This is a feature request for adding 'dummy' type virtual interfaces.

  ip link add frob0 type dummy

Has no parameters of its own (besides name) – only the generic IP configuration, MAC address, etc.

Use cases:

 * Sometimes you have e.g. a VM bridge whose ports come and go, and you want it to remain 'UP' despite having no VMs running at the moment. There doesn't seem to be a bridge setting for that (a bridge with no ports always shows up as 'NO-CARRIER', and I don't think NM even allows _configuring_ empty bridges), so you add a dummy interface as a port.

 * When configuring a router or a multihomed host, it's common to assign IP address to the "loopback" interface (e.g. because they're reachable through several networks but don't actually belong to any of them). But some programs can't handle 'lo' well, so a separate dummy0 is often used instead.