Fault Tolerant Routing in Star Graphs Using Fault Vector

Abstract

In this paper a fault tolerant routing algorithm for unicasting on star graph is proposed. The routing algorithm does not involve back tracking and uses fault-vectors. Each node in an n-star has a fault-vector of $\lfloor\frac{3(n-1)}{2}\rfloor$ bits. The kth bit of a node’s fault-vector is a measure of its routing ability to nodes which are at distance k from itself. The fault-vector of each node can easily be calculated through $\lfloor\frac{3(n-1)}{2}\rfloor$ rounds of information exchanges among neighbor nodes. For a given source destination pair (u,v), the routing algorithm finds a path of length d + h where d is the length of the shortest path between u and v in a fault-free star graph and h = 0, 2 or 4. The space requirement for storing the fault vector is O(n) in each node. Simulation results show that the proposed algorithm far outperforms the routing algorithm based on safety vectors [13].