The two most important objectives for network operation are:

1. (i) capacity minimization

2. (ii) revenue maximization.

For capacity minimization, there are three operational phases in survivable WDM network operation: (i) initial call setup, (ii) short-/medium-term reconfiguration, and (iii) long-term reconfiguration. All three optimization problems may be modeled using an ILP formulation separately. A single ILP formulation that can incorporate all three phases of the network operation is presented in this chapter. This common framework also takes service disruption into consideration. Typically, most of the design problems in optical networks have considered a static traffic demand and have tried to optimize the network cost assuming various cost models and survivability paradigms. Fast restoration is a key feature addressed in the designs. Once the network is provisioned, the critical issue is how to operate the network in such a way that the network performance is optimized under dynamic traffic.

The framework for revenue maximization is modified to include a service differentiation model based on lightpath protection. A multi-stage solution methodology is developed to solve individual service classes sequentially and to combine them to obtain a feasible solution. Different cost comparisons in terms of the increase in revenue obtained for various service classes with the base case of accepting demands without any protection show the gains of planning and operation efficiency.

Capacity minimization

Among the three phases of capacity minimization the initial call setup phase is a static optimization problem where the network capacity is optimized for the given topology and the traffic matrix to be provisioned on the network.