SDN: Do not enable OSPF on interfaces without IPs configured
Starting now there will be (VLAN) interfaces without any IPs configured
besides IPv6 Link-Local Addresses. Those interfaces/VLANs will be used
as underlays for Data Center Interconnectes (DCI) for B.A.T.M.A.N. adv.
meshes for example. As IP connectivity already is present on DCI links
there is a need for interconnects solely for B.A.T.M.A.N. adv. which do
not require any assigned prefixes. On the underlay interfaces only LLA
addresses will be used for VXLAN VTEP termination.
Signed-off-by: Maximilian Wilhelm <max@sdn.clinic>