Improved MPLS-TE LSP Path Computation using Preemption

In multi-protocol label switching-traffic engineering (MPLS-TE) networks with distributed tunnel path computation on head-end routers, tunnel requests are handled one by one, in an uncoordinated manner without any knowledge of future and other requests. The order in which requests are handled has a significant impact on the network optimization and blocking probability. If it is not possible to control the arrival order, in return it is possible, in some cases, to reorder requests using the preemption function. This paper evaluates the impact of the arrival order, so as to determine efficient orders. It then proposes two preemption strategies so as to reorder arrivals and evaluate these strategies applied to the shortest constrained path computation algorithm.