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Applicability Statement for Restart Mechanisms for the Label Distribution Protocol

Document Type Expired Internet-Draft (individual)
Expired & archived
Author Adrian Farrel
Last updated 2002-10-14
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date (None)
Responsible AD (None)
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


Multiprotocol Label Switching (MPLS) systems will be used in core networks where system downtime must be kept to a minimum. Similarly, where MPLS is at the network edges (for example, in Provider Edge routers) system downtime must also be kept as small as possible. 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 Label Distribution Protocol (LDP) is also implementation specific but there are several issues in the LDP specification in RFC 3036 'LDP Specification' that make it difficult to implement an FT LSR using the LDP protocols without some extensions to those protocols. Proposals have been made in 'Fault Tolerance for the Label Distribution Protocol (LDP)' [LDP-FT] and 'Graceful Restart Mechanism for LDP' [LDP-RESTART] to address these issues. This document gives guidance on when it is advisable to implement some form of LDP restart mechanism and which approach might be more suitable. The issues and extensions described here are equally applicable to RFC 3212, 'Constraint-Based LSP Setup Using LDP' (CR-LDP).


Adrian Farrel

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)