A comparative study of QoS routing schemes that tolerate imprecise state information

In large networks, maintaining precise global network state information is almost impossible. Many factors, including non-negligible propagation delay, infrequent link state update due to overhead concerns, link state update policy, resource reservation, and hierarchical topology aggregation, have impacts on the precision of the global network state information. To achieve efficient quality of service (QoS) routing, a practical routing algorithm must be able to make effective routing decisions in the presence of imprecise global network state information. In this paper, we compare five QoS routing algorithms that were proposed to tolerate imprecise global network state information, safety-based routing, randomized routing, multi-path routing, localized routing, and static multi-path routing. The performance of these routing algorithms are evaluated under two link state update policies, the timer based policy and the threshold based policy. The strengths and limitations of each scheme are identified.