Research On Integrated Routing Policies In IP/MPLS Over WDM Network

IP technology offers high flexibility and intelligence, and WDM provides unprecedented levels of bandwidth scalability, so the application and development of IP over WDM is imperative. Due to its excellent functions such as QoS and TE, together with GMPLS's powerful routing and signaling functions and the implementation in the unified control plane, MPLS technology is expected to be chosen as the adaptation layer in the integration of IP and WDM, and such network is called IP/MPLS over WDM network.According to the integration difference of control plane, IP/MPLS over WDM network is classified as follows: the overlay model with separated routing scheme and the peer model with integrated routing scheme. The peer model employs a unified control plane, so it can achieve better resource utilization, and will be the ultimate aim of IP/MPLS over WDM network. Thus, in this paper, integrated routing policies for the peer model will be discussed. Based on the layered graph model derived from the network model, three integrated routing policies are compared: MTA, IOLF and LHLB(Least Hop and Load Balance policy). By comparing the load balance parameter of each path, the LHLB policy chooses the path that has fewer hops and more residual bandwidth, which can distribute the whole traffic load within the network evenly to each link, so it has better blocking performance. Then the virtual link selection problem that how to select a suitable virtual link between two nodes to route LSP is discussed, and three policies are compared. At last, by comparing MTA policy for the integrated routing with ILF policy for the separated routing, it is proved that the integrated routing policy has better blocking performance and higher utilization of network resources than the separated routing policy.