This book is designed for introductory one-semester or one-year courses in communications networks in upper-level undergraduate programs. The second half of the book can be used in more advanced courses. As pre-requisites the book assumes a general knowledge of computer systems and programming, and elementary calculus. The second edition expands on the success of the first edition by updating on technological changes in networks and responding to comprehensive market feedback. Table of Contents   1 Communication Networks and Services 2 Layered Architectures 3 Digital Transmission Fundamentals 4 Circuit-Switching Networks 5 Peer-to-Peer Protocols and Data Link Layer 6 Medium Access Control Protocols and Local Area Networks 7 Packet-Switching Networks 8 TCP/IP 9 ATM Networks 10 Advanced Network Architectures 11 Security Protocols 12 Multimedia Information and Networking Appendix A Delay and Loss Performance Appendix B Network Management