Impact of QoS differentiation on congestion Window dynamics and throughput of High Speed TCP protocols on LOBS testbed

In this paper, performance of different high performance Transmission Control Protocol (TCP) flavors in vogue like high speed TCP, HTCP, scalable TCP, TCP BIC, TCP CUBIC, TCP Hybla, TCP Reno, TCP Vegas, TCP Veno and TCP Westwood in terms of congestion window fluctuations (cwnd), throughput and delay on real time labeled optical burst switching (LOBS) network testbed has been evaluated. It has been experimentally proved that different TCP flavors have different operating range of offset time (which is direct measure of QoS on OBS network) which shows that there are bindings on selection of relative as well as absolute QoS on OBS network. Finally, a cross layer design approach for TCP over OBS has been necessitated in which TCP layer should estimate RTT in terms of OBS parameters especially offset time which have direct impact on RTT and hence TCP cwnd dynamics.