gary shaped adsl means simply that non priority port numbers, that is to say port numbers that arent 25, 53, 21, 80, 110 et are throttled. It means you wont get full speed on all protocols
thats port shaping then there is packet shaping which means all your traffic is inspected and if you are sending 'bad' traffic like p2p traffic it will be slowed down.
They slow it down by simply pooling data, think of it like your data streams in if its on a bad port or its bad traffic it is redirected to a bucket, that bucket is set to empty every second or so so you get erratic burts of data every second or so, they do it like that to reward the patient (who will only notice the data burts when they need it) and to punish the bandwidth hogs (who will notice a gap where the traffic flow stops when they try hit it too much)
