Allow changing MTU when interface has vlans
When one creates a vlan interface, later he cannot add the parent interface with an empty ip configuration with options only, where he would enter the 'mtu 4000' ifconfig arguments, for example.
#4 Updated by Richard Kojedzinszky over 4 years ago
So, when you create an vlan interface, you later cannot add the parent interface with mtu options only, as it is not present in the dropdown list.
I assume in FreeBSD first the underlying interface's mtu has to be changed to allow changing the mtu of vlan interfaces.
And you can have a configuration, which cannot be reproduced later without service disruption.
The steps: assume you have an em0. You create a vlan1 interface on it. Now under the interfaces menu you add the vlan1 interface with IP settings, and probably remove the em0 entry.
Later, you cannot re-add em0 as it is not in the drop-down list. Just if you remove all vlans associated to it. Also, it makes impossible to use an interface in trunk mode with one vlan in native mode.
Did you catch my intentions?