1. ER2002 Radio Astronomy VLBI Demo. uWeb based demonstration sending VLBI data A controlled stream of UDP packets 256-500 Mbit/s on the production network Man  Amsterdam 32 bit words bits vertical Bit Stream ~ 7.1 UDP Packets / Data Track Frame Timestamp Data Data Track Frame

2. European Topology: NRNs, Geant, Sites SuperJANET4 Brussels ER 2002 Manchester Jodrell SURFnet Amsterdam

3. The Works: n bytes Wait time time  Raid0 Disc UDP Data Raid0 Disc RingBuffer TCP Control Web Interface

4. Receiving Packets Time 1234612346 Incoming packet ids 1 2 3 4 Move 6 Continue with 7 uPackets have Header with packet id + Data Put header directly into control area Put data directly into ring buffer No extra copy uAssume UDP packet arrive in order none lost Deposit data into next consecutive slot uInspect Header Move data onward to correct location Record: The received inter-packet spacing 1-way delay

5. The GÉANT Weathermap uNormal Traffic uNormal Traffic + uRadio Astronomy Data 500 Mbit/s uNormal Traffic + uRadio Astronomy Data + uLess Than Best Effort 2.0 Gbit/s Time

6. Traffic QoS Classes on GÉANT Backbone uNormal Traffic uNormal Traffic + uLess Than Best Effort 2.0 Gbit/s uNormal Traffic + uRadio Astronomy Data 500 Mbit/s uNormal Traffic + uRadio Astronomy Data + uLess Than Best Effort 2.0 Gbit/s

7. UDP Throughput on the Production WAN Manc-UvA SARA 700 Mbit/s SJANET4 + Geant + SURFnet 70% Manchester Access link

8. Gigabit TCP Throughput on the Production WAN Throughput vs TCP buffer size TCP window sizes in Mbytes calculated from RTT*bandwidth LinkRound trip time ms TCP Window for BW 1 Gbit/s TCP Window for UDP BW 750 Mbit/s TCP Window for UDP BW 460 Mbit/s Man – Ams14.51.81.36 Man - CERN21.42.681.23

9. Acknowledgements uBoston Ltd supply of the SuperMicro servers & donation of SCSI disks Dev Taygi, Alex Gili-Ross uBrunell University Peter van Santen uDante Marian Garcia, Nicolas Simar, Dale Robertson, Roberto Sabatino, uJIVE Steve Parsley, Sergei Pogrebenko uMetsähovi Radio Observatory Ari Mujunen uSURFnet & Universiteit van Amsterdam Pieter de Boer, Erik.Radius, Cees de Laat, Antony Antony, Mieke van de Berg uUKERNA Robin Arrack, Bob Day, Jeremy Sharp uUniversity of Manchester Richard Hughes-Jones, Ralph Spencer, Paul Burgess, Robin Hughes-Jones Design of web interface (Undergraduate, Oxford University)