DataGrid-GÉANT tests prove GÉANT’s ability to support Grids
December 2003
Tests performed by researchers* participating in the European DataGrid (EDG) project in collaboration with engineers from DANTE, which operates GÉANT, have successfully demonstrated the ability of GÉANT to sustain high data throughput for TCP traffic even under congested conditions. The network’s ability to support high UDP traffic rates has been proven previously**, but the EDG tests, using TCP traffic, are important due to TCP’s sensitivity to network congestion. TCP helps multiple users to share capacity on a given link, however, which supports the working model envisaged by Grid projects and thus makes TCP the preferred transmission protocol.
The tests were performed by transferring TCP traffic between two ordinary DataGrid PCs sited in the UK and the Netherlands respectively. The bandwidths achieved – up to 920 Mbps - rank amongst the highest ever measured for PCs communicating using TCP over long distances. The rate is more than 16,000 times faster than a typical computer modem. It would allow you to download a full CD in six seconds, or a feature-length DVD and all its extras in about 40 seconds.
These speeds were achieved with normal PCs, not high-end servers or workstations.
The PCs were directly connected to GÉANT routers in London and Amsterdam by gigabit Ethernet. Smartbits, kindly loaned by Spirent plc, were installed at the GÉANT PoPs in London and Frankfurt in order to generate congestion on a part of the network path (FR-BE-NL). The Smartbits were connected with the help of gigabit ethernet networkcards loaned by Juniper. This allowed the data transfer experiments to be conducted under non-ideal network conditions (a bit like measuring the length of a bus journey during rush hour instead of on a Sunday morning).
The experiment was performed by routing the traffic between the two PCs along a short path (UK-FR-BE-NL) and a long path (UK-SE-DE-IT-CH-FR-BE-NL). Despite the Smartbits-generated congestion, GÉANT was able to achieve speeds of 920 Mbps along the short path, and 840 Mbps along the long path.
The tests prove that thanks to GÉANT, computers and other equipment used in research, located thousands of kilometres apart, can communicate with the same convenience as if they sat side by side in the same room. GÉANT and Grids together open up exciting new collaboration opportunities for researchers in fields as diverse as astronomy, climate modelling or proteomics.”
* The tests were performed in cooperation with Franck Bonnassieux and Richard Hughes-Jones, from the EDG Work Package 7 team.
** See http://archive.dante.net/geant/geant-publicity.html#SHDTdemo for further information.
