I am trying to monitor how much bandwidth is being used by websites(vhosts) on my iis (7.5) machine. on a per site basis. Is their a cacti plugin or configuration guide that i can use to monitor this. My cacti setup is running on a ubuntu 11.04
The only way to monitor upstream bandwidth usage for individual IIS websites is by counting the sum of the "sc-bytes" value for each request in the IIS W3SVC logfiles.
There are several approaches to this, eg. generic log parsers, bulk importing logs to a database, direct read and aggregation from the daily logs, etc.
I don't think there is a cacti plugin available but these custom user submitted graph templates might point you in the right directions: http://forums.cacti.net/about12464.html
You might wan't to check out the IIS Log Analyzer, a comprehensive extension of the IIS log parser. You could set up a scheduled task to run the analyzer, and sum up the daily traffic flow in any txt format for cacti to read.