.TH IPERF 1 "June 2014" ESnet "User Manuals"
.SH NAME
iperf3 \- perform network throughput tests
.SH SYNOPSIS
.B iperf3 -s [
.I options
.B ]
.br
.B iperf3 -c 
.I server
.B [
.I options
.B ]

.SH DESCRIPTION
iperf3 is a tool for performing network throughput measurements.  It can test
either TCP or UDP throughput.  To perform an iperf3 test the user must
establish both a server and a client.

.SH "GENERAL OPTIONS"
.TP
.BR -p ", " --port " \fIn\fR"
set server port to listen on/connect to to \fIn\fR (default 5201)
.TP
.BR -f ", " --format " "
[kmKM]   format to report: Kbits, Mbits, KBytes, MBytes
.TP
.BR -i ", " --interval " \fIn\fR"
pause \fIn\fR seconds between periodic bandwidth reports;
default is 1, use 0 to disable
.TP
.BR -F ", " --file " \fIname\fR"
client-side: read from the file and write to the network, instead
of using random data;
server-side: read from the network and write to the file, instead
of throwing the data away
.TP
.BR -A ", " --affinity " \fIn/n,m\fR"
Set the CPU affinity, if possible (linux only).
On both the client and server you can set the local affinity;
in addition, on the client side you can override the server's
affinity for just that one test, using the n,m form.
.TP
.BR -V ", " --verbose " "
give more detailed output 
.TP
.BR -J ", " --json " "
output in JSON format
.TP
.BR -d ", " --debug " "
emit debugging output.
Primarily (perhaps exclusively) of use to developers.
.TP
.BR -v ", " --version " "
show version information and quit
.TP
.BR -h ", " --help " "
show a help synopsis

.SH "SERVER SPECIFIC OPTIONS"
.TP
.BR -s ", " --server " "
run in server mode
.TP
.BR -D ", " --daemon " "
run the server in background as a daemon

.SH "CLIENT SPECIFIC OPTIONS"
.TP
.BR -c ", " --client " \fIhost\fR"
run in client mode, connecting to the specified server
.TP
.BR -u ", " --udp
use UDP rather than TCP
.TP
.BR -b ", " --bandwidth " \fIn\fR[KM]"
set target bandwidth to \fIn\fR bits/sec (default 1 Mbit/sec for UDP, unlimited for TCP).
If there are multiple streams (\-P flag), the bandwidth limit is applied
separately to each stream.
You can also add a '/' and a number to the bandwidth specifier.
This is called "burst mode".
It will send the given number of packets without pausing, even if that
temporarily exceeds the specified bandwidth limit.
Setting the target bandwidth to 0 will disable bandwidth limits
(particularly useful for UDP tests).
.TP
.BR -t ", " --time " \fIn\fR"
time in seconds to transmit for (default 10 secs)
.TP
.BR -n ", " --bytes " \fIn\fR[KM]"
number of bytes to transmit (instead of \-t)
.TP
.BR -k ", " --blockcount " \fIn\fR[KM]"
number of blocks (packets) to transmit (instead of \-t or \-n)
.TP
.BR -l ", " --length " \fIn\fR[KM]"
length of buffer to read or write (default 128 KB for TCP, 8KB for UDP)
.TP
.BR -P ", " --parallel " \fIn\fR"
number of parallel client streams to run
.TP
.BR -R ", " --reverse
run in reverse mode (server sends, client receives)
.TP
.BR -w ", " --window " \fIn\fR[KM]"
TCP window size / socket buffer size (this gets sent to the server and used on that side too)
.TP
.BR -B ", " --bind " \fIn\fR[KM]"
bind to a specific interface or multicast address
.TP
.BR -M ", " --set-mss " \fIn\fR"
set TCP maximum segment size (MTU - 40 bytes)
.TP
.BR -N ", " --no-delay " "
set TCP no delay, disabling Nagle's Algorithm
.TP
.BR -4 ", " --version4 " "
only use IPv4
.TP
.BR -6 ", " --version6 " "
only use IPv6
.TP
.BR -S ", " --tos " \fIn\fR"
set the IP 'type of service'
.TP
.BR -L ", " --flowlabel " \fIn\fR"
set the IPv6 flow label (currently only supported on Linux)
.TP
.BR -Z ", " --zerocopy " "
Use a "zero copy" method of sending data, such as sendfile(2),
instead of the usual write(2).
.TP
.BR -O ", " --omit " \fIn\fR"
Omit the first n seconds of the test, to skip past the TCP slow-start
period.
.TP
.BR -T ", " --title " \fIstr\fR"
Prefix every output line with this string.
.TP
.BR -C ", " --linux-congestion " \fIalgo\fR"
Set the congestion control algorithm (linux only).
.TP
.BR "--get-server-output"
Get the output from the server.
The output format is determined by the server (in particular, if the
server was invoked with the \fB--json\fR flag, the output will be in
JSON format, otherwise it will be in human-readable format).
If the client is run with \fB--json\fR, the server output is included
in a JSON object; otherwise it is appended at the bottom of the
human-readable output.

.SH AUTHORS
Iperf was originally written by Mark Gates and Alex Warshavsky.
Man page and maintence by Jon Dugan <jdugan at x1024 dot net>.
Other contributions from Ajay Tirumala, Jim Ferguson,
Feng Qin,
Kevin Gibbs,
John Estabrook <jestabro at ncsa.uiuc.edu>,
Andrew Gallatin <gallatin at gmail.com>,
Stephen Hemminger <shemminger at linux-foundation.org>

.SH "SEE ALSO"
libiperf(3),
http://software.es.net/iperf