the last few days i´m trying to get an ospf connection over an ipip or pptp tunnel to a cisco router working.
it seems that the ospf process stucks at the mikrotik side. the cisco is sending and receiving hello and acks correctly, but no routing information is exchanged.
i´ve read on this board, that there is an problem with ospf over ipip - but does anyone know whats the problem is? is there an update planned for the future?
switching over to rip, or use an l2tp tunnel is not an alternative
With OSPF, the interface MTUs must be the same for all routers participating on that segment. But, it seems like Cisco and MT have slightly different ideas of what exactly the MTU represents on non-ethernet interfaces.
I think this is actually a Cisco issue, since we also see similar things with non-MT neighbors.
For the most part, we have mainly had trouble with ATM DSL PVCs, but have seen it with tunnels as well (but we don’t really try to do that sort of thing anymore).
To get around it on ATM DSL PVCs, we bridge the PVCs on the Cisco to ethernet VLANs, and connect those to another MT. Thus, the Cisco does not need to participate in OSPF anymore, and can have a large MTU. I’m not sure if you could work it out this way with tunnels, though.
The best idea would probably be to jump over the Cisco with your tunnel, and just terminate it (and run OSPF on) another MT.
I’m not sure what may be wrong with MT’s IPIP, since we just use L2TP (which works quite nicely with OSPF).
