Normally you would use anycast to get you to a DNS server (which doesn't have to be that near), then a geographic DNS server to get you to the right CDN element.
That's what I was doing previously, but I need to control the IPs for the CDN, and I only have the budget for one /24, so I'm trying to make the best of it. Aside from some occasional weird routing, the network has worked really well. State has not been an issue for what we're doing (short-lived HTTP connections). I'm just trying to see what the extent of my powers to control weird routing are. It's odd to see Comcast cold-potatoing connections to the wrong routes, sometimes on the other side of the continent ( https://gist.github.com/kyledrake/7a4cd36ea276ec3134b4a51a42a37f48). I'm wondering if there is a way to configure Bird to help steer these sorts of things a little better, even if it's on a case-by-case or region-by-region level. My apologies if these are all dumb questions. Again, not much anycast documentation out there (I'm planning to improve this later by putting together a web resource for people doing this). -Kyle