Using performability in the design of communication networks

Conventional network design techniques treat the concepts of performance and reliability separately. This approach ensures that reliability requirements are met and performance specifications are satisfied when all components are operational. However, it does not guarantee a graceful degradation of the performance of the network under conditions of failure. In order to derive a fault-tolerant network, it is necessary to design the network with respect to a combined measure of performance and reliability. Such a measure originated in the early 1980s and is referred to as performability. The authors propose a technique that uses performability in the design of communication networks, with the objective of deriving a design methodology for fault-tolerant networks. The benefits of using this approach, compared with conventional design methods, are illustrated by means of a design example.