1. High Data Rate Transfer for HEP and VLBI Ralph Spencer, Richard Hughes-Jones and Simon Casey The University of Manchester Netwrokshop33 March 2005

2. HEP: The LHC Detectors CMS ATLAS LHCb ~6-8 PetaBytes / year ~10 8 events/year

3. Radio Astronomy The study of celestial objects at 1m wavelength. Sensitivity for continuum sources B=bandwidth,  integration time. High resolution achieved by interferometers. Some radio emitting X-ray binary stars in our own galaxy: GRS 1915+105 MERLIN SS433 MERLIN and European VLBI Cygnus X-1 VLBA

4. Earth-Rotation Synthesis Need ~ 12 hours for full synthesis, not necessarily collecting data for all that time. NB Trade-off between B and  for sensitivity. Telescope data correlated in pairs: N(N-1)/2 baselines Merlin u-v coverage

5. The European VLBI Network EVN Detailed radio imaging uses antenna networks over 100s-1000s km At faintest levels, sky teems with galaxies being formed Radio penetrates cosmic dust - see process clearly Telescopes in place … Disk recording at 512Mb/s real-time connection allows greater –response –reliability –sensitivity

6. Westerbork Netherlands Dedicate d Gbit link EVN-NREN Onsala Sweden Gbit link Jodrell Bank UK Dwingeloo DWDM link Cambridge UK MERLIN Medicina Italy Chalmers University of Technolog y, Gothenbur g Torun Poland Gbit link

7. eVLBI Milestones January 2004: Disk buffered eVLBI session: Three telescopes at 128Mb/s for first eVLBI image On – Wb fringes at 256Mb/s April 2004: Three-telescope, real-time eVLBI session. Fringes at 64Mb/s First real-time EVN image - 32Mb/s. September 2004: Four telescope real-time eVLBI Fringes to Torun and Arecibo First EVN, eVLBI Science session January 2005: First “dedicated light-path” eVLBI ??Gbyte of data from Huygens descent transferred from Australia to JIVE Data rate ~450Mb/s

8. 20 December 20 2004 connection of JBO to Manchester by 2 x 1 GE eVLBI tests between Poland Sweden UK and Netherlands at 256 Mb/s February 2005 TCP and UDP memory – memory tests at rates up to 450 Mb/s (TCP) and 650 Mb/s (UDP) Tests showed inconsistencies betweeb Red Hat kernals, rates of 128 Mb/s only obtained on 10 Feb Haystack (US) – Onsala (Sweden) runs at 256 Mb/s 11 March Science demo JBO telescope winded off, short run on calibrator source done Test needs to be repeated!

10. Jodrell Bank UK Onsala Sweden Medicina Italy Torun Poland Effelsberg Germany Westerbork Netherlands Telescope connections JIVE 1Gb/s 155Mb/s MERLIN Cambridge UK 2.5Gb/ s 1Gb/s MERLIN e ? ? ? ? ?

11. Tests on the Network, Manchester- Dwingeloo: investigation of packet loss 4 th year MPhys Project at The Univertsity of Manchester Oct-Dec 2003, using campus network and SuperJANET 4 academic network in the UK. UDPmon used to test throughput and packet loss NB tune up the end machines – see http://grid.ucl.ac.uk/NFNN.html Effect on the local traffic:

12. Throughput vs packet spacing Manchester: 2.0G Hz Xeon Dwingeloo: 1.2 GHz PIII Near wire rate, 950 Mbps NB record stands at 6.6 Gbps SLAC-CERN Packet loss CPU Kernel Load sender CPU Kernel Load receiver 4 th Year project Adam Mathews Steve O’Toole UDP Throughput Manchester-Dwingeloo (Nov 2003)

13. Packet loss distribution: Cumulative distribution Cumulative distribution of packet loss, each bin is 12  sec wide Long range effects in the data? Poisson

14. 26 th January 2005 UDP Tests Simon Casey (PhD project) Between JBO and JIVE in Dwingeloo, using production network Period of high packet loss (3%):

15. The Future: eVLBI tests in EVN at ~ 1 per month Network tests at up to 950 Mb/s – statistics of packet loss Investigate alternatives to TCP/UDP – tsunami, VSI-E etc. ESLEA tests on MB-NG and UKLight EXPRes EU eVLBI proposal including distributed processing, JBO-Onsala test link at 4 Gbps, submitted March 19 th 2005 eVLBI will be routine in 2006!!

16. Processing Nodes Controller/Data Concentrator VLBI Correlation: GRID Computation task

17. Questions ?