I had nodes in Orion that were missing from IPAM. The was marked used due to ICMP, but had no SNMP data. I finally figured out why.
When you setup your SNMP credentials in IPAM it defaults to v2. There is a checkbox on the page that says V2c only. I assumed that meant that that it would try V1 as well as V2 unless that checkbox was checked.
That is NOT what was happening. I ended up having to create TWO credentials for each community. One for V1 and one for V2. I run the V2 first since its more efficient, but I'm not sure it matters when you are just getting SNMPv2 device information.
I'm not sure that's as expected. The manual didn't say anything on this that I can remember. At the very least, I would default to v1 for new credentials since that would work on most devices. But trying both is the way Orion scans.
-=Dan=-