Internet Accounting and Billing

Hi,

We have a small network on a hotel and one of our service is providing our guests with internet connection via ethernet. We use a Cisco Catalyst 3500 series xl. We bill their usage per day but it's not accurate since we are not using any software to track the internet usage.

What software can we use to track their internet usage and at the same time can provide report that can be use for billing.

Thanks in advance!
--sparksd--