Throughput Testing Guide¶

Overview¶

Throughput in WiFi refers to the amount of data transmitted from a source to destination within a specified period of time, usually measured in megabits per second (Mb/s). There are numerous factors that can affect throughput including the number of devices on the network, the protocol used (UDP vs TCP), and the host being used with the CC35xx. For example, using a Beaglebone Black (AM335) as a host will result in a lower throughput when compared to the AM62 being used as a host. This discrepancy in rates is due to the difference in how much data each device is capable of receiving. In order to get an accurate idea of the CC35xx throughput it is recommended that the test is conducted in a clean environment at first without interference for an accurate estimate of the device’s throughput capabilities with the desired host.

The main tool recommended to test the throughput of the CC35xx is known as iPerf and is an open source command line tool designed for testing network throughput. In order to use iPerf, at least one device must act as a server and another as a client. These devices should both be connected to the same AP and data will be transmitted between them with the AP acting as a bridge.

iPerf Introduction¶

In order for devices to be connected via iPerf, one needs to be configured as a server that is listening on the same port that the client will be configured to transmit to. The commands listed below can be used for various adjustments to this configuration. For example, to open a basic server configured for TCP broadcasts on the default port (5900) the following command would be used:

iperf -s

To open a basic client to transmit on the same port, also using TCP, the following command can be used:

iperf -c <server_ip_address>

To adjust the port, change the protocol to UDP, or other configurations the commands below can be used. This is not the full list, which can be displayed using iperf -h or iperf -help, but these are the commands most relevant to the throughput testing covered in this guide.

Client/Server:
-i, --interval          #       seconds between periodic bandwidth reports
-p, --port              #       server port to listen on/connect to
-u, --udp               #       use UDP rather than TCP
-w, --window            #       [KM]    TCP window size (socket buffer size)

Server specific:
-s, --server            #       run in server mode
-U, --single_udp        #       run in single threaded UDP mode

Client specific:
-b, --bandwidth         #       [KM] for UDP, bandwidth to send at in bits/sec (default 1 Mbit/sec, implies -u)
-c, --client            #       <host>   run in client mode, connecting to <host>
-n, --num               #       [KM] number of bytes to transmit (instead of -t)
-t, --time              #       time in seconds to transmit for (default 10 secs)

Miscellaneous:
-h, --help              #       print this message and quit

[KM] Indicates options that support a K or M suffix for kilo- or mega-

iPerf Throughput Example¶

Configuring the CC35xx as a client and the computer as a server.

In this configuration, the CC35xx is in station mode and connected to the AP via WiFi. Additionally, the computer behind the AP is connected through ethernet. A connection over ethernet, rather than WiFi, is recommended so that the computer behind the AP does not take up bandwidth and compete with the CC35xx over the air. The CC35xx is then configured using iPerf to be a client, while the computer is configured as a server. The data from the CC35xx is being transmitted from the CC35xx to the AP then to the computer. The steps to start this setup are as follows:

Connect the CC35xx to the AP as a station using the WiFi APIs.
Connect a computer or laptop (from here on out referred to as Computer 1) to the same AP via ethernet.

Run either ipconfig (Windows) or ifconfig (Linux) to find out the IP Address of the assigned to the computer. This is the IP address that the CC35xx will connect to with iPerf when configured as a client.

C:\Users\Administrator>ipconfig

Windows IP Configuration

Ethernet adapter AP:

    Connection-specific DNS Suffix  . : dhcp.ti.com
    Link-local IPv6 Address . . . . . : fe80::686b:36c3:ae90:e8de%29
    IPv4 Address. . . . . . . . . . . : 192.168.50.119
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Default Gateway . . . . . . . . . : 192.168.50.1

The IPv4 Address is the IP address assigned to the laptop by the AP while the Default Gateway is the IP Address of the AP itself.

3. To ensure that both Computer 1 and the CC35xx are properly connected it’s a good idea to ping Computer 1 from the CC35xx using the command below and it should produce a result similar to what is shown below if they are connected.

root@am335x-evm:/usr/share/cc35xx# ping 192.168.50.119
PING 192.168.50.119 (192.168.50.119): 56 data bytes
64 bytes from 192.168.50.119: seq=0 ttl=128 time=901.689 ms
64 bytes from 192.168.50.119: seq=1 ttl=128 time=105.525 ms
64 bytes from 192.168.50.119: seq=2 ttl=128 time=436.115 ms
64 bytes from 192.168.50.119: seq=3 ttl=128 time=561.868 ms

Open a server on Computer 1 with the following command:

iperf -s -p 5901 -i1

-s specifies that a server is being started
-p 5901 opens the server on port 5901
-i1 ensures that the data that is received by the server will be broadcasted on the screen
For more information, such as using UDP or adjusting the TCP window, reference the full list with the command iperf -h

Expected output on Computer 1:

C:\Users\Administrator>iperf -s -p 5901 -i1
------------------------------------------------------------
Server listening on TCP port 5901
TCP window size: 64.0 KByte (default)
------------------------------------------------------------

Connect to the server and transmit data from the CC35xx host using the following command:

iperf -c 192.168.50.119 -p 5901 -i1 -t5

-c specifies that a client is being started and will connect to the following IP address
-p specifies the same port that was opened on the server side
-i1 broadcasts the data which can be seen below on both the server and client sides
-t5 configures the device to transmit data for 5 sec

Expected output on CC35xx host:

root@am335x-evm:/usr/share/cc35xx# iperf -c 192.168.50.119 -p 5901 -i1 -t5
------------------------------------------------------------
Client connecting to 192.168.50.119, TCP port 5901
TCP window size: 83.8 KByte (default)
------------------------------------------------------------
[  3] local 192.168.50.143 port 35430 connected with 192.168.50.119 port 5901
[ ID] Interval       Transfer      Bandwidth
[  3]  0.0- 1.0 sec   XXX KBytes   Y.YY Mbits/sec
[  3]  1.0- 2.0 sec   XXX KBytes   Y.YY Mbits/sec
[  3]  2.0- 3.0 sec   XXX KBytes   Y.YY Mbits/sec
[  3]  3.0- 4.0 sec   XXX KBytes   Y.YY Mbits/sec
[  3]  4.0- 5.0 sec   XXX KBytes   Y.YY Mbits/sec

Expected output on Computer 1:

C:\Users\Administrator>iperf -s -p 5901
------------------------------------------------------------
Server listening on TCP port 5901
TCP window size: 64.0 KByte (default)
------------------------------------------------------------
[428] local 192.168.50.119 port 5901 connected with 192.168.50.119 port 5901
[ ID] Interval        Transfer      Bandwidth
[428]  0.0- 1.0 sec   X.XX MBytes   Y.YY Mbits/sec
[428]  1.0- 2.0 sec   X.XX MBytes   Y.YY Mbits/sec
[428]  2.0- 3.0 sec   X.XX MBytes   Y.YY Mbits/sec
[428]  3.0- 4.0 sec   X.XX MBytes   Y.YY Mbits/sec
[428]  4.0- 5.0 sec   X.XX MBytes   Y.YY Mbits/sec

Note

The above example can be adjusted based on the desired test in a number of ways. The configuration could be switched where the CC35xx host acted as the server and Computer 1 was the client by simply switching the same commands on the respective devices.