Book excerpt: This book is a practical guide to IPv6 addressing Unix and network administrators with experience in TCP/IP(v4) but not necessarily any IPv6 knowledge. It focuses on reliable and efficient operation of IPv6 implementations available today rather than on protocol specifications. Consequently, it covers the essential concepts, using instructive and thoroughly tested examples, on how to configure, administrate, and debug IPv6 setups. These foundations are complemented by discussions of best practices and strategic considerations aimed at overall efficiency, reliability, maintainability, and interoperation.