I have following scenario: My AS: 64501 has two routers R3 (Redundand) and R4 (Main).
ISP AS: 64500 has 3 routers R1, R2 and R5
I have eBGP peering with ISP, I have no access to ISP configuration, only to configuration on my net (R3, R4).
I need that incoming traffic from ISP always was sent to Main router (R4) and only if Main isn't accessible send traffic to Geo redundant (R3).
I can do it using AS-PATH Prepend sent from Geo-redundant router (R3) and it's working:
But in this case traffic in ISP from R5 is sent as showed on picture (via R1-R2-R4) - one more hop, not straight (R5-R2-R4). This happens because iBGP is not using AS-PATH prepend, so R1 is preferring route via R2, as route R1<->R3 is prepended. But R1 is sending iBGP route update to R5 without as-path prepend. So for R5 there are two equal routes to My network, and it's choosing route via R1, as R1 IP address is lower that R2 IP.
Question#1: Can I configure somehow devices only in My network, so traffic will pass like this, without MED or Communities?
Questions#2: Can I configure somehow devices in My and in ISP network, so traffic will pass like this, without MED or Communities?