Abstract:

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.

Key words: quality of service routing, constraint, metric, reroute