Just in case the subject does not say what I think it says (I'm not very familiar with this particular topic). Attached is the theoretical physical network topology.
I want to have 3 separate internet connections, one in each of my 3 facilities, all "rolled up" to provide a unified method of accessing web servers on my DMZ(s).
Each facility has a site to site link.
So, to simplify things lets assume I have 3 sites and 3 public IPs:
18.104.22.168 on site 1,
22.214.171.124 on site 2,
126.96.36.199 on site 3.
Lets assume that I have a web server NATed on 188.8.131.52, which I want to be equally available from all 3 sites (obviously preferring the router at 184.108.40.206, which I suspect it will do automagically?).
To avoid the pitfalls of Round-Robin DNS, I have a single A record pointing www.company.com
Now, I suspect that the following methods can be used:
Would likely be the best method in a perfect world, but I haven't got a /24 subnet at my disposal.
2) Static Routes + Metrics on routers
Since the links are very likely all going to be from the same ISP (lack of available alternatives) I could, in theory, just pay them money and ask them to set static routes and metrics to each of my 3 public IPs, such that the alternates (#2 and #3) would be used in the event of saturation or link-down situations. Guessing this would be incredibly messy?
In short, how can I have a single A record reachable from three public IPs, without using BGP?