Anycast Request Routing for Content Delivery Networks

This chapter discusses request‐routing mechanisms in modern content delivery networks (CDNs), and, in particular, argues for viability of Internet Protocol (IP) anycast as the basis for request routing. IP anycast refers to the ability of the IP routing and forwarding architecture to deliver packets to the closest among a set of possible endpoints. Standalone CDNs, such as Akamai, connect their servers to various ISPs; thus maintaining presence in multiple autonomous systems. A CDN operated by a global ISP can have sufficient footprint while deploying its nodes at various points within the ISP's own autonomous system. The chapter presents a general lightweight IPv6 anycast protocol for communication utilizing connection‐oriented transport, and then uses this protocol to design an architecture for an IPv6 CDN based on anycast request routing.