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e-VLBI Trials Ny-Alesund to Haystack (VSI-E non real-time)

e-VLBI Trials Ny-Alesund to Haystack (VSI-E non real-time). C. Ruszczyk, J. Soohoo, A. Whitney [1] , R. Hanssen , F. Koppang [2] , O. Schjelderup, H. Eidnes [3] , S. Bailey, D. Rubincam [4] [1] MIT Haystack [2] NMA, [3] Uninett folks, [4] NASA. Introduction. Purpose:

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e-VLBI Trials Ny-Alesund to Haystack (VSI-E non real-time)

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  1. e-VLBI Trials Ny-Alesund to Haystack (VSI-E non real-time) C. Ruszczyk, J. Soohoo, A. Whitney[1], R. Hanssen , F. Koppang[2], O. Schjelderup, H. Eidnes[3], S. Bailey, D. Rubincam [4] [1] MIT Haystack [2]NMA, [3]Uninett folks, [4]NASA

  2. Introduction • Purpose: • Establishing a direct high-speed data link • NMA Geodetic Observatory in Ny-Ålseund, Svalbard, • to the MIT Haystack Observatory • The long term goal is to be able to deliver observation data in “real time”. • Investigate e-VLBI Transfers • Viability of e-VLBI transfers • Transport protocol research / Analysis tools The NMA Geodetic Observatory in Ny-Ålesund

  3. Introduction (cont) • Trial • January 2006 – Sept 1 2006 • Presently • NMA evaluating results • Determining if e-VLBI is viable • Link exists for protocol testing • December 2006

  4. Constraints • End-System • Black out times existed • Resource scheduling • Deadline Dates • Transfers had to be completed • Microwave Network Links • Rate limited (100Mbps) • Self imposed (shared network) • Fall back position required • Failures on microwave link (20Mbps)

  5. Constraints (cont) • TCP rate limiting • Standard linux traffic shaping • Iproute2 • Tc • Hierarchical token bucket • Classification of traffic • Port, destination IP address • UDP rate limiting • Responsibility of the application

  6. Results • Successful transfers • known file transfer applications (bbftp) • TCP • Performance problems • Errors on the microwave link • Result was reduction in maximum allowable bw • 85Mbps • Averaged about 65Mbps for transfers • Peaks at 85Mbps • Reduced rate resulted -> longer transfers • Network test issues: • Iperf tests • Periodic dropouts (85Mbps) 22 secs – kernel daemon

  7. Results (cont) • VLBI Transport Application (vtp) • UDP • Rate limiting • Older motherboard effected application interaction • Not observed earlier • High end e-VLBI motherboards • Successful transfer of scan • Lower than expected performance • Under evaluation • Side Note • Crashed Haystack network during testing • Not associated with the experiment • E-VLBI test machine sending malformed IP packets

  8. Conclusion • Some success / failures • Interesting issues R&D Transfer • 4.8 TB of data • Length of the scans • Allowed to utilize network for continued research thru the end of the year. • Other transport protocols • Integrated into VSI-E • Vfer, UDT • Comparison

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