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32 bit words bits vertical. Timestamp. Data. Bit Stream. ~ 7.1 UDP Packets / Data Track Frame. Data Track Frame. iGRID2002 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.

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Igrid2002 radio astronomy vlbi demo

32 bit words bits vertical

Timestamp

Data

Bit Stream

~ 7.1 UDP Packets / Data Track Frame

Data Track Frame

iGRID2002 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


European Topology: NRNs, Geant, Sites

SURFnet

Manchester

Jodrell

iGrid 2002

JIVE

SuperJANET4

CERN


The works

TCP Control

Raid0

Disc

Raid0

Disc

RingBuffer

RingBuffer

UDP Data

Web Interface

n bytes



time

Wait time

The Works:


Receiving packets

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


Udp throughput on the production wan

50 bytes

UDP Man-UvA Gig 19 May 02

100 bytes

1000

200 bytes

400 bytes

900

600 bytes

800 bytes

800

1000 bytes

Recv Wire rate Mbits/s

700

1200 bytes

1472 bytes

600

500

400

300

200

100

0

0

5

10

15

20

25

30

35

40

Transmit Time per frame us

UDP Throughput on the Production WAN

  • Manc-UvA SARA 750 Mbit/s

  • SJANET4 + Geant + SURFnet

  • 75% Manchester Access link

  • Manc-UvA SARA 825 Mbit/s


Acknowledgements
Acknowledgements

  • Boston Ltd supply of the SuperMicro servers & donation of SCSI disks and backplane

    • Dev , Alex Tyagi , Gili-Ross

  • Brunell University

    • Peter van Santen

  • JIVE

    • Steve Parsley, Sergei Pogrebenko

  • Metsähovi Radio Observatory

    • Ari Mujunen

  • SURFnet & Universiteit van Amsterdam

    • Pieter de Boer, Erik.Radius, Cees de Laat, 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)


Gigabit tcp throughput on the production wan
Gigabit TCP Throughput on the Production WAN

  • Throughput vs TCP buffer size

  • TCP window sizes in Mbytes calculated from RTT*bandwidth


UDP Throughput: SLAC - Man

  • SLAC – Manc 470 Mbit/s

  • 75% of the 622 Mbit access link

  • SuperJANET4 peers with ESnet at 622Mbit in NY


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