Content distribution architecture using network layer anycast

Abstract

Server replication is a common technique for distributing content efficiently and in a scalable manner to many clients. Directing clients to the "best" of these content-equivalent servers is a non-trivial problem. As a solution, we propose CDAA (Content Distribution Architecture using Anycast) that uses replicated servers and leverages the idea of anycast, supported at the network layer, to direct clients. CDAA assigns the same anycast address to content-equivalent servers and tracks the load on each of them. This information is used to direct clients in the network to the "best" server, improving user satisfaction by reducing the response time seen by the clients. CDAA is scalable, incrementally deployable and transparent to existing network applications and protocols. These objectives are achieved with minimal bandwidth overhead and computing requirements. Though the DNS (Domain Name System) and client software require some modifications, the routers and servers remain unchanged. We also present simulation results that demonstrate the efficacy of our architecture.