Server based QoS routing with implicit network state updates

We propose centralized server based QoS routing schemes, where a route server is responsible for determining QoS paths on behalf of all the routers in a routing domain. In the proposed server based schemes, the dynamic link QoS state information, which is required for a QoS path computation, is implicitly maintained at the route server as it assigns or gets back QoS paths. By maintaining the network state information this way, we may not only eliminate the overhead to exchange network state update messages but also achieve higher routing performance by utilizing accurate network state information in the path computation. We discuss path caching techniques for reducing the amount of path computation overhead at the route server, and evaluate the performance of the proposed schemes using simulation. The simulation results show that the path caching schemes may significantly reduce the route server load. The proposed schemes are also compared to the distributed QoS routing schemes proposed in the literatures. It has been shown that the proposed server based schemes not only enhance the routing performance, but they are also competitive with respect to routing overheads.