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QoS on Best-effort IP Networks. Les Cottrell – SLAC www.slac.stanford.edu/grp/scs/net/talk/qos-itu-apr01/

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qos on best effort ip networks

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

overview
Overview
  • Measurement methodology
  • Delay
  • Loss
  • Jitter
  • Availability
  • Summary
pinger
PingER

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
rtt from esnet to groups of sites
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

rtt region to region
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

rtt from california to world
RTT from California to world

Europe

E. Coast

Brazil

E. Coast US

W. Coast US

300ms

RTT (ms)

Europe & S. America

3*0.6c

Longitude (degrees)

300ms

Frequency

Source = Palo Alto CA, W. Coast

RTT (ms.)

Data from CAIDA Skitter project

loss seen from us to groups of sites
Loss seen from US to groups of Sites

50% improvement / year

ETSI DTR/TIPHON-05001 V1.2.5 threshold for good speech

loss to world from us
Loss to world from US

Using year 2000, fraction of world’s

population/country from

www.nua.ie/surveys/how_many_online/

jitter from n america to w europe
“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

jitter between regions
“Jitter” between regions

ETSI: DTR/TIPHON-05001 V1.2.5 (1998-09)

125ms=Med

225ms=Poor

75ms=Good

Jitter varies with loading

slac cern jitter
SLAC-CERNJitter

ETSI/TIPHON delay

jitter threshold

(75 ms)

availability outage probability
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)

http://www-iepm.slac.stanford.edu/monitoring/surveyor/outage.html

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