Framework for Generalized Multi-Protocol Label Switching (GMPLS)-based Control of Synchronous Digital Hierarchy/Synchronous Optical Networking (SDH/SONET) Networks
RFC 4257

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Network Working Group                                       G. Bernstein
Request for Comments: 4257                             Grotto Networking
Category: Informational                                        E. Mannie
                                                                Perceval
                                                               V. Sharma
                                                          Metanoia, Inc.
                                                                 E. Gray
                                                Marconi Corporation, plc
                                                           December 2005

             Framework for Generalized Multi-Protocol Label
         Switching (GMPLS)-based Control of Synchronous Digital
     Hierarchy/Synchronous Optical Networking (SDH/SONET) Networks

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 (2005).

Abstract

   Generalized Multi-Protocol Label Switching (GMPLS) is a suite of
   protocol extensions to MPLS to make it generally applicable, to
   include, for example, control of non packet-based switching, and
   particularly, optical switching.  One consideration is to use GMPLS
   protocols to upgrade the control plane of optical transport networks.
   This document illustrates this process by describing those extensions
   to GMPLS protocols that are aimed at controlling Synchronous Digital
   Hierarchy (SDH) or Synchronous Optical Networking (SONET) networks.
   SDH/SONET networks make good examples of this process for a variety
   of reasons.  This document highlights extensions to GMPLS-related
   routing protocols to disseminate information needed in transport path
   computation and network operations, together with (G)MPLS protocol
   extensions required for the provisioning of transport circuits.  New
   capabilities that an GMPLS control plane would bring to SDH/SONET
   networks, such as new restoration methods and multi-layer circuit
   establishment, are also discussed.

Bernstein, et al.            Informational                      [Page 1]
RFC 4257            GMPLS based Control of SDH/SONET       December 2005

Table of Contents

   1. Introduction ....................................................3
      1.1. MPLS Overview ..............................................3
      1.2. SDH/SONET Overview .........................................5
      1.3. The Current State of Circuit Establishment in
           SDH/SONET Networks .........................................7
           1.3.1. Administrative Tasks ................................8
           1.3.2. Manual Operations ...................................8
           1.3.3. Planning Tool Operation .............................8
           1.3.4. Circuit Provisioning ................................8
      1.4. Centralized Approach versus Distributed Approach ...........9
           1.4.1. Topology Discovery and Resource Dissemination ......10
           1.4.2. Path Computation (Route Determination) .............10
           1.4.3. Connection Establishment (Provisioning) ............10
      1.5. Why SDH/SONET Will Not Disappear Tomorrow .................12
   2. GMPLS Applied to SDH/SONET .....................................13
      2.1. Controlling the SDH/SONET Multiplex .......................13
      2.2. SDH/SONET LSR and LSP Terminology .........................14
   3. Decomposition of the GMPLS Circuit-Switching Problem Space .....14
   4. GMPLS Routing for SDH/SONET ....................................15
      4.1. Switching Capabilities ....................................16
           4.1.1. Switching Granularity ..............................16
           4.1.2. Signal Concatenation Capabilities ..................17
           4.1.3. SDH/SONET Transparency .............................19
      4.2. Protection ................................................20
      4.3. Available Capacity Advertisement ..........................23
      4.4. Path Computation ..........................................24
   5. LSP Provisioning/Signaling for SDH/SONET .......................25
      5.1. What Do We Label in SDH/SONET?  Frames or Circuits? .......25
      5.2. Label Structure in SDH/SONET ..............................26
      5.3. Signaling Elements ........................................27
   6. Summary and Conclusions ........................................29
   7. Security Considerations ........................................29
   8. Acknowledgements ...............................................30
   9. Informative References .........................................31
   10. Acronyms ......................................................33

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