Mailing the story:
Zabbix: State-of-the-art network monitoring
I have used BigBrother and Nagios for a long time to troubleshoot network problems, and I was happy with them -- until Zabbix came along. Zabbix is an enterprise-class open source distributed monitoring solution for servers, network services, and network devices. It's easier to use and provides more functionality than Nagios or BigBrother.