e-vlbi over transpac masaki hirabarudavid lapsleyyasuhiro koyamaalan whitney communications research...
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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
[email protected] [email protected] [email protected] [email protected]
• 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
Outline
Traditional VLBIThe 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)
Chautauqua 2001
Quasars, hotspots, polarization
VLBI astronomy example
ASTRONOMY• Highest resolution technique available to
astronomers – tens of microarcseconds• Allows detailed studies of the most distant
objects
GEODESY• Highest precision (few mm) technique
available for global tectonic measurements• Highest spatial and time resolution of
Earth’s motion in space for the study of Earth’s interior
•Earth-rotation measurements important for military/civilian navigation•Fundamental calibration for GPS constellation within Celestial Ref Frame
VLBI Science
Plate-tectonic motions from VLBI measurements
• 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...
e-VLBI
Advantages
• Scientific:– Bandwidth growth potential for higher sensitivity
– Rapid processing turnaround
• Practical– Real-time diagnostics
– Increased reliability
– Lower cost
Typical e-VLBI Data Requirements
Description Geodesy Astronomy
Duration(hours) 24/weekBlocks 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
Typical e-VLBI Data Requirements
e-VLBI Data Requirements(per-Telescope)
0
50
100
150
200
1 10 100 1000 10000
Average Transfer Rate (Mbps)
Total Transfer Time (h)
Intensive Geodesy Astronomy (1 day)
IntensiveCRL/Haystack
June 2003
T2023CRL/Haystack/MPI
November 2003
Wetzell, Germany Haystack, USAKashima, Japan (2004)NASA GGAO, USA
Onsala, SwedenWestford, USA
Westerbork, The Netherlands
Kashima, Japan (2003)
Haystack, USA(2004)
Physical shipping of media
CRF22/23CRL/Haystack/USNO
October/November 2003
TestGGAO/Westford
October 2002
Arecibo, USAKokee Park, USA
Typical e-VLBI Data Requirements
e-VLBI Data Requirements(Correlator)
0
50
100
150
200
1 10 100 1000 10000
Average Transfer Rate (Mbps)
Total Transfer Time (h)
Intensive Geodesy Astronomy (1 day)
Physical shipping of media
Wetzell, Germany Haystack, USAKashima, Japan (2004)NASA GGAO, USA
Onsala, SwedenWestford, USA
Westerbork, The Netherlands
Kashima, Japan (2003)
Haystack, USA(2004)
Arecibo, USAKokee Park, USA
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)
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
Tsunami: JapanUS(disc-to-disc)
Tsunami: ThroughputTSUNAMI Throughput v. Target rate: Japan to USA
0
100
200
300
400
500
600
700
800
900
1000
0 200 400 600 800 1000 1200
Target Rate (Mbps)
Throughput (Mbps)
Perf5->Turtle(disc2disc) Perf5->Enterprise(disc2disc) Perf5->Enterprise (mem2mem)Turtle (write) Enterprise (write) Perf5 (read)
UDT: JapanUS
UDT ThroughputUDT Throughput: Japan to USA
0
100
200
300
400
500
600
700
1 2 3 4 5
Trial Number
Bandwidth (Mbps)
Perf5->Enterprise(mem2mem) Perf5->Enterprise(disc2disc)
Average=545 Mbps
Average=356 Mbps
Tokyo XP
Kashima
1G
2.5G
TransPAC
9,000km
4,000kmLos Angeles
Chicago
New York
MIT Haystack
10G
1GAbilene
1G
100km
e-VLBI servertest server
1G x2
Koganei
2004 e-VLBI experimental plan between MIT Haystack and CRL Kashima at
1Gbps
– Continued experiments using commodity Internet connectivity at Kashima
– Experiments using 1 Gigabit per second Internet connectivity at Kashima
– Experiments using real-time correlation
– Planned 1 Gbps upgrade at Kashima
– Planned 2.5 Gbps upgrade at Haystack
References
• TSUNAMI– http://www.indiana.edu/~anml/anmlresearch.html
• UDT– https://sourceforge.net/projects/lambdaftp/
• FAST TCP– http://netlab.caltech.edu/FAST/index.html
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.
http://www.haystack.mit.edu
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