Stated goal by Cisco Router Configuration: A Practical Introduction to Cisco IOS configuration is to make Cisco Internetworking Operating System (IOS) easy for the uninitiated. And with good reason, as the three wrote this book as an employee of an international Internet service provider, Digital Island - itself an all-Cisco shop, from router to switch and the load-balancing device - and former employees of Cisco Systems. Although this book begins with the usual description of the OSI model and types of devices, things quickly get more interesting as fiction ZIP Corporation and its globetrotting network are introduced. (ZIP's network serves as a basis for discussion and illustration.) In the proof of knowledge and skills, Leinwand and company are incredible thorough in their explanations, yet resist the temptation to overwhelm with too much detail.