Abstract

International audience; The pre-emption mechanism may be used in Multi Protocol Label Switching Traffic Engineering (MPLS-TE) networks in order to reduce the number of rejected tunnels during failure. But pre-emption may have an impact on the convergence time, and it is required to minimize the number of pre-emptions per tunnel. For that purpose this paper proposes a new pre-emption policy allowing reducing or limiting the number of pre-emptions per tunnel, after a network failure. Two approaches are proposed: A pre-emption reduction approach where the least preempted tunnels are preempted in priority and a pre-emption limitation approach where a tunnel cannot be preempted more than N times during a given period. Simulation results show that we can limit the maximum number of pre-emptions for a given tunnel to only one, without significantly diminishing the rejection reduction capabilities.

Abstract

International audience; 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.