Spare Capacity Allocation for Non-Linear Link Cost and Failure-Dependent Path Restoration

The design of survivable mesh based communication networks has received considerable attention in recent years. One task is to route backup paths and allocate spare capacity in the network to guarantee seamless communications services survivable to a set of failure scenarios. This is a complex multi-constraint optimization problem, called spare capacity allocation (SCA). This paper presents a matrix based model for the NP-complete SCA problem on directed networks and develops an approximation algorithm, termed successive survivable routing (SSR) to include non-linear capacity cost and failure-dependent path restoration. The SCA problem using a modular link cost function is studied using SSR. Numerical results of total spare capacity and total cost are compared showing that SSR finds solutions with lower total costs when a non-linear cost function is considered. Moreover, the SCA problem using failure-dependent path restoration, which finds multiple backup paths for each working path, is discussed. A numerical comparison among different path restoration schemes using SSR is given showing the tradeoffs. Keywords—spare capacity allocation, protection and restoration algorithms, network survivability, survivable routing