Sorry, looks we posted at the same time. How about Net::Ping? What are you looking to do? I can keep throwing CPAN links all day :)

I think you might reread some of the SNMP docs. An agent responds to a SNMP request. From Net-snmp -- snmpd:

snmpd is a SNMP agent which binds to a port and await requests from SNMP management software. Upon receiving a request, it processes the request(s), collects the requested information and/or performs the requested operation(s) and returns the information to the sender.

You might also checkout net-snmp's homepage.