This text is from the Glasnost Website below:

The goal of the Glasnost project is to make ISPs' traffic shaping policies transparent to their customers. To this end, we designed Glasnost tests that enable you to check whether traffic from your applications is being rate-limited (i.e., throttled) or blocked.

Glasnost tests work by measuring and comparing the performance of different application flows between your host and our measurement servers. The tests can detect traffic shaping in both upstream and downstream directions separately. The tests can also detect whether application flows are shaped based on their port numbers or their packets' payload. For more details on how Glasnost tests work, please read our NSDI 2010 paper.

We configured our tests to be conservative when declaring the presence of shaping, i.e., passing our tests does not necessarily mean that there is no throttling occurring on your link.