2) To influence the inbound to take the path via R4.
Now, to prefer an ISP for outbound you need to set a higher local preference to the neighbor. So, that downstream traffic takes R2 to R0 path.
To prefer an ISP for inbound, you have done it correctly using AS-path Prepending.
Question of iBGP being required. I would say "yes". Because if the primary path was to fail, downstream devices would not know where to forward the request. HSRP tracking might be enabled for interface, nowadays it's all ethernet so the chances to the connected interface going down is rare. You may need to think of running IP SLA along with it to get this working else.
If you were to run iBGP between R2 & R4, then you have no such issues. Assume that the path from R2 fails, you would have another path via R4. Still the packets will be forwarded to the Active router (i.e R2) & based on the BGP table it knows the next-hop is via it's iBGP peer. It simply forwards.
i show ur configuration... just configure there inbound and outbound... when ur packet go out side there configure outbound means data out ack in and where u want to receive ur packet that side configure inbound means data in ack out.... and u need to configure ibgp for backup path or ur internal router communication .. hope this is needful
Your config looks ok. I have seen a similar issue with my own setup with IP SLA, it keeps dropping off without any genuine reason. I would suggest to avoid this feature (my personal opinion). Using iBGP would be a more viable solution for this scenario.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...