U-turn Alternates for IP/LDP Fast-Reroute

Document Type Expired Internet-Draft (individual)
Author Alia Atlas 
Last updated 2006-03-07
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This document defines and describes the use of U-turn alternates to provide local protection for IP unicast and/or LDP traffic in the event of a single failure, whether link, node or shared risk link group (SRLG). When a topology change occurs, a router S pre-computes for each prefix an alternate next-hop that can be used if the primary next-hop fails. An acceptable alternate can be either a loop-free alternate or a U-turn alternate. A U-turn alternate uses a neighbor, whose primary next-hop to the prefix is router S itself and which has itself a loop-free node-protecting alternate, which thus does not go through router S to reach the destination prefix.


Alia Atlas (akatlas@google.com)

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