Optimising multiple aspects of network survivability

It is generally accepted that survivable networks tend to consist of network elements (nodes and links) where no individual element is significantly more important than any other element. Using a traffic based network survivability metric Si, which quantifies the impact of removing network element i from a network of N elements, this paper investigates the modification of link capacities to simultaneously maximise average network survivability (1/N/spl Sigma//sub i=1//sup N/S/sub i/) and minimise the variability of Si (var(Si)). For some networks there appears to be an unique optimal set of link capacities however, for others, a number of possible optima exist. For these networks a Pareto-optimal set was generated so that a decision could be made on which link enhancements should be performed. The change in optima as a consequence of changes in the budget for link enhancements and also in changes in the required network traffic load were also investigated.