Using Path Identifiers for Efficient Loop-Free Routing in Computer Networks

A new family of algorithms for loop-free routing over multiple paths based on path identifiers is introduced. It is shown that different types of path identifiers can be used to attain loop-free routing if total ordering is established among such identifiers. A path identifier can range from the path itself to a succinct representation of it that need not be unique. POLAR (Path-Ordered Loop-free Algorithm for Routing) is presented as an example in which each router labels its shortest distance to each destination with a path identifier consisting of the number of hops and the identifier of the second-to-last hop along its least preferred loop-free path to that destination. POLAR is shown to converge to shortest paths without ever creating loops, and to be able to converge faster than routing protocols like OSPF depending on the type of topology changes taking place in a network.