Network Performance test Tool Iperf Introduction

"Summary"Iperf is a network performance testing tool, it can be easily used for SDN network bandwidth and network quality testing,Iperf Support protocol, timing, Configuration adjustment of buffers and other parameters, reporting tcp/udp Maximum bandwidth, delay jitter, packet loss and other statistics.

1 Iperf Installation

Iperf Installation method has a variety, you can download the source code compiled installation, you can also directly use the compiled binary version, installed in ubuntu using Iperf is particularly simple, apt-get Install Iperf , it is worth mentioning that mininet comes with Iperf , in SDN the test on the network is relatively convenient.

2 Working principle

When you use the Iperf test, you must set up a host as a client and a host to the server.

Iperf testing TCP

Iperf The principle of testing TCP bandwidth is relatively simple, after the client and the server to establish three handshake connection, the size of the client bandwidth is equal to the total amount of data sent divided by the total time sent. The bandwidth measured on the server is the total data received divided by the time spent.

A simple example of TCP mode:

Server:iperf-s

Client:iperf-c 10.0.0.1-i 1

The bandwidth test on the client-to-server 10.0.0.1 , printing information once every second.

Iperf testing UDP

Iperf when testing UDP performance, clients can specify The rate of UDP traffic. When the client sends data, the delay between datagrams is calculated based on the rate provided by the client.

The client can also specify the size of the sending datagram. Each datagram is sent with an ID number that uniquely identifies the message and the server side determines the datagram loss and chaos based on that ID number.

When the UDP message size is set to put the entire message into the packet (packet) of the IP layer , then the UDP The measured packet loss data is IP Packet loss data, which provides a way to test packet loss in a valid manner.

The data datagram transmission delay jitter (jitter) test is done by the server side, the customer sends the message data contains the sending timestamp, the server side calculates the transmission delay jitter based on the time information and the timestamp of the received message. Transmission delay jitter reflects the smoothness of the transfer process. Because it is a relative value, there is no need for client and server-side time synchronization.

A simple example of UDP mode:

Server:iperf-s-u

Client:iperf-c 10.0.0.1-u-B 100M

In UDP mode, the client tests the bandwidth on the client-to-server 10.0.0.1 at 100Mbps for the data send rate .

In summary, the quality of the network connection is tested in the following ways:

- delay (reaction time or RTT): Measured with the ping command

-Jitter(delay change): Measured with Iperf UDP test

-Datagram loss: measured with Iperf UDP test

- bandwidth: measured by TCP test

3 parameter configuration

Table 1. Client / server-side common parameters

Table 2. server-side parameters

Table 3. Client Parameters

4 Test examples

Test environment

1) built a set of SDN network environment, using mininet analog switch and host to connect to a OpenFlow Controller.

2) Use mininet 's own Iperf tool

Application examples

Example one: The simplest parameter instance

Iperf Client connects to the TCP default port of Iperf server 5001, otherwise we can use - p parameter modifies the port of the Iperf server, and the client and server must add the same port. The results show that the bandwidth is the bandwidth from the user to the server.

Example two: bidirectional bandwidth testing

the-R parameter measures bidirectional bandwidth, and theIperf Server proactively initiates a connection to the client.

Example three: synchronous bidirectional bandwidth Testing

The bidirectional bandwidth is measured synchronously using the-D parameter, while the- R in the previous example only measures the client-to-server bandwidth when it is in its initial state.

Example four:TCP window size

In connection, if the receiver is too late to verify, the data is temporarily in a buffer, the upper limit of the buffer is the so-called TCP window size, the window size can be 2 to 65,535 between the bytes.

Example five:UDP test

The UDP test gets important information about jitter and packet loss.

Good connection quality, packet loss rate is less than 1%, packet loss rate is too high will cause many TCP datagrams need retransmission, thereby affecting the bandwidth. jitter represents a delay change, not dependent on the delay itself, you may have a long reaction time, but the jitter is very low.

5 Concluding remarks

Jperf with Iperf can provide a java written graphical interface, you can learn by themselves, here do not introduce. If there are deficiencies please dabigatran discuss , thank you.

This article is from Sdnlab, click here to read the original . If you are interested in this article, you can participate in the following interactive ways to communicate with the author in close range.

(1) Weibo ( http://weibo.com/sdnlab/ )

2) ( account No. : Sdnlab)

(3) QQ Group

SD N Research Group (214146842)

Opendaylight Research Group (194240432)

Network Performance test Tool Iperf Introduction