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Recent e-EVN Developments

Explore the milestones and advancements in e-VLBI, including improved connectivity, first results, and the potential for expansion. Learn about the benefits of e-VLBI and its impact on astronomical research.

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Recent e-EVN Developments

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  1. Recente-EVNDevelopments Arpad Szomoru

  2. Outline • The past • Current status • Expansion of e-EVN • EXPReS: first results • Connectivity improvements • The future

  3. Price recording media ($/GB)

  4. January 2002: Proof-of-Concept e-VLBI over GÉANT 0 HU CH IT SE FR DE GR NL CZ BE GEANT AT 2.5 G 1.2 G GÉANT UK PT 622M ES 310 M SI PL IE 155 M 34 M 45 M HR LU EE RO EVN telescope SK LV BG IL CY LT

  5. e-VLBI Milestones • September 2002: • 2 X 1 Gbit Ethernet links to JIVE • Demonstrations at igrid2002 and ER2002 • UDP data rates over 600 Mbit/s

  6. OnsalaSweden Chalmers University of Technology, Gothenburg • November 2003: Cambridge – Westerbork fringes detected, only 15 minutes after observations were made. • 64Mb/s, with disk buffering at JIVE only. • October 2003: first light on Westerbork – JIVE 1 Gb/s connection • May 2003: First use of FTP for VLBI session fringe checks. • September: e-VLBI data transfer between Bologna and JIVE – 300Mb/s • November 2003: OnsalaSpace Observatory (Sweden) connected at 1Gb/s. • July:10 Gbit access GEANT-Surfnet • 6 X 1 Gbit links to JIVE e-VLBI Milestones: 2003

  7. June 2004: network stress test (iperf) involving Bologna, Torun, Onsala and JIVE • April 2004: Three-telescope, real-time fringes at 64Mb/s (On, Jb, Wb). • First real-time EVN image at 32Mb/s • September 2004: First e-EVN science session (Ar, Cm, Tr, On, Wb) • Spectral line observations at 32 Mb/s • December 20 2004:connection of JBO to Manchester at 2 x 1 Gb/s • e-VLBI test with Tr, On and Jb • Jb - Tr fringes at 256Mb/s • January 2004: Disk buffered e-VLBI • On, Wb, Cm at 128Mb/s for first e-VLBI image • On – Wb fringes at 256Mb/s • September 2004: Four telescope real-time e-VLBI (Ar, Cm, Tr, Wb) • First fringes to Ar at 32 Mb/s • March 2004: first real-time fringes Westford-GGAO to Haystack • Intercontinental real-time fringes, Wf -On, 32 Mb/s • June 2004: Torun connected at 1Gb/s. e-VLBI Milestones: 2004

  8. March 2005: e-VLBI science session • First continuum science observations at 128 and 64 Mb/s, involving 6 radio telescopes (Wb, Ar, Jb, Cm, On, Tr) • Spring 2006: Metsahovi connected at 10Gb/s February 2005: network transfer test (BWCTL) employing various network monitoring tools involving Jb, Cm, On, Tr, Bologna and JIVE • January 2005: Huygens descent tracking, salvage of Doppler experiment • Use of dedicated lightpath Australia-JIVE, data transferred at ~450 Mb/s • Summer 2005: trench for “last mile” connection to Medicina dug e-VLBI Milestones: 2005

  9. 1 Gbps 10 Gbps 155 Mbps 2.5 Gbps

  10. Why bother? (change is bad…) • Target of Opportunity - unscheduled observations triggered by sudden astronomical events. This capability will become much more important when LOFAR comes online • Adaptive Observing - Use e-VLBI as a finder experiment • Or, e-VLBI sessions a few days apart, adapt schedules for later observations based on results (rapid results on large sample, focus in detail on best candidates) • Automatic Observing - small number of telescopes observing for extended periods doing spectral line observations of large galactic samples • Interface with other real-time arrays – e-MERLIN, LOFAR, SKA.. Also function as SKA-pathfinder • Bandwidth no longer limited by magnetic media: 10Gbps technology already becoming mainstream • Because we can…

  11. Recent developments • Regular science/test sessions throughout the year • First open calls for e-VLBI science proposals • First science run completely lost, but, first ever real-time fringes to Mc (128 Mbps) • Second and third science runs: many hours of smooth sailing at 128 Mbps. No excitement, no drama. JIVE becoming an observatory?

  12. First e-EVN Astronomy Publications

  13. Current status • Technicaltests: • 6-station fringes at 256 Mbps • first European 512 Mbps fringes (Jb and Wb, May 18) • 3-station 512 Mbps fringes (Cm, Wb, On, August 21) • first fringes using new 5 GHz receiver at Mc • Current connectivity: • Ar: 64 Mbps in the past, but <32 Mbps this year • European telescopes: 128 Mbps always, 256 Mbps often, 512 Mbps to Wb, Jb and On

  14. Tr connectivity bottleneck – (partially) solved • Black Diamond 6808 switches: • New interfaces (10GE) system in old architecture (1GE) • Originally 8x1GE interface per card • 10GE NIC served by 8 x 1GE queues • Queuing regime – RR (packet based) and flow-based • Flow based: • Max. flow capacity – 1Gbit/s – backround traffic. • There is no known reordering workaround to solve this problem.

  15. e-VLBI to South America? SMART-1 SMART-1 factsheet Testing solar-electric propulsion and other deep-space technologiesName SMART stands for Small Missions for Advanced Research in Technology.  Description SMART-1 is the first of ESA’s Small Missions for Advanced Research in Technology. It travelled to the Moon using solar-electric propulsion and carrying a battery of miniaturised instruments. As well as testing new technology, SMART-1 is making the first comprehensive inventory of key chemical elements in the lunar surface. It is also investigating the theory that the Moon was formed following the violent collision of a smaller planet with Earth, four and a half thousand million years ago.Launched 27 September 2003 Status Arrived in lunar orbit, 15 November 2004. Conducting lunar orbit science operations. Notes SMART-1 is the first European spacecraft to travel to and orbit around the Moon. This is only the second time that ion propulsion has been used as a mission's primary propulsion system (the first was NASA's Deep Space 1 probe launched in October 1998). SMART-1 is looking for water (in the form of ice) on the Moon. To save precious xenon fuel, SMART-1 uses 'celestial mechanics', that is, techniques such as making use of 'lunar resonances' and fly-bys.

  16. e-VLBI to Sourth America (2)

  17. And other continents.. Australia: • Telescopes connected • PCEVN-Mk5 interface needed China: • Shanghai Observatory connected at 2.5Gbps • Connection via TEIN (622Mbps), ORIENT? Issues with CERNET, CSTNet • Direct lightpath Hong Kong-Netherlight?

  18. Hybrid networks in the Netherlands..

  19. Switch from Cisco to Nortel/Avici equipment has been completed: for now, 7 * 1 Gbps, ultimately 16 * 1 Gbps lightpaths + 10 Gbps IP connection

  20. ..and across Europe: GÉANT2 network upgrade Outline

  21. EXPReS: getting underway SA1: new hires at JIVE; two software engineers, one network engineer (finally!), one e-VLBI postdoc Inclusion of e-MERLIN telescopes in e-EVN Operational improvements (deliverable driven): • Robustness • Reliability • Speed • Ease of operation • Station feedback And still, pushing data rates, protocols, UDP, Circuit TCP? Get rid of fairness… Better usage of available bandwidth.

  22. e-VLBI control interface

  23. Interface to station Mk5s

  24. Runtime control

  25. Integrating fringe display

  26. Data status monitor

  27. Streamlining of post processing

  28. Web-based Post-processing

  29. Ongoing New control computers (Solaris AMD servers) • Cut down on (re-)start time • Powerful code development platform • Tightening up of existing code • Operational within next few weeks Other hardware upgrades: • SX optics (fibres + NICs), managed switches at JIVE and SARA • Mark5A→B: motherboards, memory, power supplies, serial links, CIBs

  30. And coming.. FABRIC: (Huib Jan van Langevelde) • Distributed software correlation • High bandwidth data transport (On part of e-MERLIN @ 4Gbps) • Two new hires at JIVE SCARIe: • Collaboration with SARA and UvA • Distributed software correlation using Dutch grid • Lambda switching, dynamical allocation of lightpaths, collaboration with DRAGON project • JIVE postdoc hired, still looking for UvA postdoc

  31. Connectivity improvements Martin Swany

  32. 2 Heavy duty gamer PCs • Tyan Thunder K8WE Motherboards • Dual AMD Opteron 2.4GHz processors • 4GB RAM • 2 1Gb PCI-Expres Nics • First one at Torun, back-to-back to Mark5 • Second one located at Poznan Supercomputing Centre

  33. Protocol work in Manchester: • Protocol Investigation for eVLBI Data Transfer • Protocols considered for investigation include: • TCP/IP • UDP/IP • DCCP/IP • VSI-E RTP/UDP/IP • Remote Direct Memory Access • TCP Offload Engines • Work in progress – Links to ESLEA UK e-science • Vlbi-udp – UDP/IP stability & the effect of packet loss on correlations • Tcpdelay – TCP/IP and CBR data

  34. Protocols (1) Mix of High Speed and Westwood TCP (Sansa)

  35. Protocols (2) Circuit TCP (Mudambi, Zheng and Veeraraghavan) Meant for Dedicated End-to-End Circuits, fixed congestion window No slow start, no backoff: finally, a TCP rude enough for e-VLBI?

  36. Protocols (3) Home-grown version of CTCP using pluggable TCP congestion avoidance algorithms in newer Linux kernels (Mark Kettenis) Rock-steady 780 Mbps transfer using iperf from Mc to JIVE Serious problem with new version of Mk5A software under newer kernels

  37. Aim: 16 * 1 Gbps production e-EVN network Lightpaths across GÉANT: point-to-point connections between JIVE and telescopes. Guaranteed bandwidth, no need to worry about congestion.. Depending on connectivity of stations, choice of configurations with specific data rates Towards a true connected-element interferometer; we’re well on our way e-EVN: the future

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