Residual bandwidth as localized QoS routing metric

Quality of service (QoS) routing has been proposed for supporting the requirements of network applications and satisfying connection constraints. A large amount of information needs to be exchanged periodically among routers. Therefore, in order to satisfy such requirements localized QoS routing algorithms have been proposed. This is where source nodes make routing decisions based on statistics collected locally. Using local information for routing avoids the overheads of exchanging global information with other nodes. In this paper we present a localized bandwidth-based QoS routing (BBR) algorithm, which relies on residual bandwidth that each path can support to make routing decisions. We compare our scheme with Credit Based Routing (CBR) and the commonly used global WSP routing scheme under different traffic loads and network topologies. We demonstrated through simulation that our scheme performs better than CBR and outperforms the WSP scheme in some network topologies, even for a small update interval of link state.