Iperf options


Iperf options

You can specify the following options when you run Iperf:


Runs Iperf locally in server mode. Iperf sits and listens for incoming connections.

-c hostname

Runs Iperf locally in client mode and attempts to initiate a connection with an existing Iperf server on the node specified by hostname. The value of hostname can be a name or an IP address.

-p port_number

Specifies the port that Iperf uses for communications. The default is port 5001.

-t time

Specifies the length in seconds for which to run Iperf testing. The defalut is 10 seconds. Specifying 30 seconds or longer generally gives more consistent results.


Runs tests using the UDP protocol. The default is the TCP protocol.

-b bandwidth[KM]

Specifies the bandwidth at which the client attempts to send when using the UDP protocol. To test the throughput of a UDP connection effectively, you should specify for the client to send at a higher throughput than you believe that the network has available. For example, if testing a 100 Mbps network connection, you should specify the bandwidth at higher than 100 M, such as 250 M. Failure to do this prevents the client from sending as fast as possible and gives an artificially low result for the available network bandwidth.

If you do not specify the -b option, Iperf defaults to 1 Mbps. Iperf does not want to try and flood the connection with UDP packets unless told to do so. However, you must flood the network to get a valid result. This option is not required when using the TCP protocol.

-l size

Specifies the size in bytes of datagrams to send during testing when using the UDP protocol. If not specified, Iperf defaults to 1470 byte datagrams to try and avoid packet fragmentation. This option is not required when using the TCP protocol.

-P number

Specifies the number of parallel connections to use when using the TCP protocol. If not specified, Iperf defaults to a single TCP connection. This can help simulate multiple TCP connections as used by Veritas Volume Replicator (VVR) in certain situations.

-B ip_address

Specifies a specific IP address to bind on the local node. This is useful where a machine has multiple IP addresses on the same subnet, as it can be used to bind Iperf to the same IP that would be used by VVR on each machine, ensuring that Iperf uses the same network infrastructure and routing as VVR traffic.

See Using Iperf to diagnose network issues

Terms of use for this information are found in Legal Notices.



Did this article answer your question or resolve your issue?


Did this article save you the trouble of contacting technical support?


How can we make this article more helpful?

Email Address (Optional)