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Analysis of Generalized Multi-Protocol Label Switching (GMPLS)-based Recovery Mechanisms (including Protection and Restoration)
RFC 4428

Network Working Group                              D. Papadimitriou, Ed.
Request for Comments: 4428                                       Alcatel
Category: Informational                                   E. Mannie, Ed.
                                                                Perceval
                                                              March 2006

 Analysis of Generalized Multi-Protocol Label Switching (GMPLS)-based
      Recovery Mechanisms (including Protection and Restoration)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document provides an analysis grid to evaluate, compare, and
   contrast the Generalized Multi-Protocol Label Switching (GMPLS)
   protocol suite capabilities with the recovery mechanisms currently
   proposed at the IETF CCAMP Working Group.  A detailed analysis of
   each of the recovery phases is provided using the terminology defined
   in RFC 4427.  This document focuses on transport plane survivability
   and recovery issues and not on control plane resilience and related
   aspects.

Table of Contents

   1. Introduction ....................................................3
   2. Contributors ....................................................4
   3. Conventions Used in this Document ...............................5
   4. Fault Management ................................................5
      4.1. Failure Detection ..........................................5
      4.2. Failure Localization and Isolation .........................8
      4.3. Failure Notification .......................................9
      4.4. Failure Correlation .......................................11
   5. Recovery Mechanisms ............................................11
      5.1. Transport vs. Control Plane Responsibilities ..............11
      5.2. Technology-Independent and Technology-Dependent
           Mechanisms ................................................12
           5.2.1. OTN Recovery .......................................12
           5.2.2. Pre-OTN Recovery ...................................13
           5.2.3. SONET/SDH Recovery .................................13

Papadimitriou & Mannie       Informational                      [Page 1]
RFC 4428               GMPLS Recovery Mechanisms              March 2006

      5.3. Specific Aspects of Control Plane-Based Recovery
           Mechanisms ................................................14
           5.3.1. In-Band vs. Out-Of-Band Signaling ..................14
           5.3.2. Uni- vs. Bi-Directional Failures ...................15
           5.3.3. Partial vs. Full Span Recovery .....................17
           5.3.4. Difference between LSP, LSP Segment and
                  Span Recovery ......................................18
      5.4. Difference between Recovery Type and Scheme ...............19
      5.5. LSP Recovery Mechanisms ...................................21
           5.5.1. Classification .....................................21
           5.5.2. LSP Restoration ....................................23
           5.5.3. Pre-Planned LSP Restoration ........................24
           5.5.4. LSP Segment Restoration ............................25
   6. Reversion ......................................................26
      6.1. Wait-To-Restore (WTR) .....................................26
      6.2. Revertive Mode Operation ..................................26
      6.3. Orphans ...................................................27
   7. Hierarchies ....................................................27
      7.1. Horizontal Hierarchy (Partitioning) .......................28
      7.2. Vertical Hierarchy (Layers) ...............................28
           7.2.1. Recovery Granularity ...............................30
      7.3. Escalation Strategies .....................................30
      7.4. Disjointness ..............................................31
           7.4.1. SRLG Disjointness ..................................32
   8. Recovery Mechanisms Analysis ...................................33
      8.1. Fast Convergence (Detection/Correlation and
           Hold-off Time) ............................................34
      8.2. Efficiency (Recovery Switching Time) ......................34
      8.3. Robustness ................................................35
      8.4. Resource Optimization .....................................36
           8.4.1. Recovery Resource Sharing ..........................37
           8.4.2. Recovery Resource Sharing and SRLG Recovery ........39
           8.4.3. Recovery Resource Sharing, SRLG

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