A Framework for the Control of Wavelength Switched Optical Networks (WSONs) with Impairments
RFC 6566

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Internet Engineering Task Force (IETF)                       Y. Lee, Ed.
Request for Comments: 6566                                        Huawei
Category: Informational                                G. Bernstein, Ed.
ISSN: 2070-1721                                        Grotto Networking
                                                                   D. Li
                                                                  Huawei
                                                           G. Martinelli
                                                                   Cisco
                                                              March 2012

                     A Framework for the Control of
     Wavelength Switched Optical Networks (WSONs) with Impairments

Abstract

   As an optical signal progresses along its path, it may be altered by
   the various physical processes in the optical fibers and devices it
   encounters.  When such alterations result in signal degradation,
   these processes are usually referred to as "impairments".  These
   physical characteristics may be important constraints to consider
   when using a GMPLS control plane to support path setup and
   maintenance in wavelength switched optical networks.

   This document provides a framework for applying GMPLS protocols and
   the Path Computation Element (PCE) architecture to support
   Impairment-Aware Routing and Wavelength Assignment (IA-RWA) in
   wavelength switched optical networks.  Specifically, this document
   discusses key computing constraints, scenarios, and architectural
   processes: routing, wavelength assignment, and impairment validation.
   This document does not define optical data plane aspects; impairment
   parameters; or measurement of, or assessment and qualification of, a
   route; rather, it describes the architectural and information
   components for protocol solutions.

Lee, et al.                   Informational                     [Page 1]
RFC 6566            Framework for Optical Impairments         March 2012

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see 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/rfc6566.

Copyright Notice

   Copyright (c) 2012 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   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.

Lee, et al.                   Informational                     [Page 2]
RFC 6566            Framework for Optical Impairments         March 2012

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................4
   3. Applicability ...................................................6
   4. Impairment-Aware Optical Path Computation .......................7
      4.1. Optical Network Requirements and Constraints ...............8
           4.1.1. Impairment-Aware Computation Scenarios ..............9
           4.1.2. Impairment Computation and
                  Information-Sharing Constraints ....................10
           4.1.3. Impairment Estimation Process ......................11
      4.2. IA-RWA Computation and Control Plane Architectures ........13
           4.2.1. Combined Routing, WA, and IV .......................15
           4.2.2. Separate Routing, WA, or IV ........................15
           4.2.3. Distributed WA and/or IV ...........................16
      4.3. Mapping Network Requirements to Architectures .............16
   5. Protocol Implications ..........................................19
      5.1. Information Model for Impairments .........................19
      5.2. Routing ...................................................20
      5.3. Signaling .................................................21
      5.4. PCE .......................................................21