Reroute sequence planning for protected traffic flows in GMPLS networks

This paper aims the solution of the reroute sequence planning problem for protected traffic flows. This problem arises when a service provider recalculates the path set by a global optimization tool in order to achieve a better resource utilization. In this case a sequence of the one-by-one reconfiguration of the traffic flows from their original paths to the optimized paths has to be found, with the constraint that the link capacities should not be violated at any time during the rerouting process. This optimization problem is related to discrepancy theory and it is NP-complete. It is computationally hard in realworld situations because of the large amount of routers and traffic flows in the network, therefore exact and approximation algorithms have little practical relevance. We present a number of heuristic approaches, which are tested on various network situations. We assume generalized multi-protocol label switching context but the methods can be applied for other types of networks as well. The results show that in most cases these methods are appropriate for calculating the reroute sequence, mainly when the objective of the path optimization is load balancing.