If memory serves me right, Fran Terlingo (fterling) wrote: > IPerf Experts, > > > > I am performing tests between an iPerf 3.1.3 client running on a Linux > Ubuntu Virtual machine on a VMware ESX host and a similar setup with the > iPerf 3.1.3 server VM running on a separate ESX server. The ESX servers > have 10 Gig NICs with plenty of CPU and both connect to a network with a > 40 Gig core. I am able to drive 10 Gbps linerate bandwidth when running > iPerf “TCP” flows between the client and server. However, the most I can > get when running a “UDP” test is roughly 5.5 Gbps transmission rate. I > actually tweaked a couple of iPerf parameters to increase the > transmission rate that ultimately got me to 5.5 Gbps -- but that is all > I can get so far. It doesn’t look like the VMs running iPerf are CPU > bound so it must be the iPerf UDP settings are not optimized.
Sorry for the delay...one suggestion I have is to try running a newer version of iperf3 (3.2 or newer, as 3.2 fixed some problems dealing with the way that UDP packets were paced for sending). > Can someone provide guidance on the optimal iPerf settings to get the > maximum transmission rate when using a UDP flow ?? > > > > Side question: When running iPerf 3.1.3, I was not able use the "-u" > flag on the server as it stated this was an invalid argument. I also > tried changing the listening port as well with no luck. I was able to > have the client set the UDP test and the server was able to accept the > UDP test from the client. I just can’t set the options on the server > side of iPerf 3.1.3 the way I can with the 2.x releases. I'm not sure if > this is something on my end or if this is expected behavior. I also need > to change the port the server listens on and can't get that working when > using the “-p” flag on the server nor when I try to set the server side > port on the client. You don't need to set UDP mode on the server. In iperf3, a control connection is established between the client and server, over which the client sends all of the test parameters (including the protocol). However, specifying the port number with the "-p" option *should* work. > Sorry, just a few more questions. I see there is a way to set the TOS > with the "-S" flag. Is there a way to set the DSCP (Diffserv) marking in > the packet instead of TOS ?? Newer versions of iperf3 (3.2 and newer?) allow you to set the DSCP field in the IP header. > Lastly, is there a way to set the MTU size > of the frame generated by iPerf or possibly even use jumbo frames ?? Use the --length parameter to set the size of UDP sends. If you have jumbo frames configured correctly on the path between client and sender, iperf3 will use them. Bruce.
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