monitor ip address usage

Hi,

Is it possible to like see which ips are using the internet.

Say for a simple office setup.

all the computers are on a dhcp and no fancy settings.

Just normal NAt router.

Reason im asking is:

the otherday i was using the net. and i loged into the router and the internet usage was like full.

and i wanted to know who was downlaoding.
So i went into proxy and u can only see the sights under cache.

I was wandering is it possible to like access or code a feature than kinda keeps an eye on each ips throughput ?

Just an idea i had.

Mirror port with Wireshark
Torch
The built in traffic sniffer
/ip firewall connection tracking
Queues show their usage, if they are by IP you can see who is causing traffic

oh thanks,

I cant belive i have never seen that before ???