OSPF Redistribution

RouterOS Forwarding Protocols
1

Hi

I have a router that has two gateways for the default route. For one, I am learning this through OSPF. This router is learning this route fine, no issues. The route appears as a LSA, everything looks good. I then install a static route for the other default route out via a different path, which I need to redistribute via OSPF as well to ensure that if the primary OSPF route fails, this new route is learned through the network. This is great as there is a LSA for this secondary default as well.

All looks good, the static has a high distance so is essentially disabled, and the primary OSPF learned default is in the routing table.. If, however, either the originator of the original OSPF learned default route restarts or loses connection, OR the OSPF service is restarted on the router, the static comes into active state, NOTHING I CAN DO will make the original OSPF learned route come into the routing table again, unless I disable the static. Its bizzare. Im sure I understand OSPF and distances well enough to believe this should work without issue, but I just cant getting this to go. Its a issue because the rest of the network needs to learn about the secondary static route via OSPF, and cant unless I redistribute it.

Any help appreciated
Brad

2

Can you post your configuration and the output of

ip route print
3

Hi - thanks for your response.
I now have this simulated in a lab environment where I can repeat the issue. The attached is a diagram of the lab network. Description of each device below:

  1. MT03 simulates a ISP - AS100. All its doing is presenting to its customer a default route via BGP.
  2. MT02 acts as the customers BGP egress route which is taking this bgp learned default route and distributing this into OSPF.
  3. MT01 acts as a router in the network that also has another connection on campus acting as a secondary path. In this lab environment I have this installed as a static default route with a high distance and as a blackhole route. In our live environment, however, the behaviour is the same, regardless that the default route uses an actual connection.

I have included attachments with the config and LSA data base. I have shown where the LSA exists for the primary (BGP redistributed route) and for the redistributed static route. In this case the static blackhole route is being used to simulate the secondary link.

Any help appreciated
Brad
schematic.gif
Mitrotik2.txt (2.64 KB)
Mikrotik1.txt (2.49 KB)
Mikrotik3.txt (1.4 KB)