Thanks for the reply. The plan is to receive full routes from ebgp on router F. I believe it is rational to run ibgp on router F, as well as D and E, though I seek the reasoning to justify doing this for others here. How would we inadvertently blackhole routes, though ?

If the border routers exchange Internet routes via iBGP with a IGP next hop going through router E and D and that these routers do not have a route for these specific routes, tha packets will be dropped.

The issue is that you can't efficiently use default routing on E and D when you have multiple exit point. This could also lead to blackholing the traffic.

but i would not like to suggest full routing on 72xx with 128MB RAM i have seen problems that router disable CEF due to memory problem. yes if you have easy way to get the RAM to 256 than could be best solution with Route reflectors

Thanks for the reply. I'm planning to upgrade the c7206 Router F to replace the NPE-300 with a NPE-G1. I am also concerned about memory utilization on the 7206 with just 128M ram. I am mainly concerned about scalability and functionality for IBGP between F and routers A, B, and C.

You are right on the 7200s. Without knowing the network it is hard to make any kind of recommendation but another solution could be to take router E and D out of the forwarding path.

One more thought. If this is a SP type of environment it would be worth considering running MPLS where D and E could be P routers and wouldn't need to maintain full routing table but just the IGP routes.

My two cents.