qouta from squid

[salah khater <sal2com@xxxxxxxxx>]

Hi .
How can i use squid (or 3rd parity) to assign qouta for subnets.
I have 3 subnets and I want to give each subnet qouta,
for example: subnet1 have quota 20GB per day/week/month,
subnet2 have 30Gb per day/week/month,
subnet3 have 25GB per day/week/month.

thanks for all