Internet Engineering Task Force (IETF) D. Beller
Request for Comments: 5718 Alcatel-Lucent
Category: Standards Track A. Farrel
ISSN: 2070-1721 Old Dog Consulting
An In-Band Data Communication Network For the MPLS Transport Profile
The Generic Associated Channel (G-ACh) has been defined as a
generalization of the pseudowire (PW) associated control channel to
enable the realization of a control/communication channel that is
associated with Multiprotocol Label Switching (MPLS) Label Switched
Paths (LSPs), MPLS PWs, MPLS LSP segments, and MPLS sections between
adjacent MPLS-capable devices.
The MPLS Transport Profile (MPLS-TP) is a profile of the MPLS
architecture that identifies elements of the MPLS toolkit that may be
combined to build a carrier-grade packet transport network based on
MPLS packet switching technology.
This document describes how the G-ACh may be used to provide the
infrastructure that forms part of the Management Communication
Network (MCN) and a Signaling Communication Network (SCN).
Collectively, the MCN and SCN may be referred to as the Data
Communication Network (DCN). This document explains how MCN and SCN
messages are encapsulated, carried on the G-ACh, and demultiplexed
for delivery to the management or signaling/routing control plane
components on an MPLS-TP node.
Status of This Memo
This is an Internet Standards Track document.
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). Further information on
Internet Standards is available in 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
Beller & Farrel Standards Track [Page 1]RFC 5718 DCN for MPLS Transport Profile January 2010Copyright Notice
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The associated channel header (ACH) is specified in [RFC4385]. It is
a packet header format for use on pseudowires (PWs) in order to
identify packets used for Operations, Administration, and Maintenance
(OAM) and similar functions.
The use of the ACH is generalized in [RFC5586] and can be applied on
any Multiprotocol Label Switching (MPLS) Label Switching Path (LSP).
This is referred to as the Generic Associated Channel (G-ACh) and is
intended to create a control/management communication channel
associated with the LSP that can be used to carry packets used for
OAM and similar functions (e.g., control/management plane messages).
The purpose of a packet carried on the G-ACh is indicated by the
value carried by the Channel Type field of the ACH and a registry of
values is maintained by IANA ([RFC4446] and [RFC4385]). The ACH is
referred to in this document as the G-ACh header.
The MPLS transport profile (MPLS-TP) is described in [MPLS-TP] and in
[RFC5654]. MPLS-TP is the application of MPLS to construct a packet
transport network. It constitutes a profile of MPLS that enables
operational models typical in transport networks, which includes
additional OAM, survivability, and other maintenance functions not
previously supported by MPLS.
Label Switching Routers (LSRs) in MPLS networks may be operated using
management protocols or control plane protocols. Messaging in these
protocols is normally achieved using IP packets exchanged over IP-
capable interfaces. However, some nodes in MPLS-TP networks may be
constructed without support for direct IP encapsulation on their
line-side interfaces and without access to an out-of-fiber data
Beller & Farrel Standards Track [Page 2]