On the effectiveness of restoration path computation methods

We compare the effectiveness of distributed restoration path computation methods that use head-end precomputation and do not use backup path sharing. Our aim is to provide statistics on primary and secondary path lengths of simple disjoint path computation methods in real-world network topologies. Moreover, we propose a path computation method which can be used when paths are precomputed, but not preestablished. The benefit of this new method is that it intends to select strictly the shortest paths for the working path and for the restoration path as well. We allow common links between the two paths, therefore an additional restoration path is needed. By minimizing the number of common edges between the working and the shortest backup path, our method maximizes the probability that, in the case of a link failure, the shortest backup path can be used for restoration. In the case that the restoration path is a shortest path, it is not necessary to revert to the original working path after the failed link is restored, instead, sub-optimal paths can be re-optimized in the network in order to balance traffic load.