I don't understand well OSPF, but following the manual got it working on mesh of 5+ routers.

one of them is attached to subnet (192.168.100.0/24) managed by 3rd party router. I want to advertise the route to that network.

the MT router is assigned IP 192.168.100.1, the router on the other side has 192.168.100.2. The connecting interface is *not* bridged, on purpose.

the MT router properly advertises it's own IP, routing works correctly, etc. When on remote box I set-up static route to 192.168.100.x via 192.168.100.1 everything's OK.