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 GÉANT 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 GÉANT2. Having been identified by the PERT, the degraded circuit was repaired and the packet loss stopped.

-- TobyRodwell - 31 Jan 2007

Topic revision: r1 - 2007-01-31 - TobyRodwell
 
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