Testing the available bandwidth between machines with Iperf

If we ever need a tool to measure bandwidths or to check an optimal configuration of our network or between delegations, we can use the Iperf utility that through a client-server connection can show us information of great interest!

Official Website: http://sourceforge.net/projects/iperf/

And if we need a Windows version (compiled with Cygwin) we can download it from AKI.

With 'iperf.exe -s’ It will start in server mode waiting for a client connection,

With 'iperf.exe -c DIRECCIÓN_IP -t120 -r’ We will be able to connect this client computer to the one running the iperf in server mode during 2 minutes of connection and monitor both outgoing and incoming traffic.

With the -f option we will change the output format to: Bit(b), bytes(B), Kilobits(k), Kilobytes(K), Megabits(m), Megabytes(M), Gigabit(g) or gigabytes(G).

With the -d option, you will generate bidirectional traffic simultaneously.

With -w we will send the TCP size (between 2 and 65,535 bytes).

With -p we will change the port, Default 5001.

With -i we will modify the interval so that it shows us the report.

With -u the tests will be with UDP.

With -b we will limit to a bandwidth.

With -m we will obtain the Maximum Segment Size (MSS), which is the largest amount of data that a computer/device supports in a single segment, Unfragmented. MSS = MTU – TCP header and IP header. TCP header and IP header = 40 bytes. Examples of MTU: Ethernet LAN:1500 bytes, PPPoE: 1492 bytes (ADSL), Ring Token or 16Mb/sec: 17914 bytes and dial-up: 576 bytes

For more information we will run the -h option

Usage: Iperf [-s|-C host] [options]
Iperf [-h|–help] [-v|–version]

Client/Server:

-f
-i
-l
-m
-p
-u
-w
-B
-C
-M
-N
-V

–format
–interval
–len
–print_mss
–port
–UDP
–window
–bind
–compatibility
–mss
–nodelay
–IPv6Version

[kmKM]
#
#[KM]

#

#[KM]
“host”

#

format to report: Kbits, Mbits, KBytes, MBytes
seconds between periodic bandwidth reports
length of buffer to read or write (default 8 KB)
print TCP maximum segment size (MTU – TCP/IP header)
server port to listen on/connect to
use UDP rather than TCP
TCP window size (socket buffer size)
bind to “host”, an interface or multicast address
for use with older versions does not sent extra msgs
set TCP maximum segment size (MTU – 40 bytes)
set TCP no delay, disabling Nagle’s Algorithm
Set the domain to IPv6

Server specific:

-s
-Or
-D

–Server
–single_udp
–daemon

run in server mode
run in single threaded UDP mode
run the server as a daemon

Client specific:

-b
-c
-d
-n
-r
-t
-F
-I
-L
-P
-T

–bandwidth
–client
–dualtest
–num
–tradeoff
–Time
–fileinput
–Stink
–listenport
–parallel
–ttl

#[KM]
“host”

#[KM]

#
“Name”

#
#
#

for UDP, bandwidth to send at in bits/sec (default 1 Mbit/sec, implies -u)
run in client mode, connecting to “host”
Do a bidirectional test simultaneously
number of bytes to transmit (instead of -t)
Do a bidirectional test individually
time in seconds to transmit for (default 10 secs)
input the data to be transmitted from a file
input the data to be transmitted from stdin
port to recieve bidirectional tests back on
number of parallel client threads to run
time-to-live, for multicast (default 1)

Miscellaneous:

-h
-v

–help
–version

print this message and quit
print version information and quit