Routing and wavelength assignment with crankback re-routing extensions by means of ant colony optimization

Crankback re-routing extensions can offer significant improvements in the successful setup of Label Switched Paths (LSPs) by allowing new retries on alternate paths that circumvent blocked links or nodes. These extensions can be incorporated into a fully-distributed algorithm based on Ant Colony Optimization metaheuristics, taking advantage of its self-adapting, emergent behavior. By comparing with traditional fixed-alternate re-routing mechanisms, simulations have demonstrated that the proposed algorithm can efficiently mitigate lightpath blocking, both during normal operation and in case of network failure, by locally repairing failed LSP setups due to blocked/failed resources.