A comparative study of restoration schemes and spare capacity assignments in mesh networks

This paper presents the results of a comparative study of spare capacity assignment for original quasi-path restoration (OQPR), improved quasi-path restoration (IQPR), link restoration (LR), path restoration (PR) and link-disjoint path restoration (LDPR) schemes. Numerical results indicate that the restoration schemes studied can be sorted from most expensive to least expensive (spare capacity assignment cost) in the following order: LR, OQPR, IQPR, LDPR and PR. Since IQPR is computationally very efficient, simpler than PR, scalable, and economical in spare capacity assignment, it provides a good alternative to PR when quick restoration is desired. However, due to the potential difficulty in rapid failure isolation coupled with the increasing importance of restoration speed and simplicity, LDPR is an attractive scheme. A number of networks with different topologies and projected traffic demand patterns are used in the experiments to study the effect of various network parameters on spare capacity assignment cost. The experimental analysis shows that network topology, demand patterns and the average number of hops per primary route have a significant impact on the spare capacity assignment cost savings offered by one scheme over the other.