Cross-Layer Speculative-Parallelization Protocol Architecture for End Systems and Gateways in Computer Networks With Lossy Links

— The throughput degradation of Transport Control Protocol (TCP)/Internet Protocol (IP) networks over lossy links due to the coexistence of congestion losses and link corruption losses is very similar to the degradation of processor performance (i.e., cycle per instruction) due to control hazards in computer design. First, two types of loss events in networks with lossy links are analogous to two possibilities of a branching result in computers (taken vs. not taken). Secondly, both problems result in performance degradations in their applications, i.e., penalties (in clock cycles) in a processor, and throughput degradation (in bits per second) in a TCP/IP network. This has motivated us to apply speculative techniques (i.e., speculating on the outcome of branch predictions), used to overcome control dependencies in a processor, to throughput improvements when lossy links are involved in TCP/IP connections. The objective of this paper is to propose a cross-layer system to improve the network throughput over lossy links. This system consists of protocol-level speculation based algorithms at transport layer, and protocol enhancements at middleware and network layers that provide control and performance parameters to transport layer functions. Simulation results show that, compared to prior research, our proposed system is effective in improving network throughput over lossy links, capable of handling incorrect speculations, fair for other competing ows, backward compatible with legacy networks, and relatively easy to implement.