e-VLBI at ≥ 1 Gbps -- “unlimited” networks? Tasso Tzioumis Australia Telescope National Facility (ATNF) 4 November 2008

Introduction Very Long Baseline Interferometry (VLBI) Combining (correlating) very distant radio telescopes “virtual” large telescope  more resolution == detail “Baseline” = distance  100s-1000s km Interferometry = pair-wise correlation Telescopes widely distributed over countries, continents, even in space. Traditionally: “record” data on tapes or disks & “correlate” later (days or weeks or months) e-VLBI Real-time VLBI using fast network transfers into hardware or software correlators NOBUGS November 2008

LBA Radio Telescopes in Australia x Katherine x New Norcia x Yarragadee x ASKAP x

NOBUGS November 2008 VLBI Astronomy Arrays (c. 2008) o o o o o o o o o o o O New telescopes in last decade x o o o o o

Resolution (==Details) Jupiter and Io as seen from Earth 1 arcmin 1 arcsec 0.05 arcsec arcsec Simulated with Galileo photo Atmosphere gives 1" limit without corrections which are easiest in radio NOBUGS November 2008

Cen A NOBUGS November 2008

Sensitivity NOBUGS November 2008 HST Deep Field Observe weak objects Look into different populations e.g. Hubble Deep Field View much older objects  Look back in time New insights into universe Need similar sensitivity in the radio spectrum

Radio Telescope sensitivity Sensitivity depends on: Size of the telescope - very expensive to increase Radio receivers – limit of state of the art electronics Cryogenically cooled to liquid He temperatures Integration time – limited by clock stability ** Bandwidth  Data rate (after sampling) Most cost effective to achieve!? Most progress in recent years >1 Gbps routinely achieved VLBI data on disks High data rates expensive to support NOBUGS November 2008

e-VLBI – real-time observing over fast networks e-VLBI Transport the VLBI data over fast networks for “real- time” operation  fast response Data rates at 1 Gbps or more are required BUT very expensive commercially  Collaboration with network providers National Research and Education Networks (NREN) E.g. Internet2; DANTE collaboration; AARNet Research in Astronomy & Networking Very high and sustainable datarates (> 12 hours) Testing the speed and reliability of the networks NOBUGS November 2008

e-VLBI Challenges - 1 “last-mile” fibre connectivity Connect remote telescopes to the NREN backbone Fibre build needed - expensive But many institutions already at 1 Gbps Tools and protocols Sustained high rate traffic required TCP/IP needs “fine tuning” to achieve high rates Congestion control can create problems Other protocols needed (UDP; modified TCP & UDP…) Research and development needed NOBUGS November 2008

e-VLBI Challenges - 2 Long intercontinental distances RTT Australia-Europe > 300 ms Routed Ethernet not consistently reliable Dedicated “light-paths” at 1 Gbps Can be “built” over ethernet backbone Require NREN cooperation over many countries e.g. 3 x 1 Gbps Oz-Holland in 2007 Real-time data processing Hardware correlators – new interfaces Software correlators – new developments Supercomputer clusters and “grid” applications NOBUGS November 2008

e-VLBI Achievemnts - EXPReS project connectivity world-wide NOBUGS November 2008

Oz achievements Telescope connectivity at 2 x 1 Gbps $2M fibre to telescopes built by CSIRO University fast connections in Uni Tasmania, Swinburne (Melbourne) & Curtin (Perth) 1 Gbps operation demonstrated within Australia 512 Mbps “production” e-VLBI 512 Mbps operation with Europe (12 hours) in Mbps operation with Japan and China in 2008 Internet2 IDEA award - 10 Gbps link in US for 1 year New fibre-build for new telescope (ASKAP) in WA Construction to commence shortly Research for next generation radio astronomy instruments ( e.g. SKA ~$2B international project) NOBUGS November 2008

Image created by Paul Boven Satellite image: Blue Marble Next Generation, courtesy of NASA Visibible Earth NOBUGS November 2008

Next steps 10 Gbps connectivity NREN backbones already at 10 Gbps Multiple colours possible (many λλ on one fibre) Dynamic circuit allocations Build light-paths and other circuits interactively Systems in test Distributed correlation “grid-like” applications Flexible operations on software NOBUGS November 2008

Lessons learned 1.NREN collaboration critical Must involve networking community Symbiotic relationship – science + networks 2.Network tools development Tools and protocols need development Sustained high data rates over long distances still problematic  “light-paths” 3.Very high data rates are achievable now Almost “infinite” data pipes NREN test circuits at low cost e.g. AARNet “try-before-you-buy” scheme 6-12 months free 1 Gbps+ connectivity! NOBUGS November 2008

“Paradigm shift” – “unlimited” networks?? Current way of science planning Current plans often limited by scarce network resources Researchers assume connectivity the limiting factor Often limit our own visions and horizons  New way of planning? Plan on the science needs assuming almost “infinite” networks!! Fast research networks are arriving very quickly Expand our horizons now! NOBUGS November 2008

Contact Us Phone: or Web: Thank you ATNF Tasso Tzioumis LBA & eVLBI Phone: Web: NOBUGS November 2008