Hi Experts/users, I have a query on the usage of --set-mss flag for TCP streams in iperf3.
For the test purpose I have used the iperf3 public servers(https://iperf.fr/iperf-servers.php) Used wireshark to verify the generated traffic from my end. Below are the different options that I have tried. [bash] > iperf3 -c bouygues.iperf.fr Traffic observed in wireshark: MSS option in SYN packet: 1440 bytes. Total frame size: 1444 bytes. TCP payload size: 1358 bytes. ------------------------------------------------------------------------------------------------------ [bash]> iperf3 -c bouygues.iperf.fr --set-mss 900 Traffic observed in wireshark: MSS option in SYN packet: 900(As expected) Total frame size: 974 bytes TCP payload size: 888 bytes --set-mss flag seems clear effect on the generated traffics as it reduces the TCP payload within 900bytes. ------------------------------------------------------------------------------------------------------- If I set the value more than 1440 bytes, iperf3 never overrides the default value of 1440 bytes in MSS option of the SYN packet. [bash] > iperf3 -c bouygues.iperf.fr --set-mss 2000 Traffic observed in wireshark: MSS option in SYN packet: 1440. Total frame size: 1444 bytes. TCP payload size: 1358 bytes. --------------------------------------------------------------------------------------------------------- Why SYN packet of the last test not set to 2000? Please some explain. Thanks in advance. Regards, Mohan ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Iperf-users mailing list Iperf-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/iperf-users
