Failover in ospf

(Ali N) #1

I am asked to configure a new Cisco router in multi-area ospf as follows:

  1. Setup a Gig interface (connected to MPLS) in ospf area 1 so that it works in a normal way.
  2. Setup a failover to another Gig interface (connected to a slower interface) in ospf area 2 for a failover from MPLS.
  3. Both interfaces work well one at a time, but I do not know if this kind of failover is feasible/possible and if it’s possible, how to achieve this.

Thank you.

(Lazaros Agapides) #2

Hello Ali

If I understand correctly, this is the configuration:

To answer your question, yes it is possible to make this work. There are several ways that you can go about it.

  1. Routing - If the router has some OSPF relationship with the next hop routers in areas 1 and 2, then it can be informed of loss of connectivity to networks that are further downstream. The router will then revert to the secondary connection in order to reach those networks. This will work especially if routers in Area 1 and Area 2 pass on default network information, meaning that the router will be informed of the default network. You can adjust interface costs in order to influence the OSPF routing so that the MPLS connection is preferred.
  2. IP SLA - Using an SLA such as a ping to a particular network via the first interface, in the event that a ping fails, you can insert another alternate route into the routing table. More about this can be found here:

I hope this has been helpful!