DS-TE网络环境中的抢占算法

Preemption Algorithm for DS-TE Networks

针对V-PREPT(Versatile Preemption)算法因只关心最小化抢占总代价,不考虑被抢占标记交换路径的规模而引起重路由开销极大增加的问题,提出了改进算法——N-PREPT。该算法在最小化抢占总代价的前提下,根据参数设置的不同分别对标记交换路径进行抢占。将最小化抢占路径数目、避免发生级联抢占的优化标准置于首位,通过采用层层逼近规则提高对抢占数目的约束程度。实验结果表明,当网络中发生抢占时,改进算法在减少重路由开销方面的性能优于V-PREPT算法,提高了网络资源的利用率和网络的QoS(Quality of Service)保障能力。

The V-PREFF （Versatile Preemption） algorithm only concerns with minimizing the total cost of preemption leaving out the number of LSPs （Label Switching Paths） to be preempted, leading to excessive number of rerouting decisions. In this paper, an algorithm providing utilization rate of network resources and QoS （Quality of Service） , named N-PREPT is proposed. The N-PREPT algorithm executes the preemption of LSPs according to the main preemption optimization criteria, under the premise of minimizing the total cost of preemption. It considers minimizing number of LSPs to be preempted and avoiding the occurrence of cascading preemption at first and uses hierarchical approximation method to raise restriction to the number of preemption. Simulation results show that the proposed algorithm significantly outperforms the V-PREPT algorithm when preemption occurs in the network.