ospf external path selection with different metric.

[syjeon]

Hi,

we are planning to put the another circuit for backup traffic replication purpose between two datacenter.

there is already normal MPLS circuit, so, another 10G circuit will be installed between two datacenter.

my intention is to configure different metric when BGP external routes redistributed into OSPF on two BGP routers.

when I tested, I checked lower metric is preferred to select the routing path always.

I think it is working as my original plan. Can someone review the attached diagram and give me thought so we are fine with this approach to go?

[Harold Ritter]

Hi,

The best would be to redistribute the primary path as an external type 1 and the backup path as an external type 2. This way the primary would always be preferred over the secondary, regardless of what the topology looks like.

Regards,

[syjeon]

Hi, 

thanks, it is another workaround likely you said. in case of when BGP routes are redistributed into OSPF with type-1 in different metric, can I archive the goal what I'd like to do?

according to the test result of simulation, it did work seems the lower metric is preferred to select routing path by OSPF

[paul driver · Accepted solution]

Hello

This is a good solution we use this a lot in duel isp peerings  - the majority of the times we tend just to receive only a default from the ebgp pears and distribute a ospf default into the L3 cores with a preferred lower ospf metruc type for the primary path .wirkd a treat!

res

Paul