How hard is it to implement a system in a (say) university so exceeding a bandwidth limit will throttle your connection to a crippling but still useable speed?

Context: the computer office of my college is introducing a flat £10/gb fine for every gb over 5gb in a week. He says it's too much time/effort/money to do throttling.

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“There are some people in this world who don’t love their fellow man, and I HATE people like that!”

depends on what you have in place mate
do you mean to make something from scratch or buy in a peace of kit to do it for you
it wouldnt be to hard to make something tbh i have done this in the past but never when a limit is hit
more to the point - is this to stop students / staff p2p`ing ?
if so a packeteer would be a better solution, we had a similar traffic policy and its a nightmare to run
also - you have to be able to produce the logs when a student contests it.
on the first day we had loads of students - mainly asians turning up with bills from 100 to 450 quid
the problem is, until they disconect and then reconect the session data is a variable and on our campus it would have been a nightmare to do that so there was a cron job that polled the routers every 10 mins and they got disconected that way. hence if they left there machine on for 3 days they could easly go over
there is also ( depending on the topology ) ways around it, run the uni vpn client on campus etc
or like i do with virgin - drop the correct flags with iptables to stop them reshaping the TCP window
below are sample global TCP flag variables:
urg: tcpFlags = 0b100000! -> `Urgent Pointer field significant'
ack: tcpFlags = 0b010000! -> `Acknowledgment field significant'
psh: tcpFlags = 0b001000! -> `Push Function'
rst: tcpFlags = 0b000100! -> `Reset the connection'
syn: tcpFlags = 0b000010! -> `Synchronize sequence numbers'
fin: tcpFlags = 0b000001! -> `No more data from sender'

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"If your going to kill a man, it costs nothing to be polite."- Winston Churchill
three and a half foot long??? dude, it could have swallowed you whole! 3jorn=GCHQ=