It´s the bufferbloat stupid

CeroWrt – Debloating

I don´t know if you heard about Bufferbloat yet, i posted a google tech talk a few weeks ago regarding this issue.

I would recomment watching it, to get a brief overview of what it is about. A few days before i mentioned that there is a interesting project called  CeroWrt , whitch claims to work on this network buffer issues.


Bufferbloat is a widespread problem present throughout the Internet, “end-to-end.” Debloating is a “work in progress” industry wide and will take years. Ultimately, all buffering/queuing in operating systems needs to be carefully managed and be automatically adaptive to the data transfer rates. All network routers (and operating systems!) should be running with AQM (e.g. algorithms such as RED) including home routers: unfortunately, existing algorithms such as RED are unlikely to work correctly in today’s home network environment.

CeroWrt is the test platform for improved AQM algorithms. To achieve ultimate latencies under load across the high bandwidth variation of 802.11 and broadband, new AQM algorithms need testing in addition to more complex changes in internal buffering; these will take time and therefore debloating will be a work in progress for an extended period.

In the upstream direction, the bottleneck link may be adjacent to your home devices (e.g. your laptop on wireless), and in your operating system, outside of our control; you may see problems therefore copying from your home device upstream to the Internet and/or your home file server. Unfortunately, TCP acks can be stalled behind packets queued in a particular direction, so bufferbloat in one direction can result in bad performance (poor latency) in the other direction. If you run Linux, you can help with debloating by working with those working on the debloat-testing work going on on On other operating systems, you should contact your operating system vendor and complain. Be gentle (but insistent), however: before 2011, bufferbloat was not understood to be a general problem, and it will take time to overcome.

Note that bufferbloat only occurs in the device just before the bottleneck in a path. A common strategy when fixes for bufferbloat are not available for the devices either side of a bottleneck, therefore, is to try to arrange to move the bottleneck from a device which is badly bloated to one which is not: e.g. you might arrange to ensure that your wireless bandwidth is always bigger than your broadband bandwidth (and using bandwidth shaping and QoS to avoid the consequences of bufferbloat in that hop as best you can).


Check out daves blog


Bufferbloat: Dark Buffers in the Internet Download PDF version of this article

by Jim Gettys, Kathleen Nichols | November 29, 2011

Topic: Networks




Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s