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I am using iperf tool to benchmark my network interfaces on two identical machines (Dell Blade Server M620). Both have given different results.

  • On 1st machine, I ran server and clients as:

Server ==> iperf -s -B 172.17.250.200

Server listening on TCP port 5001 Binding to local address 172.17.250.200 TCP window size: 85.3 KByte (default) ----------------------------------------

client on new shell==> iperf -c 172.17.250.200 -u -i l -b 250m,

WARNING:interval too small, increasing from 0.00 to 0.5 seconds -----------------------------------------------------------

Client connecting to 172.17.250.200, UDP port 5001
Sending 1470 byte datagrams 
UDP buffer size:  208 KByte (default)
------------------------------------------------------------
[  3] local 172.17.250.200 port 56853 connected with 172.17.250.200 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 0.5 sec  7.45 MBytes   125 Mbits/sec 
[  3]  0.5- 1.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  1.0- 1.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  1.5- 2.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  2.0- 2.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  2.5- 3.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  3.0- 3.5 sec  7.43 MBytes   125 Mbits/sec
[  3]  3.5- 4.0 sec  7.44 MBytes   125 Mbits/sec
[  3]  4.0- 4.5 sec  7.46 MBytes   125 Mbits/sec
[  3]  4.5- 5.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  5.0- 5.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  5.5- 6.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  6.0- 6.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  6.5- 7.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  7.0- 7.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  7.5- 8.0 sec  7.44 MBytes   125 Mbits/sec
[  3]  8.0- 8.5 sec  7.46 MBytes   125 Mbits/sec
[  3]  8.5- 9.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  9.0- 9.5 sec  7.46 MBytes   125 Mbits/sec
[  3]  9.5-10.0 sec  7.44 MBytes   125 Mbits/sec
[  3]  0.0-10.0 sec   149 MBytes   125 Mbits/sec`

  • On 2nd machine, I ran with same configuration, I got these results:

    Server==> iperf -s -B 172.17.250.190

    client on new shell==> iperf -c 172.17.250.190 -u -i l -b 250m 

    WARNING: interval too small, increasing from 0.00 to 0.5 seconds.
------------------------------------------------------------
Client connecting to 172.17.250.190, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size:  208 KByte (default)
------------------------------------------------------------
[  3] local 172.17.250.190 port 59887 connected with 172.17.250.190 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 0.5 sec  3.00 MBytes  50.3 Mbits/sec
[  3]  0.5- 1.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  1.0- 1.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  1.5- 2.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  2.0- 2.5 sec  7.05 MBytes   118 Mbits/sec
[  3]  2.5- 3.0 sec  2.95 MBytes  49.5 Mbits/sec
[  3]  3.0- 3.5 sec  2.96 MBytes  49.7 Mbits/sec
[  3]  3.5- 4.0 sec  2.95 MBytes  49.5 Mbits/sec
[  3]  4.0- 4.5 sec  2.97 MBytes  49.8 Mbits/sec
[  3]  4.5- 5.0 sec  2.96 MBytes  49.7 Mbits/sec
[  3]  5.0- 5.5 sec  2.88 MBytes  48.3 Mbits/sec
[  3]  5.5- 6.0 sec  2.88 MBytes  48.3 Mbits/sec
[  3]  6.0- 6.5 sec  2.89 MBytes  48.5 Mbits/sec
[  3]  6.5- 7.0 sec  2.92 MBytes  49.0 Mbits/sec
[  3]  7.0- 7.5 sec  2.94 MBytes  49.3 Mbits/sec
[  3]  7.5- 8.0 sec  2.93 MBytes  49.2 Mbits/sec
[  3]  8.0- 8.5 sec  2.95 MBytes  49.5 Mbits/sec
[  3]  8.5- 9.0 sec  2.95 MBytes  49.5 Mbits/sec
[  3]  9.0- 9.5 sec  2.94 MBytes  49.3 Mbits/sec

why is there a discrepencie in two machine results, they are identical machines. One machine shows stable 125Mbit/sec traffic and other one shows fluctuating traffic.?
I have also tried to use ip-address '127.0.0.1' on both machine with iperf, still I am facing similar issues. In the case of loopback, I think traffic wont be passed through NIC, but there is still fluctuation on loopback too. Both machines are running Ubuntu 12.04 Server 64bit. Any help what could be gone wrong would be appreciated.

Waqas
  • 131
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0 Answers0