#14 Doubts regarding Jperf

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nobody
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5
2010-12-21
2010-12-21
Nuno Silva
No

I need some help from you, in the way that we use jperf to determine possible network delays.
From the point of view of the jperf logs I can see that there are some, actually.

[1912] 1038.0-1040.0 sec 2.87 KBytes 11.8 Kbits/sec 0.955 ms 0/ 2 (0%)
[ ID] Interval Transfer Bandwidth
[1868] 1040.0-1042.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1040.0-1042.0 sec 2.87 KBytes 11.8 Kbits/sec 1.760 ms 0/ 2 (0%)
[1868] 1042.0-1044.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1042.0-1044.0 sec 2.87 KBytes 11.8 Kbits/sec 3.439 ms 0/ 2 (0%)
[1868] 1044.0-1046.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1044.0-1046.0 sec 2.87 KBytes 11.8 Kbits/sec 3.939 ms 0/ 2 (0%)
[1868] 1046.0-1048.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1046.0-1048.0 sec 2.87 KBytes 11.8 Kbits/sec 4.383 ms 0/ 2 (0%)
[1868] 1048.0-1050.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1048.0-1050.0 sec 2.87 KBytes 11.8 Kbits/sec 3.857 ms 0/ 2 (0%)
[1868] 1050.0-1052.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1050.0-1052.0 sec 2.87 KBytes 11.8 Kbits/sec 3.396 ms 0/ 2 (0%)
[1868] 1052.0-1054.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1052.0-1054.0 sec 2.87 KBytes 11.8 Kbits/sec 2.990 ms 0/ 2 (0%)
[1868] 1054.0-1056.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1054.0-1056.0 sec 2.87 KBytes 11.8 Kbits/sec 2.633 ms 0/ 2 (0%)
[1868] 1056.0-1058.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1056.0-1058.0 sec 2.87 KBytes 11.8 Kbits/sec 2.320 ms 0/ 2 (0%)
[1868] 1058.0-1060.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1058.0-1060.0 sec 2.87 KBytes 11.8 Kbits/sec 2.044 ms 0/ 2 (0%)
[ ID] Interval Transfer Bandwidth
[1868] 1060.0-1062.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1060.0-1062.0 sec 2.87 KBytes 11.8 Kbits/sec 1.802 ms 0/ 2 (0%)
[1868] 1062.0-1064.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1062.0-1064.0 sec 2.87 KBytes 11.8 Kbits/sec 1.589 ms 0/ 2 (0%)
[1868] 1064.0-1066.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1064.0-1066.0 sec 2.87 KBytes 11.8 Kbits/sec 1.402 ms 0/ 2 (0%)
[1868] 1066.0-1068.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1066.0-1068.0 sec 2.87 KBytes 11.8 Kbits/sec 1.238 ms 0/ 2 (0%)
[1868] 1068.0-1070.0 sec 2.87 KBytes 11.8 Kbits/sec
[1912] 1068.0-1070.0 sec 2.87 KBytes 11.8 Kbits/sec 1.093 ms 0/ 2 (0%)

This is a bad scenario. Normally it is around 0.045 ms. The thing is that at the same time I was running Wireshark tool, and when I go to the IO Graphs, under the statistics Menu, I get a constant rate.

With this I get different conclusions. I what way you determine those 2.990 ms of delay?

Can you help us understand how can this be read, and what conclusions can we take from it, assuming that we have Wireshark and the graph is a straight line?

The test we performed was using UDP packets.

Note: the Jperf graph also showed me always a straight line.

Best regards,

Nuno Pedro Silva

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