In this paper, we analyze a performance model for the TCP Congestion Avoidance algorithm. The model predicts the bandwidth of a sustained TCP connection subjected to light to moderate packet losses, such as loss caused by network congestion. It assumes that TCP avoids retransmission timeouts and always has sucient receiver window and sender data. The model predicts the Congestion Avoidance performance of nearly all TCP implementations under restricted conditions and of TCP with Selective A c knowledgements over a much wider range of Internet conditions.We v erify the model through both simulation and live I n ternet measurements. The simulations test several TCP implementations under a range of loss conditions and in environments with both drop-tail and RED queuing. The model is also compared to live I nternet measurements using the TReno diagnostic and real TCP implementations.We also present s e v eral applications of the model to problems of bandwidth allocation in the Internet. We use the model to analyze networks with multiple congested gateways this analysis shows strong agreement with prior work in this area. Finally, w e present several important implications about the behavior of the Internet in the presence of high load from diverse user communities.

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With the growth of high performance networking, a single host may have simultaneous connections that vary in bandwidth by as many as six orders of magnitude. We identify requirements for an automatically-tuning TCP to achieve maximum throughput across all connections simultaneously within the resource limits of the sender. Our auto-tuning TCP implementation makes use of several existing technologies and adds dynamically adjusting socket buffers to achieve maximum transfer rates on each connection without manual configuration.Our implementation involved slight modifications to a BSD-baaed socket, interface and TCP stack. With these modifications, we achieved drastic improvements in performance over large bandwidth*delay paths compared to the default system configuration, and significant reductions in memory usage compared to hand-tuned connections, allowing servers to support at least twice as many simultaneous connections.

This document outlines possible TCP enhancements that may allow TCP to better utilize the available bandwidth provided by networks containing satellite links. The algorithms and mechanisms outlined have not been judged to be mature enough to be recommended by the IETF. The goal of this document is to educate researchers as to the current work and progress being done in TCP research related to satellite networks.