BGP OSPF distribution, route manipulation

Unanswered Question
Mar 28th, 2010

Say for example that the site "DR" in the drawing is logically divided into two sites A and B, A and B both have mutilple subnets.

If I wanted site A to prefer the ospf routes to "HQ" and site B to prefer the BGP routes to site "HQ", but A and B would use the available link if one were to fail,

What would the best way to have control of this scenario without causing a loop?

The distributed routes from BGP to OSPF will have either and E1 or E2 designation, while the OSPF routes in the same area will be preferred.

I don't know of a way to manipulate the intra area routes to prefer a distributed route, force an intra area route to be and E2 route for example.

I am thinking the options are the following, please someone let me know what could be wrong with my thinking:

1. Use prefix lenth and route maps on the distributed BGP routes into OSPF. Use longer mask to control which routes go where (across

2. Configure DR to be a different area than area 0, I am thinking this would allow me to control the O ( internal to each respective area), IA and E (distributed) routes.

3. Configure DR as EIGRP, which would allow control of the routes distributed from EIGRP into OSPF, the problem with this is that I am ditributing BGP into EIGRP into OSPF, which seems like a convoluted way to do things.

Any opinion would be appreicated.

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Laurent Aubert Sun, 03/28/2010 - 13:15

Hi,

If site A and B can use a different router to join HQ then on each router playing with the AD should be enough. If they are using the same router, you will have to use PBR or VRF (more complicated as it impact your design globaly).

HTH

Laurent.

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