Release : 21.2.x
Component : Spectrum Discovery
We can monitor reachability using ICMP even the SNMP is not available.
From below screenshots the device is IP Device without SNMP, you can see the Poll Interval (sec) this will help the spectroserver when to ping the device for reachability.
You will not find it as ICMP Poll, the poll interval is nothing but icmp ping inteval.