VLBI%20

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VLBI Protocolsvlbi_udp Multiple Flow Tests
Richard Hughes-Jones The University of
Manchester www.hep.man.ac.uk/rich/ then
Talks
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Setting up the Tests

• Thank you to the people at all the sites for your
  help and making facilities available
• Including
• Onsala
• JIVE
• Torun and Pioner Poznan
• GARR Bologna
• Jodrell and Manchester Network Group
• Dante

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vlbi_udp Multi-site Streams
Gbit link
Chalmers University of Technology, Gothenburg
Metsähovi
OnsalaSweden
Jodrell BankUK
Gbit link
TorunPoland
DedicatedGbit link
Dwingeloo DWDM link
MedicinaItaly
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vlbi_udp UDP on the WAN

• iGrid2002 monolithic code
• Convert to use pthreads
• control
• Data input
• Data output
• Code branch for Simons file transfer tests
• Work on vlbi_recv
• Output thread polled for data in the ring buffer
  burned CPU
• Input thread signals output thread when there is
  work to do else wait on semaphore packet loss
  at high rate, variable thoughput
• Output thread uses sched_yield() when no work to
  do
• Multi-flow Network performance being set up
  Nov/Dec06
• 3 Sites to JIVE manc UKLight Manc production
  Bologna GEANT PoP
• Measure throughput, packet loss, re-ordering,
  1-way delay
• To do
• Add code for MarkV card and PCEVN interface

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vlbi_udp Some of the Problems

• JIVE made Huygens, mark524 (.54) and mark620
  (.59) available
• Within minutes of Arpad leaving the Alteon NIC of
  mark524 lost the data network!
• OK used mark623 (.62) faster CPU
• Firewalls needed to allow vlbi_udp ports
• Aarrgg (!!!) Huygens is SUZE Linux
• Routing well this ALWAYS needs to be fixed !!!
• AMD Opteron did not like sched_getaffinity()
  sched_setaffinity()
• Comment out this bit
• udpmon flows Onsala to JIVE look good
• udpmon flows JIVE mark623 to Onsala Manc UKL
  dont work
• Firewall down stops after 77 udpmon loops
• Firewall up udpmon cant communicate with Onsala
• CPU load issues on the markV systems
• Dont seem to be able to keep up with receiveing
  UDP flow AND emptying the ring buffer
• Torun PC / Link lost during the tests

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vlbi_udp Onsala ? mark623

• It worked !

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Multiple vlbi_udp Flows

• Gig7 ? Huygens UKLight 15 us spacing 800 Mbit/s
• Gig8 ? mark623 Academic Internet 20 us spacing
  600 Mbit/s
• Bologna ? mark620 Academic Internet 30 us spacing
  400 Mbit/s

SJ5 Access link
SURFnet Access link
GARR Access link
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Multiple vlbi_udp Flows

• Gig7 ? Huygens UKLight 15 us spacing
• 816 Mbit/s del lt1Mbit/sstep 1 Mbit/s
• Zero packet loss
• Zero re-ordering
• Gig8 ? mark623 Academic Internet 20 us spacing
• 612 Mbit/s
• 0.6 falling to 0.05 packet loss
• 0.02 re-ordering
• Bologna ? mark620 Academic Internet 30 us
  spacing
• 396 Mbit/s
• 0.02 packet loss
• 0 re-ordering

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• Any Questions?

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• Backup Slides