A new path metric for survivable circuit switched routing

The authors report a novel path metric for survivable circuit switched routing. The distribution of physical assets in the network is assumed flat, and the network operates in a stressed environment with link and node failures. In addition, the traffic distribution is arbitrary as a function of space and time. The fundamental assumption driving this work is that `delay´, both processing delay at a node and propagation delay, is insignificant to the degree that from a delay-only viewpoint, the total number of hops that comprise the path of the circuit is unimportant. A heuristic that attempts to completely avoid using capacity into or out of a node and generally defers blocking calls as long as possible is used. Three metrics have been studied: the shortest number of hops without regard for link utilization, the shortest number of hops considering links that have unused capacity, and a nonlinear utilization-sensitive metric