count active users in a wisp network

Hi,

In order to fine-tune the available bandwidth and the p2p rules I’m wishing to know the active users in a period of time (eg. each minute or each 5 muntes). For me, an active user is one that has uploaded+downloaded > X bytes in a period.

I have a group of APs connected to a mikrotik rb1100 which has two kind of customers: pppoe and dhcp.

I don’t know how can I focus this: mangle rules? script? from the radius accounting updates? (but this will work only for the pppoe customers, not dhcp customers). I don’t want to poll each CPE; I’m interested in doing this centrally at the rb1100

Anybody has any idea how to deal with this?

Thank you very much !!!
Antonio

http://wiki.mikrotik.com/wiki/Manual:IP/Traffic_Flow
There are several free Netflow collectors available, such as ntop.