Performance modeling of HS-RR-TCP over load-balanced optical burst-switched (OBS) networks

TCP-over-OBS is a promising transport paradigm to support next-generation Internet. It is well known that load-balanced routing generally improves loss performance over OBS. We identify that implementing TCP over load-balanced OBS could lead to persistent out-of-order delivery of TCP segments, resulting in unnecessary timeouts and fast retransmissions. In this paper we evaluate the performance of Reordering-Robust TCP (RR-TCP) over OBS networks. We develop an analytical end-to-end transfer delay model for TCP SACK and RR-TCP over load-balanced OBS networks. We observe that standard TCP experiences significant throughput degradation due to persistent packet reordering. Through simulations and modeling we show that RR-TCP achieves significant improvement compared to TCP SACK. In our simulations we add High-Speed TCP functionality to RR-TCP (HS-RR-TCP). The simulations show up to a 300% performance improvement for HS-RR-TCP compared to HS-TCP-SACK under ideal conditions and a 20% improvement on NSFnet with background traffic.