A kind of topology aggregation algorithm in hierarchical wavelength-routed optical networks

In large-scale networks composed of several hierarchical subnetworks, topology aggregation (TA) is implemented for both scalability and security consideration. However, due to the special characteristic of optical wavelength-routed networks, existing TA algorithms cannot be applied directly for topology compression. In this paper, we propose a kind of TA algorithm suitable for hierarchical wavelength-routed optical networks, thereby considering information of residual wavelengths on network links. Basically, our TA algorithm is based on a transition matrix technique for constructing a full mesh topology and asymmetric star approach for a more compact topology. Simulations with randomly-generated networks show that topology information compression can be achieved with a little loss of its accuracy: the ratio of border node pairs with representation deviation being well below 10%. Results also indicate that the advantage of our algorithm is also behaved on reducing the amount of link-state-advertisement (LSA) messages and making networks less vulnerable to propagation delay of these messages over communication links.