Conference Proceeding

TCP Smart Framing: A Segmentation Algorithm to Improve TCP Performance.

01/2003; DOI:10.1007/3-540-36480-3_20 In proceeding of: Quality of Service in Multiservice IP Networks, Second International Workshop, QoS-IP 2003, Milano, Italy, February 24-26, 2003, Proceedings
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ABSTRACT In this paper we propose an enhancement to the TCP protocol, called TCP Smart Framing , or TCP-SF for short, that enables the Fast Retransmit/Recovery algorithm even when the congestion window is small. TCP-SF is particularly ef- fective for short-lived flows, as most of the current Interne t traffic is. Without modifying the TCP congestion control based on the additive-increase/multiplicative- decrease paradigm, TCP-SF adopts a novel segmentation algorithm: while Clas- sic TCP starts sending one segment, a TCP-SF source is allowed to send an initial window of 4 smaller segments, whose aggregate payload is equal to the connec- tion's . This key idea can be implemented on top of any TCP flavor, from Tahoe to SACK, and requires modifications to the server behav ior only. Analytical results, simulation results, as well as testbed implementation measure- ments show that TCP-SF sources manage to outperform Classic TCP in terms of completion time.

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    ABSTRACT: Wireless and satellite networks often have non-negligible packet corruption rates that can significantly degrade TCP performance. This is due to TCP’s assumption that every packet loss is an indication of network congestion (causing TCP to reduce the transmission rate). This problem has received much attention in the literature. In this paper, we take a broad look at the problem of enhancing TCP performance under corruption losses, and include a discussion of the key issues. The main contributions of this paper are: (i) a confirmation of previous studies that show the reduction of TCP performance in the face of corruption loss, and in addition a plausible upper bound achievable with perfect knowledge of the cause of loss, (ii) a classification of the potential mitigation space, and (iii) the introduction of a promising new mitigation that employs rich cumulative information from intermediate nodes in a path to form a better congestion response.We first illustrate the performance implications of corruption-based loss for a variety of networks via simulation. In addition, we show a rough upper bound on the performance gains a TCP could get if it could perfectly determine the cause of each segment loss––independent of any specific mechanism for TCP to learn the root cause of packet loss. Next, we provide a taxonomy of potential practical classes of mitigations that TCP end-points and intermediate network elements can cooperatively use to decrease the performance impact of corruption-based loss. Finally, we briefly consider a potential mitigation, called cumulative explicit transport error notification (CETEN), which covers a portion of the solution space previously unexplored. CETEN is shown to be a promising mitigation strategy, but a strategy with numerous formidable practical hurdles still to overcome.
    Computer Networks. 01/2004;

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M. Mellia