1
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2
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- Performance is improving
- Developed world improving factor of 10 in 4-5 years
- S.E. Europe, C.Asia Russia, catching up
- India & Africa worse off & falling behind
- Developing world 3-10 years behind
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3
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4
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5
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6
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- red line is the cross-traffic
- deduced by looking at the variation over and above the minimum packet
pair separation, the
- green line is the bandwidth capacity of current bottleneck
- deduced from the minmum packet separation
- blue line is available bandwidth = capacity-cross-traffic.
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7
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- Transfer time to send a file of various sizes between 2 sites with given
capacity
- assume can utilize 50% of capacity
- format hours:mins:seconds
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8
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- Voice needs RTT < 250ms or else listener does not know when to speak
- RTT > 400ms makes productive interactive work such as interactive
telnet/X-windows style typing difficult
- Screen does not match the keyboard, especially when correcting text
- Losses:
- Losses > 10% TCP connections fail
- Losses >4-6% make video conferencing unintelligible for non-native
language speakers
- Losses of > 3-5% make TCP perform badly
- Random loss of 2.5% will make Voice over IP annoying every 30 seconds
or so
- More realistic burst losses will cause VoIP to be annoying at >1%
losses
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9
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- ABwE available bandwidth estimator
- www-iepm.slac.stanford.edu/bw/abwe/abwe-cf-iperf.html
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