Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy (SDH) Encoding for Link Management Protocol (LMP) Test Messages
RFC 4207

Document Type RFC - Proposed Standard (October 2005; Errata)
Updated by RFC 6898
Authors Dimitri Papadimitriou  , Jonathan Lang 
Last updated 2020-01-21
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Network Working Group                                            J. Lang
Request for Comments: 4207                                   Sonos, Inc.
Category: Standards Track                               D. Papadimitriou
                                                            October 2005

Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy (SDH)
       Encoding for Link Management Protocol (LMP) Test Messages

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 (2005).


   This document details the Synchronous Optical Network
   (SONET)/Synchronous Digital Hierarchy (SDH) technology-specific
   information needed when sending Link Management Protocol (LMP) test

1.  Introduction

   For scalability purposes, multiple physical resources that
   interconnect Label Switching Routers (LSRs) can be combined to form a
   single traffic engineering (TE) link for the purposes of path
   computation and signaling.  These resources may represent one or more
   physical links that connect the LSRs, or they may represent a Label
   Switched Path (LSP) if LSP hierarchy [RFC4206] is used.  The
   management of TE links is not restricted to in-band messaging, but
   instead can be done using out-of-band techniques.

   The Link Management Protocol (LMP) [RFC4204] has been developed as
   part of the Generalized MPLS (GMPLS) protocol suite to manage TE
   links.  LMP currently consists of four main procedures, of which the
   first two are mandatory and the last two are optional:

Lang & Papadimitriou        Standards Track                     [Page 1]
RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005

      1.  Control channel management
      2.  Link property correlation
      3.  Link verification
      4.  Fault management

   Control channel management is used to establish and maintain control
   channel connectivity between adjacent nodes.  This is done using a
   Config message exchange followed by a lightweight keep-alive message
   exchange.  Link property correlation is used to aggregate multiple
   data links into a single TE Link and to synchronize the link
   properties.  Link verification is used to verify the physical
   connectivity of the data links and to exchange the Interface_Ids of
   the data links.  Fault management is primarily used to suppress
   alarms and to localize failures in both opaque and transparent
   networks.  When LMP is used with SONET/SDH, however, the fault
   management procedures may not be needed as existing SONET/SDH
   mechanisms can be used.

   In this document, the SONET/SDH technology-specific information for
   LMP is defined.  Specifically, the SONET/SDH test procedures used for
   link verification and link property correlation are detailed.  These
   procedures include the trace correlation transport mechanism (defined
   for J0, J1, J2) that supports a separation of the transport and
   control plane identifiers.  The latter procedure requires a new trace
   monitoring function that is discussed in this document.  Once the
   data links have been verified, they can be grouped to form TE links.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

   The reader is assumed to be familiar with the terminology in
   [RFC4204], [G.707], and [T1.105].  The following abbreviations are
   used in this document:

   CRC-N:   Cyclic Redundancy Check-N.
   DCC:     Data communications channel.
   LOVC:    Lower-order virtual container.
   HOVC:    Higher-order virtual container.
   MS:      Multiplex section.
   MSOH:    Multiplex section overhead.
   POH:     Path overhead.
   RS:      Regenerator section.
   RSOH:    Regenerator section overhead.
   SDH:     Synchronous digital hierarchy.
   SOH:     Section overhead.

Lang & Papadimitriou        Standards Track                     [Page 2]
RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005

   SONET:   Synchronous Optical Network.
   STM(-N): Synchronous Transport Module (-N) (SDH).
   STS(-N): Synchronous Transport Signal-Level N (SONET).
   VC-n:    Virtual Container-n (SDH).
   VTn:     Virtual Tributary-n (SONET).

3.  Verifying Link Connectivity

   In [RFC4204], a link verification procedure is defined whereby Test
   messages are transmitted in-band over the data links.  This is used
   for data plane discovery, Interface_Id exchange (Interface_Ids are
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