LibreNMS is an autodiscovering PHP/MySQL/SNMP based network monitoring
which includes support for a wide range of network hardware and
operating systems including Cisco, Linux, FreeBSD, Juniper, Brocade,
Foundry, HP and many more.

LibreNMS has grown out of a lack of easy to configure network
monitoring platforms. It is intended to provide a more navigable
interface to the health and performance of your network. Its design
goals include collecting as much historical data about devices as
possible, being completely autodiscovered with little or no manual
intervention, and having a very intuitive interface. 

WWW: http://www.librenms.org