Convergent Multi-Path Routing

We present a protocol for maintaining multiple paths to each destination in a network of processes. For each destination, each process in the network maintains a set of neighbors which are used as next-hops to reach the destination. This set is known as the successor set. Collectively, the successor sets from all processes in the network with respect to a given destination form a spanning, directed, and acyclic graph, whose only sink is the given destination. The protocol we present has two interesting properties. First, the graph is maintained acyclic at all times, even though the successor set is dynamic. Second, the protocol tolerates all types of transient faults, even those which may not be detected. Therefore, if the protocol is started from an arbitrary initial state, it will converge to a normal operating state in which a spanning, directed, and acyclic graph is obtained and subsequently maintained.