Subject: Protocol Action: Fault Tolerance for the Label Distribution Protocol (LDP) to Proposed Standard

From: The IESG <[email-masked]>
Date: Tue, 10 Dec 2002 19:52:52 -0500

The IESG has approved the Internet-Draft 'Fault Tolerance for the Label
Distribution Protocol (LDP)' <draft-ietf-mpls-ldp-ft-06.txt> as a 
Proposed Standard. This document is the product of the Multiprotocol 
Label Switching Working Group. The IESG contact persons are Scott 
Bradner and Bert Wijnen.

Technical Summary

Multiprotocol Label Switching (MPLS) systems will be used in core 
networks where system downtime must be kept to an absolute 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 Label Distribution Protocol (LDP), the switching hardware 
and TCP, are implementation specific. This document identifies issues in 
the LDP specification in RFC 3036 "LDP Specification" that make it 
difficult to implement an FT LSR using the current LDP protocols, and 
defines enhancements to the LDP specification to ease such FT LSR 
implementations.

The issues and extensions described here are equally applicable to RFC
3212, "Constraint-Based LSP Setup Using LDP".

Working Group Summary

The mpls working group supported publication of this document.

Protocol Quality

This document was reviewed for the IESG by Scott Bradner.

RFC-Editor:

       This IESG Note goes at the start of the document:

           IESG Note: This specification includes procedures for
           failure detection and failover for a TCP connection
           carrying MPLS LDP control traffic. It is limited to that
           application, and does not provide a general approach for 
	     using TCP connections with applications requiring fault 
	     tolerance. The specification lacks guidance for timer and 
	     retry value choices. The specification should not serve 
	     as a model for TCP fault tolerance design for any future 
	     document, and any user is advised to test any configuration 
	     based on this specification very carefully for problems 
	     such as premature failovers.