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VLBI Data Stream Web Demonstration - European Network Topology

Explore a web-based demo sending VLBI data via controlled UDP packets on a high-speed network connecting key European sites. Efficient data handling process explained step by step.

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VLBI Data Stream Web Demonstration - European Network Topology

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

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

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

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

  5. Time The GÉANT Weathermap • Normal Traffic + • Radio Astronomy Data • 500 Mbit/s • Normal Traffic + • Radio Astronomy Data + • Less Than Best Effort • 2.0 Gbit/s • Normal Traffic

  6. Traffic QoS Classes on GÉANT Backbone • Normal Traffic + • Radio Astronomy Data + • Less Than Best Effort • 2.0 Gbit/s • Normal Traffic + • Less Than Best Effort • 2.0 Gbit/s • Normal Traffic + • Radio Astronomy Data • 500 Mbit/s • Normal Traffic

  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

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

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