e-VLBI over TransPAC

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e-VLBI over TransPAC
Masaki Hirabaru David Lapsley Yasuhiro Koyama Alan Whitney
Communications Research Laboratory, Japan MIT Haystack Observatory, USA Communications Research Laboratory, Japan MIT Haystack Observatory, USA
masaki_at_crl.go.jp dlapsley_at_haystack.mit.edu koyama_at_crl.go.jp awhitney_at_haystack.mit.edu
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Outline

• Introduction
• Overview of e-VLBI
• Advantages of e-VLBI
• Typical e-VLBI data requirements
• e-VLBI Experiments to date
• Future e-VLBI experiments over TransPAC
• Summary of impact of e-VLBI

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Traditional VLBI
The Very-Long Baseline Interferometry (VLBI)
Technique(with traditional data recording on
magnetic tape or disk)
The Global VLBI Array(up to 20 stations can be
used simultaneously)
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VLBI Science

• ASTRONOMY
• Highest resolution technique available to
  astronomers tens of microarcseconds
• Allows detailed studies of the most distant
  objects

Plate-tectonic motions from VLBI measurements

• GEODESY
• Highest precision (few mm) technique available
  for global tectonic measurements
• Highest spatial and time resolution of Earths
  motion in space for the study of Earths interior
• Earth-rotation measurements important for
  military/civilian navigation
• Fundamental calibration for GPS constellation
  within Celestial Ref Frame

VLBI astronomy example
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e-VLBI

• Traditional VLBI
• Data is recorded onto magnetic media (e.g. tape
  or hard disk) - currently at 1 Gbps/station
• Data shipped to central site
• Data correlated - result published 4d - 15 weeks
  later
• e-VLBI
• Use the network instead of storage media
• Transmit data in real-time or near-real-time from
  instrument (telescope) to processing center
• Many advantages...

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Advantages

• Scientific
• Bandwidth growth potential for higher sensitivity
• Rapid processing turnaround
• Practical
• Real-time diagnostics
• Increased reliability
• Lower cost

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Typical e-VLBI Data Requirements
Description Geodesy Astronomy
Duration(hours) 24/week Blocks of several contiguous days
Telescopes 7 (nominal) Up to 20
Observation Time 30-50 50-75
Data rate(Mbps) 256 1024
Total data collected (/station/day) 1 TB 7 TB
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Typical e-VLBI Data Requirements
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Typical e-VLBI Data Requirements
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e-VLBI Experiments to Date

• Westford-GGAO e-VLBI results
• First near-real-time e-VLBI experiment conducted
  on 6 Oct 02
• GGAO disk-to-disk transfer at average 788 Mbps
  transfer rate
• Several US to Japan demonstrations
• Support of Geodetic e-VLBI experiments
• Up to 100 Mbps sustained for near Real-time
  data transfer
• Sub-24 hour UT1 estimate
• Network performance characterization and protocol
  testing
• 600 Mbps transfer rate in Tokyo to US
  experiment
• Recent 500 TB data transfers of real experimental
  data paving the way for operationalization of
  VLBI transfers
• CRF22, CRF23, T2023, T2024 part of IVS schedule
• Internet2 Demonstration - October 2003
• 644 Mbps using FAST TCP
• 400 Mbps using High Speed TCP (HSTCP)

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High Performance Transfer Protocols

• Tsunami
• Rate-based flow control
• Data over UDP
• Control over TCP
• Mark Meiss, Steve Wallace - Indiana University
• UDT
• Rate-based flow control
• Data and Control over UDP
• Yunhong Gu, Robert Grossman - University of
  Illinois
• FAST TCP
• Windowed, delay-based high performance TCP
• Steven Low, et. al
• Netlab, Caltech

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Tsunami Japan?US(disc-to-disc)
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Tsunami Throughput
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UDT Japan?US
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UDT Throughput
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2004 e-VLBI experimental plan between MIT
Haystack and CRL Kashima at 1Gbps
e-VLBI server
Kashima
test server
100km
1G
Tokyo XP
Koganei
1G
TransPAC
1G x2
9,000km
Chicago
2.5G
MIT Haystack
Abilene

• Continued experiments using commodity Internet
  connectivity at Kashima
• Experiments using 1 Gigabit per second Internet
  connectivity at Kashima
• Experiments using real-time correlation

1G
Los Angeles
New York
4,000km
10G

• Planned 1 Gbps upgrade at Kashima
• Planned 2.5 Gbps upgrade at Haystack

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References

• TSUNAMI
• http//www.indiana.edu/anml/anmlresearch.html
• UDT
• https//sourceforge.net/projects/lambdaftp/
• FAST TCP
• http//netlab.caltech.edu/FAST/index.html

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Summary of Impact of e-VLBI Program

• Opens new doors for national and international
  astronomical and geophysical research.
• Represents an excellent match between modern
  Information Technology and a real science need.
• Motivates the development of a new shared-network
  protocols that will benefit other similar
  applications.
• Drives an innovative IT research application and
  fosters a strong international science
  collaboration.

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Thank you

• David Lapsley
• dlapsley_at_haystack.mit.edu

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