QoS on Best-effort IP Networks - PowerPoint

							    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   1
                  Performance Monitoring (IEPM), also supported by IUPAP
                  Overview
•   Measurement methodology
•   Delay
•   Loss
•   Jitter
•   Availability
•   Summary




                              2
              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
                                                              3
RTT from ESnet to Groups of Sites
RTT ~ distance/(0.6*c) + hops * router delay
Router delay = queuing + clocking in & out + processing


      ITU G.114 300 ms RTT limit for voice




                      20%/year

                                                          4
           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   5
            RTT from California to world




                                               E. Coast
                                                                    Europe




                                                           Brazil
               Europe & S. America
                         RTT (ms)
                                       300ms



                                                                     3*0.6c
Frequency




                                                   Longitude (degrees)
                                     300ms




             RTT (ms.)                                                                  6
                                                          Data from CAIDA Skitter project
Loss seen from US to groups of Sites




  ETSI DTR/TIPHON-05001 V1.2.5 threshold for good speech   7
  Loss to world from US
Using year 2000, fraction of world’s
population/country from
www.nua.ie/surveys/how_many_online/




                                       8
Losses between Regions




                         9
“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
                                                                10
            “Jitter” between regions




ETSI: DTR/TIPHON-05001 V1.2.5 (1998-09)
75ms=Good    125ms=Med       225ms=Poor
Jitter varies with loading                11
                                                                     SLAC-CERN
                                                                        Jitter
                                                                              ETSI/TIPHON delay
                                                                                jitter threshold
                                                                                     (75 ms)
                           IQR(ipdv) between CERN & SLAC from Surveyor measurements
                                          (12/15/98 & medians for Dec-98)

                                IQR(ipdv) CERN>SLAC           IQR(ipdv) SLAC>CERN
                     100
IQR(IPDV) in msec.




                                Monthly IQR(ipdv) CERN>SLAC   Monthly IQR(ipdv) SLAC>CERN

                     10



                      1



                     0.1
                           0            5             10        15            20            25
                                              Time since midnight (GMT)                          12
     Availability – Outage Probability
 Surveyor probes randomly 2/second
 Measure time (Outage length) consecutive probes don’t get
 through
 Heavy tailed outage lengths (packet loss not Poisson)




                                                                    13
http://www-iepm.slac.stanford.edu/monitoring/surveyor/outage.html
                  More Information
• This talk:
  – www.slac.stanford.edu/grp/scs/net/talk/qos-itu-apr01/
• IEPM/PingER home site
  – www-iepm.slac.stanford.edu/




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