Redistribution between BGP and OSPF

[chelle_230]

Dear sir,

This is regarding Redistribution between BGP to OSPF. We have two Branches (Location A & Location B), From Location A We are tying to connect 
location B by OSPF for google peering ( In Network diagram AS no 800 i have taken as google AS ), from Location A is it possible to redistribute only AS No 800 advertisements to location B through OSPF, if it is possible please let me know.

For testing we have configured OSPF between location A and location B, it is not taking expected path (Location A > Location B > AS=800 ) 
it is taking BGP Path to reach AS No 800 (Location B > AS=700 > AS=300 > AS=800). kindly let me know the configuration to fulfill the requirement.

Please check the attached network diagram, it is similar to our network.

thanks in advance.

Regards

Narendra

[vivek srivastava]

Have you configured iBGP between R1 and R5 ??

[chelle_230]

No, We have not configured IBGP.  My higher authority is planed to do OSPF only in between two locations. 

[vivek srivastava]

can you share the output of "sh ip bgp" on both R1 and R5 ?

Need to check the as-path from both routers.

[chelle_230]

Please find the attached screenshots.

[chelle_230]

kindly help me on this.

[vivek srivastava]

Hi, Sorry for the delayed respone.

Can you pls explain from where to where you want to reach. and via which path. I'm not able to to get that clearly from ur initial post.

it is not taking expected path (Location A > Location B > AS=800 )

-- location B is not connected to AS800 directly

it is taking BGP Path to reach AS No 800 (Location B > AS=700 > AS=300 > AS=800). kindly let me know the configuration to fulfill the requirement

-- orrect as from R5, egbp path will be preffered over OSPF. so i asked to configure ibgp between R1 and R5.

from Location A is it possible to redistribute only AS No 800 advertisements to location B through OSPF

Yes possible but ibgp option is a lot more easy.
 

[chelle_230]

We need google peering for R5 (location B). We have already google peering at R1(location A). Now we have to reach R1 for google peering from R5( R1to R5 ospf). Apart from R5 to R1 remaining all links are in  BGP configuration.

In this test document i have taken google AS No 800. We have to reach from R5 to google (AS No=800) through R1.

By default it is taking bgp path for all routes, If i decrease the AD of OSPF all routes are going through R1.  

[vivek srivastava]

Try with below config on R1:

!

router bgp 100

 network <R5 internal networks> mask <mask> backdoor

!

Then in downtime, on both R1 and R5 clear the routes. (i hope you are simulating on gns)

clear ip bgp *

clear ip ospf proces

clear ip route *

[chelle_230]

Yes for testing I am doing on GNS, is there any difference from live to GNS.

i have checked with the above configuration, it is not working.

[Rolf Fischer]

Hi,

By default it is taking bgp path for all routes, If i decrease the AD of OSPF all routes are going through R1.

Not sure if that will meet your requirements, but you can control with an ACL which prefixes will be installed with a non-default AD:

(config-rtr)# distance 19 [<RIDs> <WCM> [<ACL>] ]

RIDs: Neighbor OSPF Router-IDs

WCM: Wildcardmask

HTH

Rolf

[vivek srivastava]

Hello Narendra

Have you tried Rolf's recommendation ??

[chelle_230]

Sorry for delay, thank you for the update.. It is working  now.