This paper investigates the performance of various versions of the hyper text transfer protocol (HTTP) over a geosynchronous satellite link. Both HTTP/1.0, the currently popular form of the protocol, and HTTP/1.1, the recently standardized form of HTTP, are studied. Next, we quantify the impact of a moderate bit-error rate on the performance of HTTP. Finally, we expand the mathematical model of HTTP presented in Heidemann, Obraczka and Touch (IEEE/ACM ¹ransactions on Networking 1997; 5:616}630) to encompasses a wider range of HTTP behaviour. We show this model accurately predicts HTTP throughput by comparing it with HTTP transfers made over a satellite channel.

This paper describes testing performed to validate operation of Space Communications Protocol Suite Transport Protocol (SCPS-TP) relative to the specification and perform a comprehensive comparison of SCPS-TP protocol options to IP based protocols.Tests were performed at Glenn Research Center to validate the operation of SCPS-TP relative to the Consultative Committee on Space Data Systems (CCSDS) specification, to perform a comprehensive comparison of SCPS-TP protocol options to IP based protocols, and to determine the implementation maturity level of these protocols -particularly for higher speeds. The testing was performed over reasonably high data rates of up to 100 Mbps with delays that are indicative of near planetary environments. The tests were run for a fixed packet size, but for various errored environments. The results indicated that SCPS-TP congestion-friendly options perform slightly better than TCP SACK protocols at moderate and high error-rates. The results also show that existing standard transport protocols and capabilities (drawn from a variety of communities) appear to satisfy all known mission needs.

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.

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