Design and performance issues of protection virtual path networks

This paper addresses the problem of allocating protection Virtual Path (VP) routes in an ATM network to enable rapid restoration from span or node failures. It is shown how the minimisation of one resource, spare capacity, comes at the expense of another, the number of redundant Virtual Path Identifiers (VPIs). Furthermore, because spare capacity reduction is achieved by allowing longer backup path routes in terms of the number of links used, performance issues related to delay and reliability become increasingly important. After formulating appropriate design and performance metrics pertaining to a protection VP network design, it is illustrated how they are traded off in a design space where spare capacity minimisation is performed.