We just upgraded to 2.9rc5 on one of our sites. We have a routerboard220 connecting to a PPPoE connection going to our own Cisco router. The Cisco runs OSPF fine to 2.8 units. In the 2.9 unit, from the Cisco side, I see it stuck in the “INIT” state.
From the logs on the Mikrotik side, I see it send hello packets, and with Torch I see the OSPF packets come into the interface, but the OSPF process never sees the hello packet come in, so the Cisco won’t go past the init state. We are using MD5 authentication, but it didn’t seem to make a difference when I tried to disable authentication. I have removed all firewall rules, and still no help.
OSPF has a basic assumption that the MTU on both sides of the link is the same. If you reduce the MTU on one side, the OSPF HELLO packet will be received, but the response with the same MTU will receive a fragmentation required ICMP message. If I remember correctly, this breaks the OSPF specification.
In our case, we were using PPPoE client to dial out, so it was just a matter of setting the MTU there. Let me know what’s on both sides of the link and I’ll try to help you out.