I just want to share my solution of ospf stopping working after upgrade from v6 to v7, so others can find it. The default behavior of sending an LSA generated out of a static route was changed, the forwarding address field before with v6 was 0.0.0.0, with v7 the gateway of the route is inserted in this field. This breaks functioning with ospf on Routeros v6, v7 plus Bird on Linux.

You can overwrite this field with 0.0.0.0 in the routing filter to make the router working again

/routing/filter/rule
chain=ospf-out rule="if (dst in 0.0.0.0/0 ) { set ospf-ext-fwd 0.0.0.0; accept; }"

As this is a major unexpected change which breaks setups it should be mentioned in the v6 to v7 upgrade guide

Read here when forwarding address is added
https://help.mikrotik.com/docs/display/ ... ingAddress

Actually all my other routers ignore routes containing the forwarding address set and skip the route from the routing table entirely, they are also running the same router os v7.15.1 (and v6 and Bird).
The docu says that when the forwarding address is not reachable for the other router it should generate a route through the sending router, but that does not happen.

So that might be a nice feature that in my case simply breaks any routing. this behavior is different from v6.49. I wanted to let other searching for answers know this possible solution.

It's impossible to tell anything more from a given info, but from a description, it looks like a misconfiguration on the network where one router has forwarding network actually resolvable.