What steps will reproduce the problem? 1. recompile the 3.0 code as published on the website 2. on the server run: iperf3 --server 3. on the client run: iperf3 -c <server ip> -V -R -u

What is the expected output? What do you see instead? Expected: 10 seconds continous transfer from server to client

I always get only transfer for the first second:

[root@intratest132 ~]# iperf3 -c 172.16.1.133 -V -R -u iperf version 3.0-RC5 (07 November 2013) Linux intratest132.net.lan 3.4.51-1.i2n.i686.PAE #1 SMP Fri Jun 28 13:49:25 UTC 2013 i686 i686 i386 GNU/Linux Time: Tue, 19 Nov 2013 23:47:54 GMT Connecting to host 172.16.1.133, port 5201 Reverse mode, remote host 172.16.1.133 is sending Cookie: intratest132.net.lan.1384904874.4978 [ 4] local 172.16.1.132 port 50775 connected to 172.16.1.133 port 5201 Starting Test: protocol: UDP, 1 streams, 8192 byte blocks, omitting 0 seconds, 10 second test [ ID] Interval Transfer Bandwidth [ 4] 0.00-1.00 sec 8.00 KBytes 65.5 Kbits/sec
[ 4] 1.00-2.00 sec 0.00 Bytes 0.00 bits/sec
[ 4] 2.00-3.00 sec 0.00 Bytes 0.00 bits/sec
[ 4] 3.00-4.00 sec 0.00 Bytes 0.00 bits/sec
[ 4] 4.00-5.00 sec 0.00 Bytes 0.00 bits/sec
[ 4] 5.00-6.00 sec 0.00 Bytes 0.00 bits/sec
[ 4] 6.00-7.00 sec 0.00 Bytes 0.00 bits/sec
[ 4] 7.00-8.00 sec 0.00 Bytes 0.00 bits/sec
[ 4] 8.00-9.00 sec 0.00 Bytes 0.00 bits/sec
[ 4] 9.00-10.00 sec 0.00 Bytes 0.00 bits/sec

Test Complete. Summary Results: [ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams [ 4] 0.00-10.00 sec 8.00 KBytes 6.55 Kbits/sec 34940.621 ms 0/1 (0%) [ 4] Sent 1 datagrams CPU Utilization: local/receiver 99.6%, remote/sender 68.3%

iperf Done.

What version of the product are you using? On what operating system? recompiled from the published 3.0.tar.gz 32bit linux without ipv6 on both machines.

Something 'not right with your set-up; works for me (on a pair of HP ProBook 8470w running Ubuntu 12.04, patched with 'send-to-self'; connected back-to-back via the motherboard ethernet port).

./iperf3 -c 192.168.3.5 -V -R -u iperf version 3.0-RC5 (07 November 2013) Linux HP-Lab1 3.2.51-send2self #1 SMP Tue Nov 12 11:45:32 GMT 2013 x86_64 x86_64 x86_64 GNU/Linux Time: Fri, 22 Nov 2013 00:12:57 GMT Connecting to host 192.168.3.5, port 5201 Reverse mode, remote host 192.168.3.5 is sending Cookie: HP-Lab1.1385079177.043596.3265039e3e [ 4] local 192.168.3.1 port 52838 connected to 192.168.3.5 port 5201 Starting Test: protocol: UDP, 1 streams, 8192 byte blocks, omitting 0 seconds, 10 second test [ ID] Interval Transfer Bandwidth [ 4] 0.00-1.00 sec 136 KBytes 1.11 Mbits/sec [ 4] 1.00-2.00 sec 128 KBytes 1.05 Mbits/sec [ 4] 2.00-3.00 sec 128 KBytes 1.05 Mbits/sec [ 4] 3.00-4.00 sec 128 KBytes 1.05 Mbits/sec [ 4] 4.00-5.00 sec 128 KBytes 1.05 Mbits/sec [ 4] 5.00-6.00 sec 128 KBytes 1.05 Mbits/sec [ 4] 6.00-7.00 sec 128 KBytes 1.05 Mbits/sec [ 4] 7.00-8.00 sec 128 KBytes 1.05 Mbits/sec [ 4] 8.00-9.00 sec 128 KBytes 1.05 Mbits/sec [ 4] 9.00-10.00 sec 128 KBytes 1.05 Mbits/sec

Test Complete. Summary Results: [ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams [ 4] 0.00-10.00 sec 1.26 MBytes 1.06 Mbits/sec 0.011 ms 0/161 (0%) [ 4] Sent 161 datagrams CPU Utilization: local/receiver 99.3%, remote/sender 14.4%

iperf Done.

I've gotten this in TCP mode too, when using a -b bandwidth throttle. UDP uses a throttle by default, so I'm guessing the problem is in the throttling/timer code, probably on the server side, and not UDP related. Will look into it.