If people have heard of bufferbloat at all, it is usually just an abstraction despite having personal experience with it. Bufferbloat can occur in your operating system, your home router, your broadband gear, wireless, and almost anywhere in the Internet. They still think that if experience poor Internet speed means they must need more bandwidth, and take vast speed variation for granted. Sometimes, adding bandwidth can actually hurt rather than help. Most people have no idea what they can do about bufferbloat.
So I’ve been working to put together several demos to help make bufferbloat concrete, and demonstrate at least partial mitigation. The mitigation shown may or may not work in your home router, and you need to be able to set both upload and download bandwidth.
Two of four cases we commonly all suffer from at home are:
- Broadband bufferbloat (upstream)
- Home router bufferbloat (downstream)
Rather than attempt to show worst case bufferbloat which can easily induce complete failure, I decided to demonstrate these two cases of “typical” bufferbloat as shown by the ICSI data. As the bufferbloat varies widely as the ICSI data shows
, your mileage will also vary widely.
There are two versions of the video:
- A short bufferbloat video, of slightly over 8 minutes, which includes both demonstrations, but elides most of the explanation. It’s intent is to get people “hooked” so they will want to know more.
- The longer version of the video clocks in at 21 minutes, includes both demonstrations, but gives a simplified explanation of bufferbloat’s cause, to encourage people to dig yet further.
Since bufferbloat only affects the bottleneck link(s), and broadband and WiFi bandwidth are often similar and variable, it’s very hard to predict where you will have trouble. If you to understand that the bloat grows just before the slowest link in a path, (including in your operating system!) you may be able to improve the situation. You have to take action where the queues grow. You may be able to artificially move the bottleneck from a link that is bloated to one that is not. The first demo moves the bottleneck from the broadband equipment to the home router, for example.
To reduce bufferbloat in the home (until the operating systems and home routers are fixed), your best bet is to ensure your actual wireless bandwidth is always greater than your broadband bandwidth (e.g., by using 802.11n and possibly multiple access points) and use bandwidth shaping in the router to “hide” the broadband bufferbloat. You’ll still see problems inside your house, but at least, if you also use the mitigation demonstrated in the demo, you can avoid problems accessing external web sites.
The most adventurous of you may come help out on the CeroWrt project
, an experimental OpenWrt
router where we are working on both mitigating and eventually fixing bufferbloat in home routers. Networking and ability to reflash routers required!