Optimization of p-Cycle Protection in Mixed Line Rate WDM Networks with Limited Transmission Reaches

We consider the problem of routing and rate assignment with p-cycle protection for mixed line rate (MLR) networks that are limited by transmission reaches. The problem is formulated mathematically as integer linear programming (ILP) problems under two different assumptions. First, we consider using each p-cycle to protect working lightpaths at common fixed line rate, and refers to this case as the fixed cycle rate (FCR) approach. We then perform comparative study between the FCR approach and the mixed cycle rate (MCR) approach, which is the second case and allows each p-cycle to protect working lightpaths with various rates. The objective of each ILP problem is to minimize the overall cost function, which consists of transponder operating cost, as primary costs and p-cycle operating costs, as secondary costs. Number results show that the MCR approach yields lower cost and is more efficient as the traffic increase when compared the FCR approach. In addition, we compare the use of MLR networks to the use of single line rate (SLR) networks to verify that MLR networks yield lower costs.