2012-09-05 I want to do some network measurements. ...
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I want to do some network measurements. Measuring throughput over tcp or udp is easy: use iperf. Although the iperf server process in daemon mode was using 100% cpu for each(!) measurement somehow, so the load on the machine tested ran up to more than 50. But I am also interested in tcp setup time. It took a bit longer to find something which does that. Searching gave me measure tcp connection setup time: time-gai-connect which was developed to measure differences in IPv4 and IPv6 tcp connection setup times. Interesting answers:$ ./time-gai-connect.py www.google.com 2a00:1450:400c:c05::63 19.62209 ms 18.104.22.168 19.78207 ms 22.214.171.124 20.66183 ms 126.96.36.199 19.69004 ms 188.8.131.52 20.01190 ms 184.108.40.206 20.47896 ms 220.127.116.11 21.71206 msAnd this one is really strange to me... on the machine which runs both the IPv4 address and IPv6 address for idefix.net:$ ./time-gai-connect.py idefix.net 2001:980:14ca:42::18 0.35095 ms 18.104.22.168 0.18501 msYes, the IPv6 tcp connect setup takes longer with IPv6 on this local connection.
I added code to measure resolving time when testing it on my laptop, which now shows shorter times for IPv6 than IPv4, one wireless hop away from the same system.$ ./time-gai-connect.py idefix.net Resolving 3.20196 ms 2001:980:14ca:42::18 0.96989 ms 22.214.171.124 1.49107 msMeasuring this gives more new questions than answers... it seems remote destinations are faster for IPv6 than for IPv4. Example from the same laptop:$ ./time-gai-connect.py www.xs4all.nl Resolving 34.10101 ms 2001:888:0:18::80 15.76281 ms 126.96.36.199 15.84506 msAnd from the system running idefix.net:$ ./time-gai-connect.py www.xs4all.nl Resolving 2.60282 ms 2001:888:0:18::80 14.32490 ms 188.8.131.52 15.16104 ms