Transcript NLMHEAnet - Internet2

Packet Loss NLM<=>HEAnet
Internet2
High-performance Applications Support
October 31st, 2000
Atlanta, Georgia
Michael Gill
National Library of Medicine (NLM)
Bethesda, Maryland USA
Victor Reijs
HEAnet, Dublin Ireland
Preparation for interactive
multimedia demonstration
• Learning Collaboratory (at NLM) <=> Centre for
Healthcare Informatics (at Trinity College Dublin)
– http://www.cs.tcd.ie/chi/tcdnlm/
• Using MPEG-2 Codecs at each end
– Camvision-2, from Litton Network Access Systems
– 1.5 => 15 Mbit/s, low-latency video
– Litton supplied demo unit for each end
– Loan from TERENA
– NLM later purchased three units
Initial testing
• Early results (March) showed consistent packet loss
– Tools were limited:
• PingPlotter (www.pingplotter.com)
• cv2sim.exe (simulates video loading without hardware codec,
supplied by Litton)
– More than 1% loss destroys acceptable MPEG-2 video
transmission
• Time Zone difference
– USA=>Dublin=+5 hours
Routing/Peerings
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Asymmetrical routing
NLM -> vBNS+ -> Abilene -> DANTE -> HEAnet
First using vBNS+ (over West of America): long delays
NLM -> Abilene -> DANTE -> HEAnet
90 - 100 msec
Rerouting due to upgrading links from OC-3c to OC-12c
Equipment/cable/configuration issues
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Different connectors then ordered cables
Both sides need to be PAL or NTSC
Exploring Huge buffer settings for all routers in path
Ethernet cable rotten
Mismatching ATM PVC configuration
OC-12c fiber had to replaced
Rotten OC-12c ATM interface
Bandwidth
• 34 Mbit/s transatlantic at IP level (T3)
– USA=>HEAnet heavy traffic
• Overbooked ATM link
• QoS: Committed Access Rate (CAR)
– HEAnet=>USA lighter traffic
– Testing during holidays/low-usage hours
• Upgrading
– Teleglobe (OC-3c -> OC-12c)
– Abilene (shared OC-3c -> OC-12c)
– HEAnet (T3 -> OC-3c: 2Q 2001)
Present conclusions
• Chain of networks
– multi kingdom problem
• Check all router interfaces in the whole path
• Operational network management is not run to have very
low (<1%) packet drop
Changed test scenario
• QoS grid
– Service Level Mangers
– Service Access Points
– IPPM measurements
• E.g. Surveyor, RIPE Test Traffic project (both using GPS)
– Proprietary solutions: Chariot/Qcheck by NetIQ
• Install test points in the path
– At server, client and peering locations
– Provide these test points as part of network service
All in a row
• We had all kind of problems
– Formal demonstrations postponed twice
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March 2000: Testing with tools (packet loss)
May 2000: First video pictures (unacceptable quality)
July 2000: Good quality video for a few days!!!
Oct 2000: Unacceptable quality and still testing
– NLM => HEAnet still unacceptable quality
– HEAnet => NLM fairly good on short tests
• Abilene Premium service and HEAnet bandwidth upgrade
• QoS grid needed
Questions?
Michael Gill, [email protected]
Victor Reijs. [email protected]