Static routes on (active) interfaces without IP address set

Hi, Is there any specific reason why bird (1.6.0 @linux in particular) does not process static routes like: route 10.101.0.0/24 via "eth1"; when eth1 has no assigned IP address (but is up & active)? This route is completely legal but it is invisible anywhere, simply ignored (even does not appear in debug messages). Once eth1 gets IP address, the route is added, but not otherwise... -- With best regards, Alexander.