RFC 3612 (rfc3612) - Page 1 of 16
Applicability Statement for Restart Mechanisms for the Label Distribution Protocol (LDP)
Alternative Format: Original Text Document
Network Working Group A. Farrel
Request for Comments: 3612 Old Dog Consulting
Category: Informational September 2003
Applicability Statement for Restart Mechanisms
for the Label Distribution Protocol (LDP)
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 (2003). All Rights Reserved.
Abstract
This document provides guidance on when it is advisable to implement
some form of Label Distribution Protocol (LDP) restart mechanism and
which approach might be more suitable. The issues and extensions
described in this document are equally applicable to RFC 3212,
"Constraint-Based LSP Setup Using LDP".
1. Introduction
Multiprotocol Label Switching (MPLS) systems are used in core
networks where system downtime must be kept to a minimum. Similarly,
where MPLS is at the network edges (e.g., in Provider Edge (PE)
routers) [RFC 2547], system downtime must also be kept to a minimum.
Many MPLS Label Switching Routers (LSRs) may, therefore, exploit
Fault Tolerant (FT) hardware or software to provide high availability
of the core networks.
The details of how FT is achieved for the various components of an FT
LSR, including the switching hardware and the TCP stack, are
implementation specific. How the software module itself chooses to
implement FT for the state created by the LDP is also implementation
specific. However, there are several issues in the LDP specification
[RFC 3036] that make it difficult to implement an FT LSR using the LDP
protocols without some extensions to those protocols.
Proposals have been made in [RFC 3478] and [RFC 3479] to address these
issues.
Farrel Informational
