A study on Probe Based Admission Control for Multicast and further enhancement

Real-time applications such as multimedia streaming and video conferencing have quite stringent Quality of Service (QoS) requirements from the network, because they are more sensitive to available bandwidth and loss rate than non real-time traffic. To provide scalable and simple Quality of Service (QoS) mechanism for multicast services, Probe-Based Multicast Admission Control (PBMAC) scheme was proposed. In this paper, PBMAC is studied and so-called subsequent request problem found in PBMAC, which degrades system performance significantly when the network traffic is heavily loaded, is further investigated. Based on the analysis on subsequent request problem, a variant of Enhanced PBMAC (VEPBMAC) scheme is proposed, in which when a subsequent request arrives, the request is accepted without probing the link further instead of complementary probing devised in Enhanced PBMAC (EPBMAC) to solve this problem. This leads to further reduction in the bandwidth requirement for probe flows. Simulation results on the study conducted on PBMAC are presented.