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How to Test if Your ISP is Throttling Your Internet Connection

ethernet-cables

We’ve all heard the rumors and seen occasional evidence — some Internet service providers slow down certain types of traffic, like BitTorrent traffic. Other ISPs slow down their customers’ connections if they download too much data in a month.

But does your ISP do any of this? Here are a few simple ways you can test whether your ISP is performing any traffic shaping or bandwidth throttling on your connection.

Traffic Shaping

The Glasnost project provides web-based tests that can identify whether different types of traffic are being rate-limited (slowed down). For example, run the BitTorrent test and Glasnost will test whether your ISP is slowing down your BitTorrent transfers. Glasnost can also run tests to detect whether Flash video, eMule, Gnutella, Email, HTTP, SSH, or Usenet are being throttled or blocked by your ISP. Each test takes about eight minutes to run.

Glasnost measures the performance of different types of traffic between your computer and their servers. If the speeds are similar, no traffic shaping is likely occurring. If the speeds are different — for example, if BitTorrent traffic is much slower — then traffic-shaping is likely occurring.

glastnost-results

Unfortunately, the Glasnost tests require you have the Java plug-in installed. If you want to run these tests, we recommend you uninstall Java or at least disable the Java plug-in immediately after — the Java plug-in has been a big source of security problems. You should also watch out for the terrible Ask Toolbar and make sure not to install it while installing Java. We normally wouldn’t recommend using websites that require Java, but the Glasnost tests are the most widely recommended tests you can use.

As with other similar tests, you’ll want to run Glasnost tests while you’re not performing any large downloads on your network.

Bandwidth Limiting

Is your ISP slowing down your connection because you’ve used too much data? Some ISPs have been known to do this as a way of enforcing their bandwidth caps. Even ISPs that offer “unlimited” connections may throttle you after you hit a certain, usually large, threshold.

To test whether your ISP is slowing down your Internet connection over time, you’ll have to measure your Internet connection speed over time. For example, if your ISP is slowing your Internet speed down, it’s probably slowing it down towards the end of the month after you’ve used a large amount of data. You then probably have typical, fast speeds at the beginning of the next month.

You can monitor Internet speed variations over time by using the SpeedTest website. Run a test at the beginning of the month and run further tests regularly, especially at the end of the month. If you consistently see slower speeds near the end of the month, it’s possible that your ISP is throttling your bandwidth. You can sign up for a SpeedTest account to log your results and compare them over time.

speedtest

Note that other factors can also affect SpeedTest results. For example, if you or any other person on your network is downloading or uploading on your connection, the measurement may not be accurate — you should perform a SpeedTest while your connection isn’t being used. The time of day can also impact your Internet connection speeds. You may see faster speeds at 3 a.m. when no one is using the shared line to your ISP rather than at 9 p.m. while everyone else in your neighborhood is using the line.

It’s also normal if you don’t see the maximum speeds your ISP is advertising — most people aren’t getting the Internet speeds they’re paying for.

Other Tools

The Measurement Lab (M-Lab) provides a variety of other tools that can be used to measure Internet connection data, testing for traffic shaping, measuring network performance, and diagnosing network problems. If you’re looking for other tools to test your connection, this is a good place to start.

m-lab-internet-connection-testing-tools


If your ISP is throttling your connection, there’s not much you can do, unfortunately. You can switch ISPs and try to find a better one — assuming your ISP doesn’t have a monopoly in your area. You may also be able to pay for a more expensive plan with higher bandwidth allocation and, hopefully, without traffic shaping.

Image Credit: Jerry John on Flickr

Chris Hoffman is a technology writer and all-around computer geek. He's as at home using the Linux terminal as he is digging into the Windows registry. Connect with him on Google+.

  • Published 06/17/13

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