how anycast work. https://www.slashroot.in/what-anycast-and-how-it-works
https://www.incapsula.com/blog/how-anycast-works.html
https://www.cloudflare.com/learning/cdn/glossary/anycast-network/
https://blog.thousandeyes.com/using-anycast-for-internet-services/
http://usc-nsl.github.io/cdn-coverage/
https://engineering.linkedin.com/network-performance/tcp-over-ip-anycast-pipe-dream-or-reality
as numbers. http://www.iana.org/assignments/as-numbers/as-numbers.xhtml