LSP protection for delay-differentiated dynamic traffic in IP-over-WDM networks with port constraints

We consider the problem of label switched path (LSP) protection for dynamic traffic with differentiated delay requirements in IP-over-WDM networks with limited port resources. A pair of link-disjoint primary LSP and backup LSP is provided for each connection to enable guaranteed and timely recovery in the event of a single link failure. To support delay sensitive traffic such as voice, the primary and backup LSPs must traverse a limited number of optical–electrical–optical (OEO) conversions (equivalently, to traverse limited number of electronic routers and hence reduced electrical processing), besides the bandwidth requirement. This OEO constraint can be specified by users in service level agreement (SLA) or determined by service providers based on the end-to-end delay requirement. We propose two integrated routing algorithms to route traffic with or with no OEO conversion requirements, respectively. These two algorithms can compute primary LSPs and backup LSPs in polynomial time. We consider the case where limited ports are provided at each node in the network and develop two routing approaches called port-independent routing and port-dependent routing. In the port-independent routing, paths are selected first and then port availabilities are checked to setup the path. While this approach is simple to implement, it leads to connection blocking if ports required on the chosen path are not available. In the port-dependent routing, port information is incorporated in the path selection process. It guarantees that a path can be setup once it is found. We evaluate the effectiveness of LSP protection using the proposed algorithms on the NSFNET network.