LIBRA: a distributed routing algorithm for large internets

The loop-identification-and-blocking routing algorithm (LIBRA) is introduced for the distributed maintenance of routing information in large internets. According to LIBRA, each node maintains a routing table; each entry in this table contains the length of and next node in the chosen path to each destination, and a path label. Update messages contain a list of updates; each such update specifies the destination node, the length of the selected path, and its path label. A path label consists of a list of node identifiers used to identify and block a loop before it is used for routing. LIBRA is shown to converge in a finite time after an arbitrary sequence of link-cost or topological changes and to be loop-free at every instant, with no need for internodal coordination spanning more than one hop, or the specification or computation of complete paths from source to destination. LIBRA's performance is shown to be better than the performance of other routing algorithms previously proposed or currently used in network and internet routing protocols.<>