Fault-tolerant hierarchical routing

This paper presents a self-stabilizing, fault-tolerant hierarchical routing algorithm. Hierarchical routing algorithms are less expensive algorithm than traditional all-pairs routing algorithms (i.e., lower memory requirements, faster routing table lookups, and less costly broadcast). The algorithm presented here retains these benefits yet, maintains routing capability between all pairs of connected nodes, even in the presence of faults, such as link/node failures and repairs and corruption of program variables. Additionally, this algorithm solves the problem of area partition where nodes that are defined to be in the same subset of the network become isolated by link or node failure. Being self-stabilizing, starting from an arbitrary state the protocol is guaranteed to reach a configuration with routing tables containing valid entries in a finite time. The protocol automatically updates the shortest paths in the face of dynamically changing link weights. The protocol dynamically allocates/deallocates storage for the routing information as the network size changes. The algorithm works on an arbitrary topology and under a distributed daemon model.