Adding a meter Openflow entry on 2920-24G

[EnasAhmad]

Hi Gerhard,

I am using iPerf2, here is the requested output: (Still using a 30mbps meter)

iperf -s -i 0.1

WARNING: interval too small, increasing from 0.10 to 0.5 seconds.

------------------------------------------------------------

Server listening on TCP port 5001

TCP window size: 85.3 KByte (default)

------------------------------------------------------------

[  4] local 10.0.0.4 port 5001 connected with 10.0.0.3 port 49565

[ ID] Interval       Transfer     Bandwidth

[  4]  0.0- 0.5 sec   908 KBytes  14.9 Mbits/sec

[  4]  0.5- 1.0 sec   460 KBytes  7.53 Mbits/sec

[  4]  1.0- 1.5 sec   455 KBytes  7.46 Mbits/sec

[  4]  1.5- 2.0 sec   629 KBytes  10.3 Mbits/sec

[  4]  2.0- 2.5 sec   915 KBytes  15.0 Mbits/sec

[  4]  2.5- 3.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  3.0- 3.5 sec   452 KBytes  7.41 Mbits/sec

[  4]  3.5- 4.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  4.0- 4.5 sec   913 KBytes  15.0 Mbits/sec

[  4]  4.5- 5.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  5.0- 5.5 sec   457 KBytes  7.48 Mbits/sec

[  4]  5.5- 6.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  6.0- 6.5 sec   912 KBytes  14.9 Mbits/sec

[  4]  6.5- 7.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  7.0- 7.5 sec   457 KBytes  7.48 Mbits/sec

[  4]  7.5- 8.0 sec   455 KBytes  7.46 Mbits/sec

[  4]  8.0- 8.5 sec   913 KBytes  15.0 Mbits/sec

[  4]  8.5- 9.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  9.0- 9.5 sec   455 KBytes  7.46 Mbits/sec

[  4]  9.5-10.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  0.0-10.1 sec  11.5 MBytes  9.58 Mbits/sec

********************************************************************

iperf -c 10.0.0.4 -i 0.1

WARNING: interval too small, increasing from 0.10 to 0.5 seconds.

------------------------------------------------------------

Client connecting to 10.0.0.4, TCP port 5001

TCP window size:  129 KByte (default)

------------------------------------------------------------

[  4] local 10.0.0.3 port 49565 connected with 10.0.0.4 port 5001

[ ID] Interval       Transfer     Bandwidth

[  4]  0.0- 0.5 sec  1.25 MBytes  21.0 Mbits/sec

[  4]  0.5- 1.0 sec   128 KBytes  2.10 Mbits/sec

[  4]  1.0- 1.5 sec   512 KBytes  8.39 Mbits/sec

[  4]  1.5- 2.0 sec   640 KBytes  10.5 Mbits/sec

[  4]  2.0- 2.5 sec   896 KBytes  14.7 Mbits/sec

[  4]  2.5- 3.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  3.0- 3.5 sec   512 KBytes  8.39 Mbits/sec

[  4]  3.5- 4.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  4.0- 4.5 sec  1.00 MBytes  16.8 Mbits/sec

[  4]  4.5- 5.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  5.0- 5.5 sec   512 KBytes  8.39 Mbits/sec

[  4]  5.5- 6.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  6.0- 6.5 sec   896 KBytes  14.7 Mbits/sec

[  4]  6.5- 7.0 sec   512 KBytes  8.39 Mbits/sec

[  4]  7.0- 7.5 sec   512 KBytes  8.39 Mbits/sec

[  4]  7.5- 8.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  8.0- 8.5 sec   896 KBytes  14.7 Mbits/sec

[  4]  8.5- 9.0 sec   512 KBytes  8.39 Mbits/sec

[  4]  9.0- 9.5 sec   384 KBytes  6.29 Mbits/sec

[  4]  9.5-10.0 sec   512 KBytes  8.39 Mbits/sec

[  4]  0.0-10.1 sec  11.5 MBytes  9.58 Mbits/sec

*************************************************************

I have noticed that the default window size is small, I reran the test with a larger window size:

local 10.0.0.4 port 5001 connected with 10.0.0.3 port 49700

[  4]  0.0- 0.5 sec   908 KBytes  14.9 Mbits/sec

[  4]  0.5- 1.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  1.0- 1.5 sec   455 KBytes  7.46 Mbits/sec

[  4]  1.5- 2.0 sec   455 KBytes  7.46 Mbits/sec

[  4]  2.0- 2.5 sec   912 KBytes  14.9 Mbits/sec

[  4]  2.5- 3.0 sec   455 KBytes  7.46 Mbits/sec

[  4]  3.0- 3.5 sec   457 KBytes  7.48 Mbits/sec

[  4]  3.5- 4.0 sec   615 KBytes  10.1 Mbits/sec

[  4]  4.0- 4.5 sec   913 KBytes  15.0 Mbits/sec

[  4]  4.5- 5.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  5.0- 5.5 sec   779 KBytes  12.8 Mbits/sec

[  4]  5.5- 6.0 sec   458 KBytes  7.51 Mbits/sec

[  4]  6.0- 6.5 sec   913 KBytes  15.0 Mbits/sec

[  4]  6.5- 7.0 sec   455 KBytes  7.46 Mbits/sec

[  4]  7.0- 7.5 sec   457 KBytes  7.48 Mbits/sec

[  4]  7.5- 8.0 sec   455 KBytes  7.46 Mbits/sec

[  4]  8.0- 8.5 sec   912 KBytes  14.9 Mbits/sec

[  4]  8.5- 9.0 sec   455 KBytes  7.46 Mbits/sec

[  4]  9.0- 9.5 sec   457 KBytes  7.48 Mbits/sec

[  4]  9.5-10.0 sec   455 KBytes  7.46 Mbits/sec

[  4] 10.0-10.5 sec   911 KBytes  14.9 Mbits/sec

[  4] 10.5-11.0 sec   455 KBytes  7.46 Mbits/sec

[  4] 11.0-11.5 sec   457 KBytes  7.48 Mbits/sec

[  4] 11.5-12.0 sec   457 KBytes  7.48 Mbits/sec

[  4]  0.0-12.1 sec  14.1 MBytes  9.82 Mbits/sec

***********************************************************************

iperf -c 10.0.0.4 -i 0.1 -w 2.5m

WARNING: interval too small, increasing from 0.10 to 0.5 seconds.

------------------------------------------------------------

Client connecting to 10.0.0.4, TCP port 5001

TCP window size: 2.50 MByte (WARNING: requested 2.50 MByte)

------------------------------------------------------------

[  4] local 10.0.0.3 port 49700 connected with 10.0.0.4 port 5001

[ ID] Interval       Transfer     Bandwidth

[  4]  0.0- 0.5 sec  3.38 MBytes  56.6 Mbits/sec

[  4]  0.5- 1.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  1.0- 1.5 sec   512 KBytes  8.39 Mbits/sec

[  4]  1.5- 2.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  2.0- 2.5 sec   896 KBytes  14.7 Mbits/sec

[  4]  2.5- 3.0 sec   512 KBytes  8.39 Mbits/sec

[  4]  3.0- 3.5 sec   512 KBytes  8.39 Mbits/sec

[  4]  3.5- 4.0 sec   512 KBytes  8.39 Mbits/sec

[  4]  4.0- 4.5 sec   896 KBytes  14.7 Mbits/sec

[  4]  4.5- 5.0 sec   512 KBytes  8.39 Mbits/sec

[  4]  5.0- 5.5 sec   768 KBytes  12.6 Mbits/sec

[  4]  5.5- 6.0 sec   512 KBytes  8.39 Mbits/sec

[  4]  6.0- 6.5 sec   896 KBytes  14.7 Mbits/sec

[  4]  6.5- 7.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  7.0- 7.5 sec   512 KBytes  8.39 Mbits/sec

[  4]  7.5- 8.0 sec   512 KBytes  8.39 Mbits/sec

[  4]  8.0- 8.5 sec   896 KBytes  14.7 Mbits/sec

[  4]  8.5- 9.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  9.0- 9.5 sec   512 KBytes  8.39 Mbits/sec

[  4]  9.5-10.0 sec   384 KBytes  6.29 Mbits/sec

[  4]  0.0-10.0 sec  14.1 MBytes  11.8 Mbits/sec

Not much of a difference.

[Gerhard Roets · Accepted solution]

Hi Enas

Based on the information you provided I can see that you have a classical saw tooth performance pattern.

From the Server you see a typical throughput of

7.5Mbps and Once in a while 15 Mbps. You can also see there is a kind of “rhythm” to it this is the pattern I am talking about.

It is similar from the client side point of view.

This is typical of TCP sessions where there is drops, this is understandable because of how tcp windowing works. The switch simply drops packets when the bucket is full. This causes tcp to react in the way that you see.

One thing you can do is decrease the window size, not increase. So if you make the window size as small as possible you might see different results. In the end though this is an artificial fix as you cannot control all clients individually like this.

The solution for this is to start randomly dropping packets from multiple streams once you detect getting close to the threshold and thus forcing some back off, but this assumes there is multiple streams.

The reason why UDP shows it more correct is that UDP does not have Windowing and TCP Slow start. There are various articles around this that you can find on the web with your web search engine of choice just search for “TCP Slow start”, “TCP Congestion Control”, and “TCP Synchronization”.

Hope this helps

Gerhard Roets

HPE SDN CoE