I have been advertise prefix from 1 ISP successfully. Currently can use my IP to VPN with several users too.
But now I’m try to advertise the same prefix to the second ISP from different Vyos router (different location) as below screenshot diagram.
Vyos 1 - have vpn to company A and company B using ip 103.x.x.1/24
My goal is if Vyos 1 is down, all VPN users will automatically change/move to Vyos 2.
ISP A is from europe and ISP B is from asia.
Currently I’m using prepend to make Vyos 2 as a secondary.
When I start to advertise 103.x.x.x/24 from Vyos 2 to ISP B, I still can ping 103.x.x.1 which is good and VPN to company A is still up. Traceroute to 103.x.x.1 from Company A its going to ISP A which is also good.
But the issue is my VPN to Company B is down. Traceroute to 103.x.x.1 from Company B shows that its going to ISP B instead of ISP A. When checking with ISP of Company B, ISP B is a close AS neighbor with them.
Why is this happen? is prepend is not good enough to make Vyos 2 as a secondary route?
What can I do the fix this?
Can I use BGP med/metric instead of prepend?
If so, do i need to bring up iBGP between Vyos 1 and Vyos 2 to make this work?