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Networking for ATLAS Remote Farms

Networking for ATLAS Remote Farms. Richard Hughes-Jones The University of Manchester. DataGrid WP7 – Dante Tests on the G ÉANT Core End-2-End Measurements from the 4 th Year VLBI Project at Manchester New TCP stacks – the effect on throughput Some Simple Network Tests CERN-Manchester.

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Networking for ATLAS Remote Farms

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  1. Networking for ATLAS Remote Farms Richard Hughes-Jones The University of Manchester DataGrid WP7 – Dante Tests on the GÉANT Core End-2-End Measurements from the 4th Year VLBI Project at Manchester New TCP stacks – the effect on throughput Some Simple Network Tests CERN-Manchester Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  2. DataGrid WP7 – Dante Tests on the GÉANT Core • Set-up • Supermicro PC in: • London GEANT PoP • Amsterdam GEANT PoP • Smartbits in: • London GEANT PoP • Frankfurt GEANT PoP • Long link UK-SE-DE2-IT-CH-FR-BE-NL • Short Link UK-FR-BE-NL Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  3. Tests GÉANT Core: UDP throughput • UDP Throughput • London-Amsterdam • Available BW to packet on wire • Then 1/t • Wire rate 998 Mbit/s for packets > 1400 bytes • Packet Loss • None for large packets • Dips in BW lined to packet loss • SysKonnect NIC int. per packet • CPU load important Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  4. Tests GÉANT Core: Packet re-ordering • Effect of Packet size • London-Amsterdam • Packets at 10 µs – line speed • 10,000 sent • Packet Loss ~ 0.1% • Re-order Distribution Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  5. Tests GÉANT Core: Packet re-ordering • Effect of LBE background • Amsterdam-London • BE Test flow • Packets at 10 µs – line speed • 10,000 sent • Packet Loss ~ 0.1% • Re-order Distributions: Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  6. Tests GÉANT Core: Packet Jitter • Amsterdam-London • BE Test flow • Packet spacing 80 µs • BE Test flow + Background: 60% BE 1.4Gbit + 40% LBE 780Mbit • IPPremium Test flow + Background • IPPremium Test flow Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  7. Tests GÉANT Core: 1-way Delay • Amsterdam-London • IPPremium Test flow • Packet spacing 80 µs • BE Test flow + Background: 60% BE 1.4Gbit + 40% LBE 780Mbit • BE Test flow + Background: 60% BE 1.4Gbit + 40% LBE 780Mbit Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  8. VLBI Project: Test Topology SURFnet Manchester JIVE Dwingaloo Jodrell SuperJANET4 Adam Mathews Steve O’Toole Univ of Manchester Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  9. VLBI Project: Throughput • Manchester to Dwingeloo • 2.0G Hz Xeon 1.2 GHz PIII • Re-ordering vs Offered Load Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  10. 1-way Delay – note the packet loss (points with 0 –way delay) VLBI Project: Jitter & 1-way Delay • 1472 byte Packets man -> JIVE • FWHM 22 µs (B2B 3 µs ) Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  11. VLBI Project: Packet Loss – Long Range Effects? • 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 Hβ = 2H -2 • Measure:β = -0.355 which gives H 0.822 • H =1 no long range dependence Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  12. Traffic Flows • Manchester – NetNorthWest - SuperJANET Access links • Two 1 Gbit/s • Access links:SJ4 to GÉANT GÉANT to SurfNet Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  13. High Performance TCP – DataTAG • Different TCP stacks tested on the DataTAG Network • 128 ms round trip time • Drop 1 in 106 • High-Speed • Rapid recovery • Scalable • Very fast recovery • Standard • Recovery would take ~ 10 mins Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  14. MB-NG Managed Bandwidth High Performance TCP – MB-NG • Drop 1 in 25,000 • Rtt 6.2 ms • Recover in 1.6 s Standard HighSpeed Scalable Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  15. Zero stats OK done Request event Send event data Request-Response time (Histogram) ●●● ●●● Get remote statistics Send statistics: CPU load & no. int 1-way delay Some Network Tests • TCP Request – Response Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  16. Lab Test: TCP Request-Response Histograms • PC – router – PC • BE Test flow • Request spacing 0 µs • Request spacing 10 ms Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  17. Man-CERN: TCP Request-Response Latency • DataTAG PC – backup link • BE Tests • Request spacing 0 µs • Win size 2.5Mbytes • Compare with UDP latency • Large differences • Rtt of 20 msdelay*bw = 2.5 Mbytes • 1Mbyte data = 690 pkts  interesting bursts ! Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  18. Man-CERN: UDP Throughput & Packet Loss • DataTAG PC – backup link • BE Tests • Throughput • Packet loss Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  19. Traffic Flows • Manchester – NetNorthWest - SuperJANET Access links • Link to PC in M/c • Access links: • 1 GE Man to NNW • Total Man to NNW • NNW to SuperJANET4 Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  20. Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  21. VLBI Project: Packet Loss – Is it Poisson? • Divide time series of packets into 1000 slices of 50 packets • Total lost packets 1410 • Average number / slice = 1.4 • Calc Poisson ProbabilityP(n, µ) = µ n e -µ n! • Curves close but not exact • Could be more than 1 process Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  22. Traffic QoS Classes on GÉANT Backbone Max Throughput on 2.5 G PoS • Normal Traffic + • Radio Astronomy Data + • Less Than Best Effort • 2.0 Gbit/s • Normal Traffic + • Less Than Best Effort • 2.0 Gbit/s • Normal Traffic + • Radio Astronomy Data • 500 Mbit/s • Normal Traffic Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

  23. Some Measurements made during ER2002 Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004 R. Hughes-Jones Manchester

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