Reconfiguration of spanning trees in networks in the presence of node failures

Connectivity among a set of user entities in a network can be provided by a network level abstraction of an acyclic graph (or spanning tree). The authors discuss the reconfiguration of a graph in the presence of failures of network nodes. A reconfiguration manifests itself as a graph fragmentation problem, whereby two or more disjoint subgraphs attempt to connect with one another to form a composite graph. Fragment interconnection requires contention resolution between fragments to avoid cycles. Two classes of contention resolution algorithms applicable for environments with a potentially large number of fragments are presented. They are based on preestablished ranking among fragments and random arbitration among fragments. The algorithms have been evaluated by simulation and compared. The algorithms are useful in supporting data multicasting across workstations and distributed computations involving data on different machines