It's optimized for polling tens of thousands of counters on hundreds or thousands of hosts in a parallell manner. This is known to work (although performance might be limited by less than optimal SNMP agent implementations in random network gear). Create a Session. The Session constructor, like most of the other functions, take an options object. The options passed to the Session will be the defaults for any subsequent function calls on that session, but can be overridden as needed. Useful parameters here are host, port and family.