I-D ACTION:draft-ietf-ccamp-crankback-04.txt

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This draft is a work item of the Common Control and Measurement Plane Working Group of the IETF.

	Title		: Crankback Signaling Extensions for MPLS and GMPLS Signaling
	Author(s)	: A. Farrel, et al.
	Filename	: draft-ietf-ccamp-crankback-04.txt
	Pages		: 34
	Date		: 2005-2-21
	
In a distributed, constraint-based routing environment, the
   information used to compute a path may be out of date. This means
   that Multiprotocol Label Switching (MPLS) and Generalized MPLS
   (GMPLS) Traffic Engineered (TE) Label Switched Path (LSP) setup
   requests may be blocked by links or nodes without sufficient
   resources. Crankback is a scheme whereby setup failure information is
   returned from the point of failure to allow new setup attempts to be
   made avoiding the blocked resources. Crankback can also be applied to
   LSP restoration to indicate the location of the failed link or node.
   This document specifies crankback signaling extensions for use in
   MPLS signaling using RSVP-TE as defined in 'RSVP-TE: Extensions to
   RSVP for LSP Tunnels', RFC3209, and GMPLS signaling as defined in
   'Generalized Multi-Protocol Label Switching (GMPLS) Signaling
   Functional Description', RFC3473. These extensions mean that the LSP
   setup request can be retried on an alternate path that detours around
   blocked links or nodes. This offers significant improvements in the
   successful setup and recovery ratios for LSPs, especially in
   situations where a large number of setup requests are triggered at
   the same time.

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