Early drop scheme for providing absolute QoS differentiation in optical burst-switched networks

There have been several schemes proposed to provide relative differentiated service in OBS. One such scheme is the proportional QoS scheme. However, to meet the requirements of a wide variety of applications, the backbone OBS network must provide absolute QoS differentiation. There is no work in the literature to provide support for this crucial QoS model. We propose an absolute QoS model in the backbone network with admission control and resource provisioning at the edge nodes and with loss guarantee at each core node. We also propose two approaches to guarantee worst-case loss probability at the core nodes: early drop by threshold (EDT) and early drop by span (EDS). We compare the performance of these proposed approaches with the proportional QoS scheme. Simulation results showed that the EDS outperforms EDT and the proportional QoS scheme in providing loss guarantee and also reduces the loss of other non-guaranteed traffic.