Comment 6 for bug 1812748

Thank you for taking the time to report this bug and helping to make Ubuntu better.

Based on your description I can make a guess as to what is going on.

The "old" kernel interface for network interfaces (still supported under Linux's interface stability promise) allowed named aliases. This is what "ifconfig" uses ("ifconfig eth0:1 ..." etc).

The new interface, used by "ip" and everything new, generalises that to a list - no specific alias names required - but supports a "label" for backwards compatibility. See ip-address(8) for details (search for "label").

I suspect that snmpd doesn't understand additional addresses attached to a network interface that don't have a label.

I'm going to make an executive call here and say that a workaround in netplan to always add a label is not feasible because that would require a suitable implementation to exist in all of its backends as well as maintenance of the labels to avoid conflicts, etc.

Therefore I think this bug can only realistically be fixed in net-snmp by supporting the new kernel interface.

With this background (that I hope is accurate), could someone verify if the latest upstream version of net-snmp still has this issue? I think it's unlikely we'll be able to fix this in Ubuntu without an implementation upstream.

Accordingly I'm marking the netplan.io task Invalid, but feel free to reopen if you think my assessment is incorrect.