Hello Arivudainambi
In the scenario that you are describing, R4 will have information about the 6.6.6.6/32 prefix from eBGP, via R6, and from iBGP via R2. In such a case, by default, the eBGP route is considered to be the preferred route. But the comparison here has nothing to do with the BGP attributes, but with the Administrative Distance. Varying routing protocols have different administrative distances, such as:
- 0 connected interface
- 1 static route
- 20 eBGP
- 90 EIGRP
- 110 OSPF
- 200 iBGP
As you can see, iBGP has a much larger AD than eBGP, so by default, eBGP routes will be installed in the routing table over iBGP. So there is no BGP-specific “backup” mechanism that you can apply in such a case, such as additional paths, or multipath.
If you want to manipulate the routing in this case, you will have to adjust the AD. In general, this is not a good idea to do, especially in a topology like this one. It can result in an unstable topology. However, there is one particular case where this is applied by design, and that has to do with BGP backdoor routes, where this configuration changes the AD of the eBGP learned routes for a very specific purpose.
Take a look at this post as well which further describes the reasoning behind it:
Keep in mind that this should only be applied in very specific circumstances in order to achieve something specific. In general, eBGP should always win out over iBGP learned routes.
I hope this has been helpful!
Laz