By default, Net-SNMP does not publish the full SNMP tree. Check to see if that is currently the case on a device and configure it correctly.
Confirm snmpd is running:
> snmpwalk -v 2c -cpublic <your device name> system
Retrieve the IP table for the device with snmpwalk:
> snmpwalk -v 2c -cpublic <your device name> ipTypical SNMP View:
view systemview included .1 view systemview included .220.127.116.11.18.104.22.168 access notConfigGroup "" any noauth exact systemview none none