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OSPF to BGP Route metrics

We copy large amounts of data from a host in site C to a host at subnet 10.234.0.0/22.  I have two paths to get from C to the host.  One is perfered by us due to larger bandwidth.  The link between C -B is a gig and B-A is a Gig.  The link between C-Z is 100 meg. 

Both of the A and Z routers are on the same OSPF area on the LAN side and different BGP AS on the WAN side.  I want to advertise the route from Z to be a higher metric so it is not the perfered route.  I want traffic from teh 10.232.x.x network to chose the C-B, B-A.  The C-Z is an alternate backup for this data copy.

How can I advertise from the A and Z router the 10.234.0.0/22 so it is a higher metric from Z than A?

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2 REPLIES

OSPF to BGP Route metrics

Hi,

don't forget you need to influence both traffic directions.

If you need just a temporary solution, the easiest way would be:

Configure two static routes on your router A:

One for the host in 10.232.0.0/16 subnet, using 10.32.255.1 as next-hop. Redistribute this route to OSPF (but not to BGP!).

Second for the host in 10.234.0.x/22, using 10.234.0.7 as next-hop. Redistribute this route to BGP (buit not to OSPF!).

As "longest match wins", router A will be always preferred for the communicatiopn between those two hosts.

Remopve those host static routes when finished with your file transfer.

If you need a long-term solution, you should reconfigure the OSPF/BGP mutual redistribution to advertise 10.234.0.x/22 subnet with worse attributes (by AS prepending, e.g.) from router Z to BGP.

And also to advertise the 10.232.0.0/16 with worse OSPF metric from router Z to the OSPF cloud.

But this is a little tricky and you need to know the curent metrics used for the routes.

HTH,

Milan

Bronze

OSPF to BGP Route metrics

Hi,

Rather than influencing the Routing Protocols, you could use Policy Based Routing to achieve this.

Kind regards,

Paul

HTH Paul ****Please rate useful posts****
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