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Testing Data Transfer Rates on a Mesh

Author: Terry Gillett

To get some benchmarks around what is possible in terms of data transfer rates across a SECN-1 mesh link, I have done some testing with various devices including the MP01, MP02, and TP Link devices including WR703N and WDR4300.

The idea is to develop simple end-to-end data transfer tests that can be applied to mesh network links in the field to check that they are operating at least reasonably well compared to 'best case' benchmarks. The tests also illustrate the practical limitations of what can be expected in terms of performance of real world networks used for typical data transfer applications.


Test set Up

My test set up is two laptop PCs running Ubuntu, with each laptop connected to a mesh node device via Ethernet.

The laptops are configured with static IP addresses.

As a baseline, I also tested with the two laptops directly connected by Ethernet cable.

To run the test, I transfer a file of several hundred MBytes (eg an iso file for an Ubuntu image) from the /tmp directory on one laptop to the /tmp directory on the other laptop using the 'scp' command as follows:

    $ scp /tmp/testfile   [email protected]:/tmp

Where 192.168.1.100 is the IP address of the destination laptop.

The scp command will request the password for 'myuser' on the destination machine then transfer the file, displaying some statistics.

The test can be repeated as required without having to manipulate any files at either end.

The data transfer rate may be measured using the Ubuntu graphical System Monitor application, and also the statistics that the 'scp' command displays. The results of both these measurements should be the same.

Note that the 'scp' command statistics are shown in MBytes per sec, whereas the System Monitor application can be configured to display in either MBytes per sec (MBps - default) or Mbits per sec (Mbps).

The ratio between these is about 1:10.

Wifi devices are usually rated in Mbits per sec (Mbps) e.g 802.11g nominally supports up to 54Mbps.


Initial Tests

For the initial tests, I had the mesh node devices placed at a distance of 10 metres and running the default configuration 'as-flashed'. Default TX Power settings are 17dBm for 2.4GHz and 14dBm for 5GHz devices.


The results of these tests were as follows:

Direct Ethernet connection
200 Mbits per sec. Consistent.


Mesh Potato MP01
MP01: 20 Mbps best case. Variable, sometimes dropping to 5 Mbps


TP Link WR703N
TP Link WR703N: 40 Mbps. Consistent.


TP Link WDR4300 with 2.4GHz radio only
TP Link WDR4300 with 2.4GHz radio only: 40 Mbps. Consistent


TP Link WDR4300 with 5GHz radio only
TP Link WDR4300 with 5GHz radio: 100 Mbps best case. Variable, sometimes dropping to 75 Mbps


TP Link WDR4300 with both 2.4GHz and 5Ghz radios operating, and both meshes bridged to brlan
TP Link WDR4300 with both 2.4GHz and 5Ghz: 120 Mbps best case. Variable, sometimes dropping to 75 Mbps


MP2 Tests

the basic test set up is comprised of three MP2 devices (Nodes-A, B and C) set out in a straight line, so that the distance A-C is about double that for A-B and B-C.


Test 1. Single Mesh Hop

In this test, Node-A and Node-C are meshed via a single high quality link, with a SNR of 40dB and batman-adv score of 255 as can be seen in the Test-1 screenshots of the Status page of each node.

The transfer rate is up to 30Mbps as can be seen from the Test-1 iftop screenshots.

This test represents a realistic best case scenario for a mesh link using the MP2 devices.

If the link quality decreases for any reason (eg lower SNR, or wifi interference), you can expect that the data rate will be less.


Node A iftop screen
Node A Status screen
Node C iftop screen
Node C Status screen


Test 2. Two Mesh Hops

In this test, the data transfer occurs via two mesh hops, A to B and B to C, with reduced SNR and batman-adv scores for the links, as can be seen from the Test-2 Status screenshots.

The link quality can be adjusted by reducing the TxPower (for all nodes equally) and by extending the distance between nodes.

The end to end data transfer rate for this test is around 10Mbps as can be seen from the Test-2 iftop screenshots.

In the Status screen for Node-B you can see the status of the two active links A-B and B-C.

The Signal Strength section of the Status page also shows the SNR for the link and the number of data packets transferred across the link.

It is worth checking the packet count on each link just to be certain that the data is actually flowing through the link that you expect it to i.e. A-B-C and not A-C.

Looking at the packet counts on the Status pages for Node-A and Node-C should show that one link is carrying the data (A-B or B-C) and the other link (A-C) is idle.

Of course, if the A-C link is of sufficient quality, data may flow through this single hop rather than via the two hops.

As a variation on this test, you can move the laptop from Node-C to Node-B and measure the data rate, which will typically be double that for the end-to-end data rate across two links. This is because the MP2 is a single radio device and each additional mesh hop will reduce the throughput by a factor of two.


Node A iftop screen
Node A Status screen
Node B iftop screen
Node B Status screen
Node C iftop screen
Node C Status screen


Test 3. WiFi Link

Test 3 has a laptop connected by Ethernet to the LAN port of the MP2, and a second laptop connected via wifi to the AP on the MP2.

The wifi connected laptop initiates a scp transfer. The iftop screenshot shows the data rate on wlan0, the AP interface on the MP2.

The System Monitor screenshot shows the network data rate on the second laptop as it is receiving the file.

The data rate is just under 30MBps.


Wifi Interface iftop screenshot
System Monitor screenshot


Test 4. Mesh Link and WiFi Link

Test 4 has two MP2s meshed together, with the first laptop connected to one MP2 via Ethernet, and the second laptop is connected to the second MP2 via wifi.

The second laptop initiates a scp transfer, so the data flows from the first laptop to the first MP2, then across the mesh to the second MP2, then across the wifi link to the second laptop.

The iftop screenshots show the data rate for the bat0 Mesh interface on the first MP2, and the data rate for the wlan0 AP interface on the second MP2.

The System Monitor screenshot shows the network data rate on the second laptop as it is receiving the file.

The end-to-end data rate is around 15Mbps.

These tests were conducted with SNR values of 30 on the Mesh and AP links, and so represent a best case scenario.

Wifi Interface iftop screenshot
Mesh Interface iftop screenshot
System Monitor screenshot


Further Tests

If you are able to undertake similar tests, please post the results on the Village Telco google group.