The preemption policy currently in use in MPLS-enabled commercial routers selects LSPs for preemption based only on their priority and holding time. This can lead to waste of resources and excessive number of rerouting decisions. In this paper, a new preemption policy is proposed and complemented with an adaptive scheme that aims to minimize rerouting. The new policy combines the three main preemption optimization criteria: number of LSPs to be preempted, priority of the LSPs, and preempted bandwidth. Weights can be configured to stress the desired criteria. The new policy is complemented by an adaptive scheme that selects lower priority LSPs that can afford to have their rate reduced. The selected LSPs will fairly reduce their rate in order to accommodate the new high-priority LSP setup request. Performance comparisons of a nonpreemptive approach, a policy currently in use by commercial routers, and our policies are also investigated.

The explosive growth of the Internet has induced a need for developing tools to understand the composition and dynamics of the Internet traffic. Measurements of the various characteristics of a network provide insight into the state and performance of the network whether it is behaving as expected and whether changes in the network have improved or degraded its performance. Available bandwidth on the links of a network is an important metric which can predict the performance of the network. In this paper, an estimation algorithm for the available bandwidth on a link is presented. The algorithm estimates the available bandwidth and tells the duration for which the estimate is valid with a high degree of confidence. The algorithm dynamically changes the number of past samples that an used for prediction and also the duration for which the prediction holds.

In this paper, a new preemption policy is proposed and complemented with an adaptive scheme that aims to minimize rerouting. The preemption policy combines the three main optimization criteria: number of LSP to be preempted, priority of LSP to be preempted, and amount of bandwidth to be preempted. The preemption policy is complemented by an adaptive scheme that selects LSP with lower priority and reduces their rate in order to accommodate the new high-priority LSP setup request. Heuristics for both preemption and adaptive preemption policies are derived. Simulation results show the heuristics' accuracy. Performance comparisons of a non-preemptive approach, our preemption policy, the adaptive rate policy, and the policy in use by commercial routers are included.