An explicit router feedback framework for high bandwidth-delay product networks

Links with high bandwidth ranging from 1 to 10 Gbps are increasingly in use worldwide. Congestion control with the positive use of router feedback that explicitly indicates network conditions is a promising way to address the performance issues of congestion control especially in such high-speed networks. In this paper, we propose SIRENS, a scalable, robust, and flexible fine-grained explicit router feedback framework. SIRENS is a per-hop and in-band notification scheme where each router captures a snapshot of the various kinds of downstream link status along the IP-level path from a sender to a receiver and notifies the receiver of the status. The receiver can find out the overall path status by assembling all the cumulative notifications that indicate the status in each of the single hops and by feedback can share this information with the sender. Such per-hop information is needed by end-hosts if we are to flexibly design novel congestion control mechanisms or to significantly improve the performance of conventional forms of congestion control. We show the feasibility of SIRENS in terms of router processing overhead through the development and evaluation of a network-processor-based high-performance network emulator. As a typical application of SIRENS, we show the configuration of TCP Limited Slow-Start. Through the implementation and evaluation, we have made sure that a sender can shift from the slow-start phase to the congestion avoidance phase without any packet drop, and can achieve more effective bandwidth utilization.