THE HOP-LIMIT APPROACH FOR SPARE-CAPACITY ASSIGNMENT IN SURVIVABLE NETWORKS

This paper presents a new approach for spare-capacity assignment in me sh-type self healing networks which use reconfigurable network element s as transmission hubs, Under this approach the process of reducing to tal weighted cost of spare capacity is obtained by taking into account all network's eligible restoration routes which do not violate a pred etermined hop limit value, The process derived considers a given set o f possible failure scenarios, which include single-link, multi-link an d node failures, and is adaptive to accommodate several practical cons iderations such as integrality of spare channels and modularity of tra nsmission systems, This process is generally composed of two parts: Pa rt 1 relies on a linear-programming formulation (Min-Max) from which a lower bound solution of spare cost is found; Part 2 rounds-up the sol ution of Part 1 to a feasible solution and uses a series of Max-Flow t ests aimed at tightening the rounded-up assignment to a practical opti mum, For small and moderate size networks a Mixed-Integer-Programming formulation of Part 1 can be used to obtain optimal results, A network , which has already been studied in the Literature, is analyzed to ill ustrate the approach developed and to demonstrate, for cases where hop limits can feasibly be kept low, its superiority over other algorithm s published in this area.