None,
They simply prioritize some ports above others, meaning real time traffic (SSH, Telnet, etc) will travel faster than any bulk traffic, and more important bulk traffic (FTP, SMTP, HTTP) will travel faster than any other traffic.
Basically, this means, if all the other users on the same DSLAM as you are dowloading via HTTP, you have about a one in a million chance of getting packets through on unregistered ports used by your average P2P applications.
Willie Viljoen
Web Developer
Adaptive Web Development
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