Using network flows in hierarchical QoS routing

Quality of Service (QoS) routing is the process of routing a connection through a network based on its resource requirements. In QoS routing a lot of overhead is generated either due to the state maintenance or during the call establishment. These overheads increase with the network size. Hence to deploy QoS routing in very big networks, special techniques for reducing these overheads have to be developed. State aggregation is an important technique for reducing the state maintenance overhead. In state aggregation, each domain constructs an aggregated topology of itself, and sends it to other domains. Other domains make routing decisions based on this aggregated information. However, as the network resources change dynamically, the information sent by a domain quickly becomes out-of-date. This stale information leads to bad routing decisions and hence the routing performance goes down. If a domain can update the aggregated information sent by other domains, better routing decisions can be made and hence the routing performance can improve. In this paper, based on "network flows", we propose a new scheme for aggregating bandwidth. Our scheme enables a domain to update the aggregate sent by another domain and thus keep track of resources available in other domains. We also give a distributed approach for inter-domain routing based on our proposed aggregation scheme. Simulation results show that our method gives a better bandwidth admission ratio when compared to existing aggregation techniques.