Path selection methods for localized quality of service routing

Localized Quality of Service (QoS) routing was recently proposed as an alternative to the QoS routing algorithms that use global network state information to make routing decisions. In localized QoS routing, each router maintains a predetermined set of candidate paths for each of the destinations. For a connection request, a router decides the path for the request based on the information maintained locally at the router. Hence, localized QoS routing does not use any global network state information in the routing process and avoids the problems associated with the maintenance of the global network state information. To achieve good routing performance, localized QoS routing must select the predetermined set of candidate paths between the source and the destination effectively. This paper studies path selection methods for localized QoS routing. Five path selection heuristics, namely breadth-first search path selection, per-pair shortest path selection, global path selection, hybrid per-pair/global path selection, and per-pair path selection with global tuning, are proposed and their performance is evaluated through simulation. We conclude that path selection methods can greatly affect the performance of localized QoS routing and that an effective path selection algorithm must consider various factors, including path length and load balancing in the whole network.