TCP Hybla Performance in GEO Satellite Networks: Simulations and Testbed

TCP connections that incorporate satellite links are greatly disadvantaged with respect to entirely wired connections, because of their longer round trip times (RTTs). TCP Hybla has been conceived with the primary aim to solve this problem, therefore it appears quite promising in geostationary (GEO) satellite environments, where the long propagation time greatly affects the RTT. In order to compare TCP Hybla with TCP NewReno, SACK and Westwood in the satellite environment, we have reproduced suitable scenarios based on a GEO bent-pipe satellite by means of both the ns2 simulator and a Linux-based testbed developed at University of Bologna. The obtained results show that TCP Hybla allows a better efficiency in utilizing the available satellite bandwidth, especially for high packet error rates and/or high satellite bandwidth values. This work has been carried out within the European-funded network of excellence SatNEx II (contract No. IST-027393)