This book addresses the concept of distributing traffic, better known as load sharing, efficiently among the multiple servers available to address a data request. It is one of the very first books on this topic. It addresses both theory and implementation issues on the Internet.

Three broad sections make up the text: “Concepts and Theories of Server Load Balancing,” “Practice and Implementation of Server Load Balancing,” and “Configuring Server Load Balancers.”

Section 1 begins with an introduction to the idea of load balancing. It briefly looks at the various methods by which load distribution can be accomplished. The reader gets a good idea of how server load balancing (SLB) is different from other approaches. After a brief introduction to the open systems interconnection (OSI) layer model of networking, the text proceeds to explain the components of a network-based SLB virtual Internet protocol (VIP). A network-based SLB virtual IP is an Internet protocol (IP) address to which traffic is sent. The server that has been assigned this IP will then distribute the traffic among the multiple available servers. The text goes on to discuss servers hypertext transfer protocol (HTTP), or any service that is being load shared), groups or server farms, and user access levels. It also addresses the methods used to provide redundancy among servers, how a data packet is handled in a load balancer, and performance metrics.

Section 2 takes at a look at network design for server load balancing. The IP address configuration can be flat-based or network address translation (NAT)-based. For flat-based address configurations, the VIP and the real servers are on the same subnet. For NAT-based address configurations, the VIPs and the real servers are on separate subnets. The basic configurations for these approaches are addressed in the rest of this section.

The book concludes with section 3, which examines configuration details of some of the available server load balancers. This list of balancers includes Alteon Websystems, Cisco’s CSS 11150 (CS-150), F5’s BIG-IP, and the Foundry ServerIron Series.

The information in this book can be understood by anyone with the slightest knowledge of networks. The basic concepts of networking needed to understand load sharing have been explained as part of the text. The best part of the text is the coherent detail with which the configuration procedure has been explained. This will definitely be one of the handiest books around for network administrators and Web administrators. It would have been useful, however, if the text had also addressed implementation and performance issues in server load balancing, such as state distribution between multiple servers, measuring of the load, method to set primary/backup, heartbeat implementations, and software load balancers in Windows 2000.