The EU DataGrid and GÉANT projects demonstrated their collaborative work at the European Research 2002 Exhibition by demonstrating the transfer of Radio Astronomy VLBI data at 500 Mbits/s and the use of different Quality of Service traffic at 2.5Gbit/s as well as job submission to the EU DataGrid. There was a press briefing, a joint press release and flyer for DataGrid.
Information on Radio Astronomy and current VLBI techniques was given in a Web presentation, and a technical presentation gave details of the techniques used in the demonstration and some performace tests made on the networks.
This screen shot of the demonstration shows The Progress Monitor frame which is a set of coloured boxes each representing a 1.8 Gbyte data transfer and the VLBI Transmission Statistics frame that shows the throughput, packet loss and number of out of order packets for each 1.8 Gbyte transmission. In this case there was 1.8Gbit/s of Less than Best Effort traffic (low priority traffic) and this high rate caused the large number of out-of-order packets. But note that the number of lost packets was 0 out of 1.23Million sent, 0-5 lost packets was typical of what was obtained during ER2002. This improvement over the iGrid2002 demonstration was due to use of a separate 1Gbit/s access link from Manchester to SuperJANET4.
The plot above shows the results of a series of tests made at the start of ER2002. Up to 16:00 hours, the green curve shows the normal traffic out of the UK on the GEANT backbone link between the Dante PoPs at London and Amsterdam. The green peak at 17:00 shows the efect of sending the 500 Mbit/s Radio Astronomy VLBI Data. At 18:00 the VLBI Data was turned off and 1.8 Gbit/s of LBE traffic was sent over the London and Amsterdam backbone link as shown by the blue courve; the Normal traffic was unaffected as shown by the green curve that took the toal traffic to 2.0 Gbit/s. At about 19:00 the VLBI Data was turned on. This, the LBE, and the normal traffic exceed the total bandwidth available on the link with the consequence that the LBE traffic is dropped as shown by the dip in the blue curve. The plot below shows the load for the different classes of traffic taken during the demonstration.
Richard Hughes-Jones 20 Nov 02