Server switching: yesterday and tomorrow

Server switches distribute incoming request traffic across the nodes of Internet server clusters and Web proxy cache arrays. These switches are a standard building block for large-scale Internet services, with many commercial products on the market. As Internet applications and service architectures continue to evolve, the role of server switches and the demands on their request routing policies will also change. This paper explores inter-related factors shaping the role of server switching. These factors include the emergence of content delivery networks, the increasing prevalence of dynamic content, persistent connections in the HTTP 1.1 standard, the changing nature of Web server clusters and the opportunities to apply server switching techniques to service protocols other than HTTP. We outline the potential role of server switches in virtualizing IP-based storage protocols and as a foundation for adaptive resource provisioning in server clusters.