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1The impact of lossy networks on TCP performance
2===============================================
3
4Jeff Silverman (jeffsilverm at- gmail.com)
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6questions to answer
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8
9How well does TCP cope with loss?
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11How does TCP on IPv4 vs. IPv6 behave?
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13
14tools
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16
17Using `tc` to create latency & loss.
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19post-processing in jupyter, pandas, numpy, scipy, matplotlib (graphs)
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21
22Findings
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24
25*  Quite resilient even in 3/5 60% packet loss
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27*  IPv4/IPv6 
28  - no real difference on LAN
29  - WAN IPv4 worked better, but CenturyLink IPv6 was in encapsulation
30
31*  80% loss & 500ms delay - still worked
32*  failures are not deterministic - delay not constinent with what `tc` set
33*  some uncaught failures were actually DNS
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35
36Data
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38
39504 runs
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41ipv4 failed 9 times (3.6%)
42IPv6 failed 19 times (7.5%)
43failures non-deterministic - not correlated to conditions
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45Size wasn't a predictable indicator of failures
46
47* global tcp retransmits from `netstat -s` from all connections