Advanced satellite infrastructures in future global Grid computing: network solutions to compensate delivery delay

Scientific equipments in remote locations are often integrated in a Grid network by means of satellite links. When the Grid is an Internet overlay network, TCP-like congestion control protocols tend to introduce large delays and to achieve poor bandwidth utilization during the startup phase due to the large bandwidth-delay product of the satellite link. Recent studies demonstrate that the loss of performance is high when a demand assignment multiple access (DAMA) scheme is adopted to manage satellite resources. To overcome this problem, we propose a new mechanism based on Quick Start, a recent IETF recommendation, to enhance the startup performance of data and streaming flows. We show, by means of extensive simulations, that our modifications to enable a QS based DAMA algorithm allow the initial end- to-end delay to be significantly reduced and the queue length in transmitting nodes stabilized. Moreover, our results point out that the startup delay is quite independent of the flow rate, which makes this algorithm suitable to the high bitrate required by Grid computing applications.