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Invoking iperf3
===============
iperf3 includes a manual page listing all of the command-line options.
The manual page is the most up-to-date reference to the various flags and parameters.
For sample command line usage, see:
http://fasterdata.es.net/performance-testing/network-troubleshooting-tools/iperf-and-iperf3/
Using the default options, iperf3 is meant to show typical well
designed application performance. "Typical well designed application"
means avoiding artificial enhancements that work only for testing
(such as ``splice()``-ing the data to ``/dev/null``). iperf3 does
also have flags for "extreme best case" optimizations but they must be
explicitly activated. These flags include the ``-Z`` (``--zerocopy``)
and ``-A`` (``--affinity``) options.
iperf3 Manual Page
------------------
This section contains a plaintext rendering of the iperf3 manual page.
It is presented here only for convenience; the authoritative iperf3
manual page is included in the source tree and installed along with
the executable.
::
IPERF3(1) User Manuals IPERF3(1)
NAME
iperf3 - perform network throughput tests
SYNOPSIS
iperf3 -s [ options ]
iperf3 -c server [ options ]
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.
GENERAL OPTIONS
-p, --port n
set server port to listen on/connect to to n (default 5201)
-f, --format
[kmKM] format to report: Kbits, Mbits, KBytes, MBytes
-i, --interval n
pause n seconds between periodic bandwidth reports; default is
1, use 0 to disable
-F, --file name
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
-A, --affinity n/n,m
Set the CPU affinity, if possible (Linux and FreeBSD only). On
both the client and server you can set the local affinity by
using the n form of this argument (where n is a CPU number). In
addition, on the client side you can override the server's
affinity for just that one test, using the n,m form of argument.
Note that when using this feature, a process will only be bound
to a single CPU (as opposed to a set containing potentialy mul-
tiple CPUs).
-B, --bind host
bind to a specific interface
-V, --verbose
give more detailed output
-J, --json
output in JSON format
--logfile file
send output to a log file.
--forceflush
force flushing output at every interval. Used to avoid buffer-
ing when sending output to pipe.
-d, --debug
emit debugging output. Primarily (perhaps exclusively) of use
to developers.
-v, --version
show version information and quit
-h, --help
show a help synopsis
SERVER SPECIFIC OPTIONS
-s, --server
run in server mode
-D, --daemon
run the server in background as a daemon
-I, --pidfile file
write a file with the process ID, most useful when running as a
daemon.
-1, --one-off
handle one client connection, then exit.
CLIENT SPECIFIC OPTIONS
-c, --client host
run in client mode, connecting to the specified server
--sctp use SCTP rather than TCP (FreeBSD and Linux)
-u, --udp
use UDP rather than TCP
-b, --bandwidth n[KM]
set target bandwidth to n 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). On platforms supporting the SO_MAX_PACING_RATE socket
option (currently only Linux), fair-queueing socket-level pac-
ing, implemented in the kernel, will be used. On other plat-
forms, iperf3 will implement its own rate control.
--no-fq-socket-pacing
disable the use of fair-queueing based socket-level pacing with
the -b option, and rely on iperf3's internal rate control.
-t, --time n
time in seconds to transmit for (default 10 secs)
-n, --bytes n[KM]
number of bytes to transmit (instead of -t)
-k, --blockcount n[KM]
number of blocks (packets) to transmit (instead of -t or -n)
-l, --length n[KM]
length of buffer to read or write (default 128 KB for TCP, 8KB
for UDP)
--cport port
bind data streams to a specific client port (for TCP and UDP
only, default is to use an ephemeral port)
-P, --parallel n
number of parallel client streams to run
-R, --reverse
run in reverse mode (server sends, client receives)
-w, --window n[KM]
window size / socket buffer size (this gets sent to the server
and used on that side too)
-M, --set-mss n
set TCP/SCTP maximum segment size (MTU - 40 bytes)
-N, --no-delay
set TCP/SCTP no delay, disabling Nagle's Algorithm
-4, --version4
only use IPv4
-6, --version6
only use IPv6
-S, --tos n
set the IP 'type of service'
-L, --flowlabel n
set the IPv6 flow label (currently only supported on Linux)
-X, --xbind name
Bind SCTP associations to a specific subset of links using
sctp_bindx(3). The --B flag will be ignored if this flag is
specified. Normally SCTP will include the protocol addresses of
all active links on the local host when setting up an associa-
tion. Specifying at least one --X name will disable this behav-
iour. This flag must be specified for each link to be included
in the association, and is supported for both iperf servers and
clients (the latter are supported by passing the first --X argu-
ment to bind(2)). Hostnames are accepted as arguments and are
resolved using getaddrinfo(3). If the --4 or --6 flags are
specified, names which do not resolve to addresses within the
specified protocol family will be ignored.
--nstreams n
Set number of SCTP streams.
-Z, --zerocopy
Use a "zero copy" method of sending data, such as sendfile(2),
instead of the usual write(2).
-O, --omit n
Omit the first n seconds of the test, to skip past the TCP slow-
start period.
-T, --title str
Prefix every output line with this string.
-C, --congestion algo
Set the congestion control algorithm (Linux and FreeBSD only).
An older --linux-congestion synonym for this flag is accepted
but is deprecated.
--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
--json flag, the output will be in JSON format, otherwise it
will be in human-readable format). If the client is run with
--json, the server output is included in a JSON object; other-
wise it is appended at the bottom of the human-readable output.
AUTHORS
A list of the contributors to iperf3 can be found within the documenta-
tion located at http://software.es.net/iperf/dev.html#authors.
SEE ALSO
libiperf(3), http://software.es.net/iperf
ESnet May 2016 IPERF3(1)
The iperf3 manual page will typically be installed in manual
section 1.
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