Visual proof Comcast throttles my cable connection!

I saw an article on Digg today about how Comcast is denying rumors that they are throttling BitTorrent traffic. I have my own proof that they are! In the following experiment I used Speakeasy's Speed Test for the speed results.

I've measured my connection speed several times over the past few weeks, so I have a pretty good idea what kind of speeds I should be getting when my connection is idle. Usually I get around 18000 kbps down and 1600 kbps up. For the sake of this experiment, I'll run the test once before I try downloading a torrent:

Speakeasy Speed Test 3

Speakeasy Speed Test 4

OK, the results look normal (fast for $55 a month!). I then browsed to my favorite torrent site, mininova.org, and downloaded a totally legal 50mb torrent using the open-source BitTorrent client Azureus (v2.5.0.4). The download took about 4 minutes.

Downloading a Torrent

After the download finished, I exited Azureus to make sure nothing was seeding, waited 5 minutes, and than ran Speakeasy's Speed Test again:

Speakeasy Speed Test 1

Speakeasy Speed Test 2

Wow, why so slow?! My first thought was that maybe there were a lot of people in my neighborhood downloading stuff through their Comcast connection, but then I remembered that was 2001. Comcast has upgraded their network since then, so I should be getting blazing speeds! Besides, it was only 10 minutes ago that I was getting 4x the download speed and over 25x the upload speed!

I waited another 20 minutes and tried the speed test again. This time the results came back normal (same speed as the first test). To confirm this wasn't just a coincidence, I repeated this experiment half a dozen times. Every single time, my connection speed slowed down considerably after about 4 - 5 minutes of downloading a torrent and returned to normal within 20 - 25 minutes of no BitTorrent traffic.

If Comcast thinks they can get away with throttling BitTorrent traffic, then it won't be long before they start throttling other traffic and even charging extra for it. How many YouTube video's have you watched? Oh, thats an additional $6 on your bill this month.

Write a Comment

Comment

18 Comments

  1. To ensure your router/gateway is not the problem, can you repeat this test by connecting the WAN cable directly to your computer, reboot both your Broadband modem and computer, verify that you are connected to the Internet, and then repeat the steps you took before?

    If that is too inconvenient, then at least do this:
    1. Shut down your torrent application after the torrent finishes
    2. Reboot your router to clear memory (remove power, wait a few secs, restore power)
    3. Repeat your speed test immediately
    4. Repeat it again 20-25 minutes later (as you did before)

    I’m also concerned whether or not “PowerBoost” is showing up in these test results. What is your purchased speed? Are your best test results significantly over your purchased speed?

  2. Hello Robb,

    My purchased speed is 8 Mbps/768 Kbps, so obviously I’m getting a lot faster upload speeds than I should be, however the download speed is still cut in half after I’ve downloaded a torrent. It’s definitely possible that PowerBoost is kicking in during my tests, however the main point of the results was that my connection speed is being throttled after transmitting BitTorrent traffic.

    I’ll rerun the experiment tonight using both methods you mentioned above and post my results here.

  3. I connected my cable modem directly to the computer, rebooted everything, then repeated the above experiment: Same results.

    Then I followed the steps Robb listed above. When I tested the speed in step 3, it was considerably slower. But after waiting 20-25 minutes the speed returned to normal.

  4. I personally dont trust speakeasy i have always had kinda strange and wierd results from them. Personally i prefer to use speedtest.net i seem to get more reliable results. But Comcast is certainly throttling bandwith and not just on torrents. In fact i am pretty sure if you do any kind of downloading it trips a flag with them and you are automatically throttled. I once had a conversation with there “tech support” and was pretty much told that anyone who is a high bandwith user will be monitored and liable to limitations at there discretion. Say hi to big brother for me!!!

  5. Hey Paul,

    Thanks for the info that Speakeasy’s speed test might being giving inaccurate results. I used to use several different broadband speed test sites, but I guess the clean and simple nature of Speakeasy’s speed test made me forget the others even existed! Certainly though, for an experiment such as this, I should have taken my speed results from several different sources. This experiment was done “on the fly” and my decision to post my results on my blog was an afterthought.

    If I had more free time, I would love to conduct more tests, but I think the fact that Comcast throttles bandwidth has pretty much been proven by the large response on the Internet from other Comcast users who have had similar experiences.

    I placed my order with Speakeasy today to switch to their OneLink service, with a 1.5Mbps down and 384k up line speed, for $55 a month — the same as I’m paying right now for my Comcast connection. I just really hate feeling like I can’t leave my computer downloading a big file overnight without raising eyebrows at Comcast. And besides, why should I support them by paying for their service when I can support another company who believes in more open values.

  6. I loathe comcast but where I live, it’s the only option for ‘good’ internet that is offered in our area. I often experience very slow download/upload speeds and the customer service is useless.

    What a greedy horrible company. I can’t wait for fios or some other broadband alternative to come take over Denver broadband. Everyone is sick of the monopoly that they have on us.

  7. I feel for you Jasper. I’ve also lived in area’s where Comcast (or some other no-good ISP) was the only available broadband option. I’ve had good luck with Speakeasy DSL and now with Verizon FiOS.

    The thing with ISP’s is that they don’t always have full control over the physical wires that bring the service to your house. For DSL, the wire is actually the responsibility of whoever the major phone carrier is in your area and the DSL provider leases it from them. With Comcast, they own the actual wire on the pole, so if their service is crappy and it’s a result of bad or outdated wiring, then there is only one company to blame: Comcast.

  8. Maybe someone can help.. My speedtests are coming back normal (2400 kbps upload) but actually uploading video files to Youtube, etc is suddenly ridiculously slow (4-12kbps) Just did a chat support, and they had me go through the power cycle steps to no avail. It’s worth noting I don’t do any p2p, but it looks like video uploads might be getting flagged. Maybe a hiccup with implementation of the new data cap? I’ll be back in touch with comcast tomorrow.

  9. ryanrit: Are you using a specific app to upload the videos to YouTube, or just using the YouTube interface on their site? If you’re using a separate app, the app could be creating p2p-like traffic…

    I’d be very interested to know if something Comcast is doing is actually causing your video uploads to crap out, so let me know what you find out. Thanks!

  10. Has anyone been flat out disconnected from comcast while downloading/uploading torrents? I’m going to believe it’s the upload part that is to blame. I’m working from home and have to move thousands of server files in a migration process for work. The files themselves are not large. However, the number of files is great and I’m running 3+ streams of uploads. Though it is to one server. Whereas a torrent would be to multiple servers (people’s computers).

    I think that certain traffic patterns and behaviour lead to your internet getting disconnected. It has happened with large torrent files and it was only temporary. I didn’t have to reset the modem and I could get back on within maybe 15minutes tops. However, with this larger issue that I had – I was transferring files just fine for 6hrs+ all day while working. It was only after work hours that my internet went out and I had to actually reset the modem. I even had to call them a second time.

    I most definitely am convinced that Comcast throttles or disconnects service under certain conditions. In my case, there was nothing ever illegal. Do they want to claim I’m using the internet for business when I’m just working from home temporarily??? Come on.

    • Hey Tom,

      I haven’t had Comcast as an ISP for awhile now, but I wouldn’t be in the least bit surprised if Comcast was cutting people off based on traffic patterns. I’ve heard that ISPs are trying to do more to disrupt botnets, and one of the things they do is look for traffic patterns generated by trojan horses.

      Thanks for your comment and for sharing the information!