For courses in professional level Cisco certification and intermediate level networking. This book focuses on using Cisco routers connected in LANs and WANs typically found at medium-to-large network sites. The student will study a broad range of technical details on topics related to routing, including routing principles, IP addressing issues such as variable-length subnet masks (VLSMs), route summarization, and protocol redistribution. The routing protocols Open Shortest Path First (OSPF), Enhanced Interior Gateway Routing Protocol (EIGRP), and Border Gateway Protocol (BGP) are investigated in detail. Configuration examples and sample verification output demonstrate troubleshooting techniques, and a case study is used throughout the book to review key concepts and to discuss critical issues surrounding network operation. Chapter-ending configuration exercises and review questions illustrate and help solidify the concepts presented in the book.