Data Networking is a capability that allows users to combine separate data bases, telecommunication systems, and specialised computer operations into a single integrated system, so that data communication can be handled as easily as voice messages. Data communications is the problem of getting information from one place to another reliably (secure both from channel disruptions and deliberate interference) while conforming to user requirements. IP (Internet protocol) is the central pillar of the Internet and was designed primarily for internetworking as being a simple protocol almost any network could carry. The business world appears to increasingly revolve around data communications and the Internet and all modern data networks are based around either the Internet or at least around IP (Internet Protocol)-based networks. However, many people still remain baffled by multiprotocol networks - how do all the protocols fit together? How do I build a network? What sort of problems should I expect? This volume is intended not only for network designers and practitioners, who for too long have been baffled by the complex jargon of data networks, but also for the newcomer - eager to put the plethora of "protocols" into context. After the initial boom the rate of IP development is now beginning to stabilise, making a standard textbook and reference book worthwhile with a longer shelf life. Highly illustrated and written in an accessible style this book is intended to provide a complete foundation textbook and reference of modern IP-based data networking - avoiding explanation of defunct principles that litter other books. Network/IP engineers, Network operators, engineering managers and senior undergraduate students will all find this invaluable.