1. Packet Loss NLM HEAnet Michael Gill National Library of Medicine (NLM) Bethesda, Maryland USA Victor Reijs HEAnet, Dublin Ireland Internet2 High-performance Applications Support October 31 st, 2000 Atlanta, Georgia

2. 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

3. 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 Initial testing

4. Routing/Peerings 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

5. Equipment/cable/configuration issues 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

6. 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)

7. 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

8. 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

9. All in a row We had all kind of problems –Formal demonstrations postponed twice 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

10. Questions? Michael Gill, mike_gill@nlm.nih.gov Victor Reijs. victor.reijs@heanet.ie