There are plenty of tools out there to help you diagnose your network issues. Some of those tools are simple to use, and some of them require more education and time than you can afford to spend. Some of these tools are cheap, and some will require you to spend your entire IT budget. And then there is M-Lab. Not only is M-Lab free, it is easy to use and contains a number of effective tools to help diagnose your network.

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How does this work and why is it free? M-Lab is an open, distributed platform that allows developers and researchers to deploy their tools. So as a developer or researcher, it is a way to offer your tools for public consumption. To learn more about how to add your tools to the M-Lab site, read the researcher documentation.

As a user not only will you be able to gain important information about your network, you will also be helping M-Lab by providing valuable data that will further network research.

The tools

The tools included with M-Lap are:

  • Network Diagnostic Tool: This tool will test connection speeds and diagnose speed-limiting issues.
  • Glasnost: Check to see if BitTorrent is being blocked on your network.
  • Network Path and Application Diagnosis: Diagnose common last-mail issues that plague broadband.
  • Pathload2: Test available bandwidth.

Two other tools are under development, but they are not quite ready yet. Let’s take a close look at each tool.

Network Diagnostic Tool

Network Diagnostic Tool: At first look, you might think this tool does only one thing — record upload and download speeds of your network. However, it does more than that. While checking speeds, NDT attempts to determine what, if any, issues are limiting speeds.

NDT attempts to determine:

  • The slowest link in the point-to-point path
  • The Ethernet duplex setting
  • Congestion that is limiting point-to-point throughput
  • Duplex mismatch
  • Excessive packet loss due to faulty cable

This test will take less than 30 seconds to run.

Note: NDT uses a queuing process to determine what is next in line for testing.

To run a test, click on the server nearest your location. When the new page appears and your test is ready to run, click the Start button to begin your test. When running this test I had to tell Windows Firewall to unblock traffic in order to complete it.

When the test completes, the results will be displayed in your browser (Figure A).

Figure A

The results are short and sweet but informative.

As you can see in the test results, there is other traffic congesting my connection as well as packet queuing. As I am connected to a business DSL line, traffic on the network is slow. The only reason that would keep me from calling my provider at this point is that the test sends out 10 seconds’ worth of traffic and the network I am connected to might not be able to keep up with that data just at that particular time. So retesting at another time and comparing the results would be in order before placing a call.


Glasnost: Glasnost attempts to determine if your provider is doing some sort of traffic shaping. At the current release, Glasnost can check only for BitTorrent blocking, but the developers have already indicated tests for other applications will follow soon.

To run the Glasnot test, click on the link for the test (which will take you away from the M-Labs site), scroll down, select the type of test, and click the Start Testing button. There are two different tests: simple and detailed. The simple test takes only four minutes where the detailed test takes seven.

The Glasnost test will attempt to deliver packages to standard BitTorrent ports. Ports tested are 6881 and 10009. The test results will also check seeding of BitTorrent and report the Kbps achieved. Figure B illustrates a successful check for open BitTorrent ports. These results indicate that packet shaping is not occurring.

Figure B

All BitTorrent ports are wide open on my network.

Network Path and Application Diagnosis

Network Path and Application Diagnosis: This test examines typical issues surrounding the last mile of a connection to your location. To run this test, click on the link and then choose the location nearest you. For this test you need to have an end-to-end performance goal and target data range in mind. By default these values are 20ms for the Round Trip Time (end-to-end performance goal) and 10Mbs for the target data range. These values should suffice unless you have specific needs. Once you enter these values click the Start Test button. As your results come in, they will scroll by in the text area. This test should take anywhere from 2 to 5 minutes.
As you can see in Figure C, the data rate test failed. What this tells me is that I am not getting the speeds I should be getting for my network. Of course, the test results do not show a rate that is below my expectations. Although the network promises 10Mbs speed, 6Mbs is acceptable for this location.

Figure C

Not only did the data rate test fail, but there was a warning of a time-stamp issue on the client side.


Pathload2: This test will examine the available bandwidth of your connection. Available bandwidth is the amount of data you can send or receive before your network gets congested. To run this test, click on the link above and then download the client for your operating system. Once it is downloaded, click on the executable file to open the client for testing. Now click on the Start New Measurement button, and the test will begin. You will have to tell the Windows Firewall to allow the traffic to get through so the test can take place.
The test will take only a couple of minutes to complete, and once finished, your results will appear in the client window (Figure D).

Figure D

The results are in: .45 Mbps upstream and 4.75 Mbps downstream.

Granted the results of this test can vary and will be directly affected by traffic on your network. So it is best to take this test multiple times and average the results to get a clear picture.

Final thoughts

The testing tools at M-Lab are easy to use, are free, and offer a good look into the speeds of your network. Granted they are not going to help you to determine if there is a problem from the inside-out, but from the outside-in, these tools can be of real value.

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