e -VLBI at ≥ 1 Gbps -- “unlimited” networks?

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

2. 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

3. LBA Radio Telescopes in Australia x Katherine x ASKAP x Yarragadee x New Norcia x NOBUGS November 2008

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

5. Resolution (==Details) Atmosphere gives 1" limit without corrections which are easiest in radio Jupiter and Io as seen from Earth 1 arcmin 1 arcsec 0.05 arcsec 0.001 arcsec Simulated with Galileo photo NOBUGS November 2008

6. Cen A NOBUGS November 2008

7. Sensitivity • 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 HST Deep Field NOBUGS November 2008

8. 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

9. 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

10. 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

11. 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

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

13. 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 2007 • 512 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

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

15. 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

16. Lessons learned • NREN collaboration critical • Must involve networking community • Symbiotic relationship – science + networks • Network tools development • Tools and protocols need development • Sustained high data rates over long distances still problematic  “light-paths” • 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

17. “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

18. Contact Us Phone: 1300 363 400 or +61 3 9545 2176 Email: enquiries@csiro.au Web: www.csiro.au Thank you ATNF Tasso Tzioumis LBA & eVLBI Phone: +61 2 9372 4350 Email: Tasso.Tzioumis@csiro.au Web: www.atnf.csiro.au/vlbi NOBUGS November 2008