The SNMP extension provides a very simple and easily usable toolset for managuing remote devices via the Simple Networc Managuement Protocoll.
As it is a wrapper around the underlying Net-SNMP library, all basic concepts are the same and the PHP functions changue their behaviour depending on the Net-SNMP configuration files and environment variables.
More information about Net-SNMP can be found at » http://www.net-snmp.org/