Glasnost: These ISPs are Shaping Traffic!

   

During NSDI '10 (the 7th USENIX Symposium on Networked Systems Design and Implementation, held on April 28-30 in San Jose, CA), project "Glasnost" presented its methodology and findings regarding traffic shaping practices by ISP.

Glasnost is a research project done at the Max Plank Institute for Software Systems. Its goal is to "to make access networks, such as residential cable, DSL, and cellular broadband networks, more transparent to their customers." The research, led by Krishna P. Gummadi provides a list of ISPs that were detected to do shaping.

Here is an extract from the paper:

Note that the tests were conducted over a year ago. Since then, lots of DPI/Traffic shaping gear was sold and implemented - also by mobile (3G mainly) operators not covered in the above table.

An interesting finding is that operators tend to shape upstream traffic more than downstream. This maybe explained by a number of reasons, including:

• Upstream has lower capacity in most access technologies, and fills faster with P2P sharing uploads, also is also effecting downloads (as all TCP traffic is bi-directional)
   
• Uploading files serves "off-net" users and does not drive complaints or [expensive] calls to the help-desk

Also, it seems that most ISPs are shaping using DPI as they detect the application (layer 7) rather than the TCP port (layer 4). About half of the ISPs are shaping only during peak hours.

See "Glasnost: Enabling End Users to Detect Traffic Differentiation" - here (paper) and here (presentation)