I 'bookmarked' these folks: http://www.plus.net/?home=hometop on June 18, 2008 because they were one of the few who openly admitted to using DPI to enforce QOS.Two + years later, they're still around and apparently successful. Just glancing through the site, I could no longer find any mention of DPI, but instead they say this:
http://www.plus.net/support/broadband/speed_guide/traffic_management.shtml
For what it's worth...
