..... 15
             3.2.5.  End-to-End Switchover Request Message .......... 15
             3.2.6.  End-to-End Switchover Response Message ......... 15
       3.3.  Shared Mesh Restoration ................................ 15
             3.3.1.  End-to-End Failure Indication and
                     Acknowledgement Message ........................ 16
             3.3.2.  End-to-End Switchover Request Message .......... 16
             3.3.3.  End-to-End Switchover Response Message ......... 17
   4.  Reversion and Other Administrative Procedures ................ 17
   5.  Discussion ................................................... 18
       5.1.  LSP Priorities During Protection ....................... 18
   6.  Security Considerations ...................................... 19
   7.  Contributors ................................................. 20
   8.  References ................................................... 21
       8.1.  Normative References ................................... 21
       8.2.  Informative References ................................. 22

1.  Introduction

   A requirement for the development of a common control plane for both
   optical and electronic switching equipment is that there must be
   signaling, routing, and link management mechanisms that support data
   plane fault recovery.  In this document, the term "recovery" is
   generically used to denote both protection and restoration; the
   specific terms "protection" and "restoration" are used only when
   differentiation is required.  The subtle distinction between
   protection and restoration is made based on the resource allocation
   done during the recovery period (see [RFC4427]).

   A label-switched path (LSP) may be subject to local (span), segment,
   and/or end-to-end recovery.  Local span protection refers to the
   protection of the link (and hence all the LSPs marked as required for
   span protection and routed over the link) between two neighboring
   switches.  Segment protection refers to the recovery of an LSP
   segment (i.e., an SNC in the ITU-T terminology) between two nodes,
   i.e., the boundary nodes of the segment.  End-to-end protection
   refers to the protection of an entire LSP from the ingress to the
   egress port.  The end-to-end recovery models discussed in this