1. Connect. Communicate. Collaborate Support by GÉANT2 and NRENs for eVLBI in Europe John Chevers, DANTE In collaboration with: Toby Rodwell (DANTE) Steve Parsley, Arpad Szomoru (Joint Institute for VLBI in Europe) Paul Burgess, Simon Casey, Richard Hughes-Jones, Adam Mathews, Stephen O’Toole, Ralph Spencer (University of Manchester) TNC2005 Poznan, Poland 8 th June 2005

2. Connect. Communicate. Collaborate User Support in GÉANT2 GÉANT2 has 3 million+ users in 34 countries in Europe and beyond How to support them? Pan-European projects with ‘demanding’ requirements –International user groups –High bandwidth requirement? –Specialised service requirement? Aim to introduce new levels of accountability, transparency and service Custom solutions for the particular user group To manage the lifecycle of the networking aspects of each user project Customer focused

3. Connect. Communicate. Collaborate User Support Mechanism for GÉANT2 Initial Contact –Establish eligibility of user application –Inform all NRENs involved –Assign point of contact User Questionnaire –Requirement gathering Evaluation –Consultation between DANTE and NRENs –Define stakeholders

4. Connect. Communicate. Collaborate User Support Mechanism for GÉANT2 (II) Planning and Implementation –Action plan –Design of OPN –Risk Register Continued Support –A service charter for the user –Change management QUALITY OF CUSTOMER SERVICE IS VITAL!

5. Connect. Communicate. Collaborate Networking for eVLBI in Europe European eVLBI Network: collaboration of radio observatories in Europe, Asia and South Africa Presently 5 telescopes connected: Torun, Onsala, Cambridge, Westerbork, Jodrell Bank Many more to be connected soon Large data flows, monitoring required A demanding user!

6. Connect. Communicate. Collaborate The future of the distant past: using networks for VLBI Connecting observatories to create a telescope as big as Europe! Continental-scale baselines produce the most detailed images ever of the most distant objects! Improving the resolution of observations to see further back in time Eliminating out-moded tape technology and speeding up results Harnessing the power of many radio telescopes in real time – only possible with GÉANT2 Allowing new ‘Window of Opportunity’ experiments: dynamic scheduling Distributing results to users across the world

7. Connect. Communicate. Collaborate GÉANT2/NREN eVLBI Network Connect. Communicate. Collaborate se1 - Juniper uk1 - Juniper nl1 - Juniper cz1 - Juniper pl1 - Juniper de1 - Juniper it1- Juniper de2 - Juniper STM-64 (10Gbps) ws4.it Dell geant-gw3 lond-scr3 man'-bar Cisco warr-scr Cisco read-scr3 Milan GSR Bologna GSR Bologna GARR bwctlMk5 MB STM-16 (2.5Gbps) Gigabit Ethernet ManCompCen Transmode 3Com CR1 JIVE, NL JODRELL BANK, UK Mk5s BOLOGNA, IT ws4.uk Dell Mk5 Torun oso-gw chalmers2 goteborg2 boras2 jonkoping1stockholm1 stockholm2 se-kth Mk5 Cisco ONSALA, SE TORUN, PL Unknown Netherlight

8. Connect. Communicate. Collaborate GÉANT2 User Support for eVLBI The EVN-NREN forum: the communities meet face-to-face! –Planning –Problem solving –Discussion of results –Increasing understanding GÉANT Weathermap and Taxametro tools Counters on GÉANT links Diagnostic tools (BWCTL) in GÉANT and NREN network nodes PERT account created –letting SMEs loose on the problem! Also use of specialised tools eg UDPmon

9. Connect. Communicate. Collaborate Progress in eVLBI 2004-2005 01/04 First disc-buffered eVLBI image 04/04 Three-telescope eVLBI session 06/04 eVLBI network stress tests (iPerf) 09/04 4 telescope eVLBI 09/04 First real-science eVLBI 12/04 Fringes at 256 Mbps JB-Tr 02/05 Network data transfer tests (BWCTL) between 6 eVLBI sites 03/05 eVLBI science session involving 6 telescopes: Wb, Ar, JB, Cm, On, Tr 03/05 EXPReS Proposal: –‘Production’ eVLBI –16 telescopes –High Data Rates –Global eVLBI 06/05 Connection of Medicina observatory: brings total to 6 telescopes in 5 countries across Europe

10. Connect. Communicate. Collaborate 4 th Year MPhys Project Adam Mathews Steve O’Toole Throughput vs packet spacing Manchester: 2.0 GHz Xeon Dwingeloo: 1.2 GHz PIII Near wire rate, 950 Mbps Packet loss CPU Kernel Load Receiver UDP Throughput Nov 2003 Manchester-SuperJANET4-GEANT-Surfnet-Dwingeloo Effect on local traffic

11. Connect. Communicate. Collaborate 1472 byte Packets man -> JIVE Relative 1-way delay Packet Loss & 1-way Delay

12. Connect. Communicate. Collaborate Measure the time between lost packets in the time series of packets sent. Lost 1410 in 0.6s Is it a Poisson process? Assume Poisson is stationary λ(t) = λ Use Prob. Density Function: P(t) = λ e -λt Mean λ = 2360 / s [426 µs] Plot log: slope -0.0028 expect -0.0024 Could be additional process involved Packet Loss Distribution Is it Poisson?

13. Connect. Communicate. Collaborate eVLBI Data Transfers over GÉANT: Long term tests of Bandwidth Jodrell-UKERNA-GÉANT-SURFnet-JIVE

14. Connect. Communicate. Collaborate eVLBI Data Transfers over GÉANT: Long term tests of Packet Loss Jodrell-UKERNA-GÉANT-SURFnet-JIVE 6 runs out of 747 showed any loss 1097 packets lost out of 81 million sent – 1.3x10 -3 %

15. Connect. Communicate. Collaborate UDP Tests Jan 2005 Simon Casey (PhD project) Between JBO and JIVE in Dwingeloo, using production network Period of high packet loss (3%):

16. Connect. Communicate. Collaborate GEANT – UKLight Comparison May 2005 Simon Casey (PhD project) Between JBO and JIVE in Dwingeloo Using production network Using UKLight network

17. Connect. Communicate. Collaborate Results of Jodrell-JIVE eVLBI Transfer Tests Overall link quality Manchester/Jodrell to JIVE very good – near line rate possible Occasional negligible losses, very infrequent noticeable losses Packet re-ordering observed Monitoring equipment will help to discover point in the link where losses occur These tests had no ‘exclusive’ access to machines – possible for other users to have an effect Real eVLBI sessions should be able to control access of machines

18. Connect. Communicate. Collaborate Conclusions and the FUTURE Data rates of 256Mbps feasible on real eVLBI runs Data rates of 900Mbps possible with UDP protocol The EXPRes EU eVLBI proposal: 16 telescopes in Europe, Asia, Australia, Latin America and North America JBO-Onsala test link at 4 Gbps, submitted March 19 th 2005 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 eVLBI will be routine in 2006!!

19. Connect. Communicate. Collaborate Backup Slides

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

21. Connect. Communicate. Collaborate Divide time series of packets into 1000 slices of 50 packets Total lost packets 1410 Average number / slice = 1.4 Calc Poisson Probability P(n, µ) = µ n e -µ n! Curves close but not exact Could be more than 1 process VLBI Project: Packet Loss – Is it Poisson?

22. Connect. Communicate. Collaborate Aggregated Variance Method Divide time series length N into blocks of size m Calc mean of each section Xm(k) k= 1 … N/m Calc variance VXm of these Xm(k) Vary m size of the blocks Plot on log-log & fit slope β Hurst parameter H β = 2H -2 Measure: β = -0.355 H 0.822 H =1 no long range dependence VLBI Project: Packet Loss – Long Range Effects?