An exploration of data networks, evolving integrated networks, and the various analysis and design tools. Table of Contents 1. Introduction and Layered Network Architecture. 2. Point to Point Protocols and Channels. 3. Delay Models in Data Networks. 4. Multiaccess Communication. 5. Routing in Data Networks. 6. Flow Control. Appendix A: Review of Markov Chain Theory. Appendix B: Summary of Results.