Network Working Group J. Lang
Request for Comments: 4207 Sonos, Inc.
Category: Standards Track D. Papadimitriou
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 (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
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.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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).