Easiest way to account traffic from interfaces?

Hi,

I have a client that wants to account for traffic coming from a specific interface, is there any persistant easy way to do this, I would assume you can do it via SNMP, is this correct.

I dont want to do hotspot or anything like that, jsut all traffic going through a specific interface?

Any suggestions are appreciated.

Yes, SNMP will help you to achieve this.
You may even use built-in ‘graphing’ feature, that provide statistic about interface traffic that has been passed trough,
http://www.mikrotik.com/testdocs/ros/2.9/tools/graphing.php