Computing All the Best Swap Edges Distributively

Recently great attention has been given to {\em point-of-failure swap rerouting}, an efficient technique for routing in presence of transient failures. According to this technique, a message follows the normal routing table information unless the next hop has failed; in this case, it is redirected towards a precomputed link, called {\em swap}; once this link has been crossed, normal routing is resumed. The amount of precomputed information required in addition to the routing table is rather small: a single link per each destination. Several efficient serial algorithms have been presented to compute this information; none of them can unfortunately be efficiently implemented in a distributed environment. In this paper we present protocols, based on a new strategy, that allow the efficient computation of all the optimal swap edges under several optimization criteria.