I think this is a simple question but I’ve worked through all the BGP lessons and can’t seem to find a clear answer.
I have a router running BGP that has two ISP’s (A and B) as neighbors.
We want all of our incoming traffic to go through ISP A, but if ISP A goes down, ONLY THEN use ISP B.
So my first thought is to use AS prepending on the routes we advertise to ISP B, I added our own AS 5 times, and it seemed like everywhere would prefer to use ISP A as the best/preferred route.
However, this didn’t work as I intended as when I checked ISP B’s looking glass, they were using the direct route prepended with our AS.
So my question is how do I set up the scenario where I want all incoming traffic to flow through the neighbor corresponding to ISP A unless ISP A is down?