Is UDP connection capped at 1.05 Mbit/sec?

We tested transferring data to one of our servers via UDP and here is the result:

./iperf3 -c --udp Connecting to host, port 5201 [ 4] local port 52877 connected to port 5201 [ ID] Interval Transfer Bandwidth Total Datagrams [ 4] 0.00-1.00 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 1.00-2.01 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 2.01-3.00 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 3.00-4.00 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 4.00-5.00 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 5.00-6.00 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 6.00-7.00 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 7.00-8.00 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 8.00-9.00 sec 128 KBytes 1.05 Mbits/sec 16 [ 4] 9.00-10.00 sec 128 KBytes 1.05 Mbits/sec 16

[ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams [ 4] 0.00-10.00 sec 1.25 MBytes 1.05 Mbits/sec 59.160 ms 0/159 (0%)

Can someone help us make sense out of this? Same test done over TCP gives a speed of 170 Mbits/sec…


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Site Moderator
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March 10, 2023
Accepted Answer

Hey @cronchi,

That’s really strange, the only limits that should be exeprienced are here:

Can you see if you are still experiencing this? Is it possible the cap is also coming from your network? I’ll still ask around to see if there is any UDP cap.

The default

iperf3 -c hostname --udp

is only capped to 1Mbps

if you want to test with more bandwidth, add -b <bandwidth> argument to the command

iperf3 -c hostname --udp -b 100M

to test with 100Mbps Bandwidth

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