A new Request for Comments is now available in online RFC libraries.
RFC 4920
Title: Crankback Signaling Extensions for MPLS
and GMPLS RSVP-TE
Author: A. Farrel, Ed.,
A. Satyanarayana, A. Iwata,
N. Fujita, G. Ash
Status: Standards Track
Date: July 2007
Mailbox: adrian@olddog.co.uk,
asatyana@cisco.com,
a-iwata@ah.jp.nec.com, n-fujita@bk.jp.nec.com,
gash5107@yahoo.com
Pages: 38
Characters: 88679
Updates/Obsoletes/SeeAlso: None
I-D Tag: draft-ietf-ccamp-crankback-06.txt
URL: http://www.rfc-editor.org/rfc/rfc4920.txt
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information used to compute a path may be out of date.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 recovery 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", RFC 3209, and GMPLS signaling as defined in "Generalized
Multi-Protocol Label Switching (GMPLS) Signaling Functional
Description", RFC 3473. 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. [STANDARDS TRACK]
This document is a product of the Common Control and Measurement Plane
Working Group of the IETF.
This is now a Proposed Standard Protocol.
STANDARDS TRACK: This document specifies an Internet standards track
protocol for the Internet community,and requests discussion and suggestions
for improvements.Please refer to the current edition of the Internet
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