Revisiting p-Cycles / FIPP p-Cycles vs. Shared Link / Path Protection

While the advantages of p-cycles and FIPP p-cycles are well established, there has been no systematic analysis of how much bandwidth they consume in comparison with the shared link or path protection schemes. It was also recently observed that, even enumerating a huge number of cycles is not necessarily a guarantee for obtaining good quality solutions with the classical ILP models if tools for large scale programming such as, e.g., column generation techniques, are not used. For instance, a reduction of up to 37% of the solution cost for FIPP p-cycles can be obtained when using column generation instead of classical ILP modeling. We propose to investigate the bandwidth protection costs of p-cycles and FIPP p-cycles in comparison with those of shared link and path protection, using column generation models for the four protection schemes, and therefore obtaining the optimal values for all of them, out of any doubt. Accurate quantitative comparisons show that the average excess required bandwidth is about 6.6% for p-cycles and about 13.4% for FIPP p-cycles in exchange of a much faster restoration time.