Once installed, OpenNMS scans the network to automatically discover available services, essentially anything running on a port within your network. Then it polls those services (every 5 minutes, by default) to check availability. If there are outages, it will try to isolate the problem to help you respond. For example, it will try to determine if the problem is a single application or an entire section of the network. Once the problem has been isolated, it can record the event, run any pre-configured script, send emails or pages and create a report. Check out the OpenNMS group site for commercial support.
This was first published in June 2006