Network Monitor and bandwith calculation with snmp and log monitoring Using Nagios or Other Monitoring Software

Hello all Network admin and professional's, I have a few servers that host multiple website, I want to monitor bandwidth consumption by each website hosted on the servers, there are 100;s of domains. We do not offer individual IPs and offer name based hosting. I need a solutions using a free software, open source, MRTG or Cacti, or anything you suggest. i need you to configure it to report on all the sites bandwith usage also i need it to do SNMP on the hardware of the servers. to monitor up time and down time, with emailing when things are down. also it would be nice to have nice graphs with everything in 1 location. Also Monitoring Veeam and Backup exec Logs to verify backups are a must. a new virtual server can be setup for you weather it is windows based or linux based. you can use: Nagios: Centreon: NagVis : livestatus broker Thruk from RPM Nagios Business Process Addon anything else that is needed.