If you build a Network Monitoring system you will find out that there is a lot of information that you can get via the SNMP Protocol.

You have to make some choices on what you want to monitor and when you want to receive a notification about a certain event and how you want to receive it.

Start by making a basic monitoring plan, think about what you want to see:

For example:

• Disc space usage on Servers, SAN or NAS devices
• CPU usage on your most critical servers like Print, SQL and Mail Servers
• Mail Que’s fon Incoming and Outgoing Traffic
• Intranet of Internet Webservers traffic and bandwith use
• Routers Bandwith Usage and Traffic
• Ping you most critical devices
• Etc..

For all those items you write down the monitoring interval and thresholds and you gets a notification.
There is no point in sending a ping failure about a  print server to the SQL Support person..

Only if you have written this plan down you can start building your system.