Delay sensitive routing in PNNI-based ATM networks

We propose an enhanced path selection algorithm for ATM networks that implement the private network-node interface (PNNI) v1.0 standard. Our enhancement stems from the fact that we consider delay in determining the appropriate route for an ATM call. The paper presents two new path selection algorithms based on two different delay accumulation methods, namely the simple (additive) method, and the asymptotic method. The delay based path selection algorithm is achieved by adopting a constrained shortest path algorithm which optimizes two metrics simultaneously in contrast to Dijkstra's algorithm that optimizes only one. The execution times of these two algorithms are also compared and quantified based on the results of an experimental study. Using an analytical model we demonstrate the performance gain by adopting a delay-based routing procedure in simple network configurations in terms of the number of crankbacks. Our network configurations and traffic loading patterns showed that up to 36% less crankbacks can be obtained when adopting a delay-sensitive routing scheme as opposed to a simple shortest-path algorithm.