Stability of p-Cycles under Dynamic Traffic

p-Cycles offer a protection that corresponds to an efficient pre-configured and pre-cross-connected protection scheme. Thereafter, we study the stability and the efficient reconfiguration of p-cycles in the context of dynamic asymmetric traffic. The literature acknowledges it as a difficult problem, but which is of paramount importance in the selection of p-cycles as a protection scheme in Intelligent Optical Networks (IONs). We investigate two p-cycle updating models which differ mainly by their objective criteria. The first objective is the classical one, aiming at minimizing the spare capacity. The second one is new and corresponds to the number of pre-cross-connections that needs to be set/reset after each traffic variation, while attempting to maximize the re-use of previously established pre-cross-connection settings in spite of the modifications of the p-cycles. Note that the second model needs to explicitly include wavelength continuity constraints and is therefore slightly more complex. Results show that: (i) The proposed ILP tools are scalable, and (ii) While p-cycles appear not to be very stable with the first criterion, they emerge as highly stable with the second criterion.