1. 1 QoS on Best-effort IP Networks Les Cottrell – SLAC www.slac.stanford.edu/grp/scs/net/talk/qos-itu-apr01/ Presented at the Joint SG13/SG16 Workshop Panel Session: "Achieving Multimedia QOS over IP-Based Networks" part of the ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, Geneva, Switzerland, April 25-27, 2001 Partially funded by DOE/MICS Field Work Proposal on Internet End-to-end Performance Monitoring (IEPM), also supported by IUPAP

2. 2 Overview Measurement methodology Delay Loss Jitter Availability Summary

3. 3 PingER Measurements from –32 monitors in 14 countries –Over 600 remote hosts –Over 72 countries –Over 3300 monitor-remote site pairs –Measurements go back to Jan-95 –Reports on RTT, loss, reachability, jitter, reorders, duplicates … Uses ubiquitous ping facility of TCP/IP Countries monitored –Contain 78% of world population –99% of online users of Internet

4. 4 RTT from ESnet to Groups of Sites ITU G.114 300 ms RTT limit for voice 20%/year RTT ~ distance/(0.6*c) + hops * router delay Router delay = queuing + clocking in & out + processing

5. 5 RTT Region to Region OK White 0-64ms Green 64-128ms Yellow 128-256ms NOT OK Pink 256-512ms Red > 512ms OK within regions, N. America OK with Europe, Japan

6. 6 RTT from California to world Longitude (degrees) 300ms RTT (ms.) Frequency RTT (ms) Source = Palo Alto CA, W. Coast E. Coast US W. Coast US Europe & S. America Europe 3*0.6c Brazil E. Coast Data from CAIDA Skitter project

7. 7 Loss seen from US to groups of Sites ETSI DTR/TIPHON-05001 V1.2.5 threshold for good speech 50% improvement / year

8. 8 Loss to world from US Using year 2000, fraction of worlds population/country from www.nua.ie/surveys/how_many_online/

9. 9 Losses between Regions

10. 10 Jitter from N. America to W. Europe Jitter = IQR(ipdv), where ipdv(i) =RTT(i) – RTT(i-1) 214 pairs ETSI: DTR/TIPHON-05001 V1.2.5 (1998-09) good speech < 75ms jitter

11. 11 Jitter between regions 75ms=Good 125ms=Med225ms=Poor ETSI: DTR/TIPHON-05001 V1.2.5 (1998-09) Jitter varies with loading

12. 12 SLAC-CERN Jitter ETSI/TIPHON delay jitter threshold (75 ms)

13. 13 Availability – Outage Probability Surveyor probes randomly 2/second Measure time (Outage length) consecutive probes dont get through Heavy tailed outage lengths (packet loss not Poisson) http://www-iepm.slac.stanford.edu/monitoring/surveyor/outage.html

14. 14 More Information This talk: –www.slac.stanford.edu/grp/scs/net/talk/qos-itu-apr01/www.slac.stanford.edu/grp/scs/net/talk/qos-itu-apr01/ IEPM/PingER home site –www-iepm.slac.stanford.edu/www-iepm.slac.stanford.edu/