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Status:

INFORMATIONAL

Authors:

M. Shand
S. Bryant
S. Previdi
C. Filsfils
P. Francois
O. Bonaventure

Stream:

IETF

Source:

rtgwg (rtg)

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DOI:  https://doi.org/10.17487/RFC6976

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Abstract

This document describes an illustrative framework of a mechanism foruse in conjunction with link-state routing protocols that preventsthe transient loops that would otherwise occur during topologychanges. It does this by correctly sequencing the forwardinginformation base (FIB) updates on the routers.

This mechanism can be used in the case of non-urgent (managementaction) link or node shutdowns and restarts or link metric changes.It can also be used in conjunction with a fast reroute mechanism thatconverts a sudden link or node failure into a non-urgent topologychange. This is possible where a complete repair path is providedfor all affected destinations.

After a non-urgent topology change, each router computes a rank thatdefines the time at which it can safely update its FIB. A method foraccelerating this loop-free convergence process by the use ofcompletion messages is also described.

The technology described in this document has been subject toextensive simulation using pathological convergence behavior and realnetwork topologies and costs. However, the mechanisms described inthis document are purely illustrative of the general approach and donot constitute a protocol specification. This document represents asnapshot of the work of the Routing Area Working Group at the time ofpublication and is published as a document of record. Further workis needed before implementation or deployment.

For the definition ofStatus,seeRFC 2026.

For the definition ofStream, seeRFC 8729.