EIGRP for IP: Basic Operation and Configuration
Alvaro Retana, Don Slice, Russ White · CERN Document Server (European Organization for Nuclear Research) · 2000
From the Book: PREFACE: Cisco Systems designed EIGRP (Enhanced Interior Gateway Routing Protocol) to support the Internet Protocol (IP), Novell's IPX, and Apple's AppleTalk protocols. EIGRP is used in networks of all sizes, including many large corporate networks, across the world. Routers direct trafficuser data in the form of packetsthrough the network toward its destination. Routing protocols provide the road signs for the routers to use to decide where to forward the traffic to next on the path to the destination. EIGRP is designed to provide routing knowledge within a single domainor between routers controlled and maintained by the same group of people. A domain is usually understood as containing all the routers owned and operated by a single administration, such as a company or a department. Although EIGRP can provide routing information for various protocols, we have limited the scope of this book to just IP. The primary reason for this decision is to maintain focus and clarity. Most of the theory and the design principles you learn here can be applied to networks using EIGRP to route protocols other than IP. This book has been designed to provide a quick but complete description of EIGRP and its use. Throughout our experience, working firsthand on the design and troubleshooting of EIGRP networks, we have found that the protocol is typically not well understood or documented. Although EIGRP is very easy to configure, the lack of educational resources explaining how EIGRP functions has led to nonoptimized networks and has caused issues to chronically pop up in many of them. Our intent is topartiallyfill the documentation gap with this guide while also providing design and troubleshooting guidelines to the most common scenarios and problems. The intended audience includes people with some networking experience and at least a basic understanding of routing protocols. Chapter 1 begins with EIGRP theory, explaining the basic concepts, terminology, and mechanisms EIGRP uses to provide routing information. Chapter 2 takes a brief look at the most important configuration options with EIGRP. Chapter 3 considers network design principles within the framework of EIGRP's capabilities and includes tips on basic network architecture and specific studies on situations you may find in an EIGRP network. Finally, Chapter 4 provides information on troubleshooting various conditions you may find within a network running EIGRP. Problems ranging from errors building neighbor relationships to troubleshooting Stuck in Active (SIA) routes are covered in this chapter. In this book, key terms appear in boldface type the first time they are used. These terms are defined in the glossary at the end of the book, following Chapter 4.