Benefits of p-cycles in a mixed protection and restoration approach

There are reasons to expect that the protection switching times of p-cycles will allow them to be considered for protecting services where previously only 1+1 automatic protection switching would have been specified, for the highest speed. Here we introduce p-cycles as an option in a mixed-method environment to protect demands that do not strictly require dedicated 1+1 APS, but need a faster switching time than provided by shared backup path protection. Results show that in a mixed services environment, realizing such demands with p-cycles rather than 1+1 APS can produce a significant capacity saving. To further explore the potential of mixed-method design, we also test an approach where individual demands are not strictly assigned to be realized by a particular method. Instead, each path may be protected with any method that gives the minimum required service guarantee, but where possible or advantageous in the overall design, paths can be protected by an even faster method than required. For instance, a requirement for 200 ms, usually served by an SBPP realization, may (selectively) be realized instead with p-cycle protection at 80 ms. This optimization of the protection method selection produces a small further capacity savings, but provides a remarkable increase in the number of service paths that enjoy faster protection than strictly required by their class of service specification. When modularity is included, this new design approach provides even greater improvement in protection quality.