Slow file transfer UK to various European DEISA sites

PTS Case 17

Synopsis

The European Centre for Medium-range Weather Forecasting (ECMWF), which is based in Reading, UK is part of the DEISA project. They contacted the PERT when they noticed slow file transfers to DEISA sites over G�ANT network (typically only 40Mbps) which were very poor compared to an FTP test to a JANET (UK) server (which achieved 300Mbps). The poorest results were between the UK and a site in Barcelona (ES).
The poor TCP transfer rates (10-40Mbps) seen between ECMWF (UK) and the sites in DE, IT, FR and FI, were due to sub-optimal TCP tuning of the ECMWF host. After the PERT-recommended TCP settings were applied transfer rates increased by up to ten times (250-450Mbps). The path to ES was also affected by packet loss on the access circuit between RedIRIS and G�ANT2. Having been identified by the PERT, the degraded circuit was repaired and the packet loss stopped.

– Main.TobyRodwell - 31 Jan 2007