Adaptive routing based on summary information mitigates the adverse impact of outdated control messages

Adaptive routing is considered as a promising solution to support flexible resource allocation in wavelength division multiplexing network. Resource advertisement protocols, such as link state advertisement (LSA), are essential to enable routing algorithms to efficiently carry out the required path computation. The LSA nonnegligible convergence time may lead to outdated link information, which in turns may adversely affect the efficiency of the computed path. As a result, traffic engineering is suboptimal and some services may be unnecessarily blocked. This study investigates the impact of outdated information on the blocking probability of adaptive routing schemes focusing on two LSA protocols: one advertising specific resource information and one advertising only a summary of the same. Our simulation results show that compared with the routing scheme requiring specific information LSA, the approach based on LSA with summary information is by its nature not precise and hence able to mitigate the adverse impact of the LSA convergence time on blocking performance.