Minimizing re-routing in MPLS networks with preemption-aware constraint-based routing

In this paper, we study the effect of distributed constrained shortest path first (CSPF)-based path selection on the dynamics of label switched path (LSP) preemption. We propose new CSPF algorithms for minimizing preemption of lower priority LSPs without requiring any enhancements to the recently proposed link-state parameters. The difference between priority-based path selection methods and previously proposed CSPF methods lies in the way the selection is done among equal cost shortest paths. Our priority-aware CSPF algorithms decrease the number of preempted lower priority LSPs while the LSP setup success ratio is basically the same for all methods. (C) 2002 Elsevier Science B.V. All rights reserved.