基于带宽和延时度量的QOSPF改进路由算法

A QOSPF-Improved Routing Algorithm with Bandwidth and Delay Metrics

针对开放最短路径优先(OSPF)服务质量(QoS)扩展(QOSPF)算法中预剪枝高延时链路后仅考虑带宽度量计算路由,提出考虑带宽和延时度量的QOSPF改进(BD-QOSPF)路由算法,为应用流寻找满足其QoS请求(带宽约束、延时最小或延时约束)的可行路径.该算法保持QOSPF的算法复杂度,并支持逐跳和显式路由,比较可用带宽和延时度量预计算路由表,处理等资源、等开销路径和重路由阻塞流.仿真结果表明,BD-QOSPF可提高QoS流路由成功率,降低流路径延时和节省带宽资源;其重路由策略对于改善流阻塞性能是有效的,但要付出随流负荷增长的重路由开销.

Quality of service （QoS） extensions to open shortest path first （QOSPF） algorithm prunes the high-delay network links before routing with only the bandwidth metric. A QOSPF-improved routing algorithm with bandwidth and delay metrics （BD-QOSPF） is proposed to seek feasible paths so as to meet the QoS requests （bandwidth constraint, delay optimization or delay constraint） for application flows. It keeps the same complexity as the original QOSPF and supports hop-by-hop and explicit routing. It compares available bandwidth and delay metrics to pre-compute routing table, deals with the equal-resource and equal-cost paths and reroutes the blocked flows. Simulation results show that BD-QOSPF can increase the routing-success-ratio of QoS flows, and decrease the path delay and save the path bandwidth as well. The effectiveness of rerouting strategy in BD-QOSPF is also verified to improve the flow-block performance, however more rerouting costs directly associated with more flow loads should be paid.