Integrated routing in GMPLS-based IP/WDM networks

The Internet traffic evolution has forced network operators to migrate toward an integrated infrastructure which brings the IP and optical layers under a unified model. The integration between the two technologies has been facilitated by the development of the Generalized Multi Protocol Label Switching. In the integrated scenario, Multilayer Traffic Engineering can be reinforced with integrated routing techniques. Integrated IP/WDM routing facilitates the routing decision phase by allowing a node to have a complete knowledge of the IP and WDM domains when accommodating traffic. This study focuses on integrated IP/WDM routing. We analyze two basic policies widely discussed in literature: one policy prioritizes the traffic accommodation on the virtual topology, while the other prioritizes the traffic accommodation on the physical topology. We show that both the mechanisms do not lead to efficient resource utilization because they tend to congest one layer more than the other one. We propose an adaptive heuristic which combines the advantages of both the policies. When accommodating traffic, the proposed approach selects the appropriate layer depending on the resource utilization being experienced in the virtual and the physical topologies. We demonstrate via simulations that the cross-layer resource optimization executed by the proposed scheme achieves significant improvements in terms of blocking ratio.