iPerf3 UDP Test Guide: Throughput, Loss & Jitter

Start with a UDP test

UDP testing lets you specify an offered sending rate and examine the receiver’s bitrate, loss, and jitter. The -u switch selects UDP, and -b sets a target bitrate per stream.

100 Mbps UDP test

iperf3 -c 192.0.2.10 -p 5201 -u -b 100M -t 30 -i 1 -f m

Replace the example address with your intended iPerf3 server. The client establishes a TCP control connection even when UDP is selected for test traffic.

UDP options explained

Option	Purpose
`-u`	Send UDP test traffic instead of TCP.
`-b 100M`	Target 100 Mbit/s for each stream.
`-b 0`	Remove iPerf3’s UDP sending-rate limit.
`-t 30`	Run the test for 30 seconds.
`-i 1`	Report results at one-second intervals.
`-f m`	Display bitrates in Mbits/sec.
`-P 4`	Use four parallel streams; the target bitrate applies to each stream.

Unlimited UDP and parallel streams

By default, iPerf3 uses a UDP target of 1 Mbit/s when no -b is supplied. Use -b 0 to remove that configured limit.

Unlimited UDP sending-rate target

iperf3 -c 192.0.2.10 -u -b 0 -t 10 -f m

Parallel streams are optional. A single-stream UDP test needs no -P flag. If you use -P 4 -b 100M, the configured aggregate target is 400 Mbit/s in the selected sending direction, not 100 Mbit/s total.

Reading the result: Sender bitrate represents transmitted traffic; receiver bitrate, loss, and jitter describe what the receiving endpoint reports. When evaluating delivered traffic, compare both sides rather than treating the requested send rate as the achieved receive rate.

Jitter and packet loss

UDP summaries can report jitter (in milliseconds) and lost versus total datagrams at the receiving endpoint. Higher offered loads can produce increased loss or jitter, so changing -b allows targeted tests at different rates. Public servers may limit supported rates or concurrent tests.