Introduction
As the Internet continues to grow exponentially, the need for network engineers to build, maintain, and troubleshoot the growing number of component networks also has increased significantly. Because network troubleshooting is a practical skill that requires on-the-job experience, it has become critical that the learning curve necessary to gain expertise in internetworking technologies be reduced to quickly fill the void of skilled network engineers needed to support the fast-growing Internet. IP routing is at the core of Internet technology, and expedient troubleshooting of IP routing failures is key to reducing network downtime. Reducing network downtime is crucial as the level of mission-critical applications carried over the Internet increases. This book gives you the detailed knowledge to troubleshoot network failures and maintain the integrity of their networks.
Troubleshooting IP Routing Protocols provides a unique approach to troubleshooting IP routing protocols by focusing on step-by-step guidelines for solving a particular routing failure scenario. The culmination of years of experience with Cisco’s TAC group, this book offers sound methodology and solutions for resolving routing problems related to BGP, OSPF, IGRP, EIGRP, IS-IS, RIP, and PIM by first providing an overview to routing and then concentrating on the troubleshooting steps that an engineer would take in resolving various routing protocol issues that arise in a network. This book offers you a full understanding of troubleshooting techniques and real-world examples to help you hone the skills needed to successfully complete the CCIE exam, as well as perform the duties expected of a CCIE-level candidate.
Who Should Read This Book?
This is an intermediate-level book that assumes that you have a general understanding of IP routing technologies and other related protocols and technologies used in building IP networks.
The primary audience for this book consists of network administrators and network operation engineers responsible for the high availability of their networks, or those who plan to become Cisco Certified Internetwork Experts.
How This Book Is Organized
Although this book could be read cover to cover, it is designed to be flexible and to allow you to easily move between chapters and sections of chapters to cover just the material that you need more work with.
• Chapter 1, “Understanding IP Routing”—This chapter provides an overview of IP routing protocols with focus on the following topics:
—Routing protocol administrative distance
The remaining chapters alternate between chapters that provides coverage of key aspects of a specific routing protocol and chapters devoted to practical, real-world troubleshooting methods for that routing protocol. The list that follows provides more detailed information:
• Chapter 2, “Understanding Routing Information Protocol (RIP)”—This chapter focuses on the key aspects of RIP needed to confidently troubleshoot RIP problems. Topics include the following:
—Split horizon with poison reverse
—Why RIP doesn’t support discontiguous networks
—Why RIP doesn’t support variable-length subnet masking (VLSM)
• Chapter 3, “Troubleshooting RIP”—This chapter provides a methodical approach to resolving common RIP problems, which include the following:
—Troubleshooting RIP route installation
—Troubleshooting RIP route advertisement
—Troubleshooting routes summarization in RIP
—Troubleshooting RIP redistribution problems
—Troubleshooting dial-on-demand routing (DDR) issues in RIP
—Troubleshooting the route-flapping problem in RIP
• Chapter 4, “Understanding Interior Gateway Routing Protocol (IGRP)”—This chapter focuses on the key aspects of IGRP needed to confidently troubleshoot IGRP problems. Topics include the following:
—Split horizon and poison reverse
—Unequal-cost load balancing in IGRP
• Chapter 5, “Troubleshooting IGRP”—This chapter provides a methodical approach to resolving common IGRP problems, which include the following:
—Troubleshooting IGRP route installation
—Troubleshooting IGRP route advertisement
—Troubleshooting IGRP redistribution problems
—Troubleshooting dial-on-demand routing (DDR) issues in IGRP
—Troubleshooting route flapping in IGRP
—Troubleshooting variance problem
• Chapter 6, “Understanding Enhanced Interior Gateway Routing Protocol (EIGRP)”—This chapter focuses on the key aspects of EIGRP needed to confidently troubleshoot EIGRP problems. Topics include the following:
—The Diffusing Update Algorithm (DUAL)
—EIGRP reliable transport protocol
—Unequal-cost load balancing in EIGRP
• Chapter 7, “Troubleshooting EIGRP”—This chapter provides a methodical approach to resolving common EIGRP problems, which include the following:
—Troubleshooting EIGRP neighbor relationships
—Troubleshooting EIGRP route advertisement
—Troubleshooting EIGRP route installation
—Troubleshooting EIGRP route flapping
—Troubleshooting EIGRP route summarization
—Troubleshooting EIGRP route redistribution
—Troubleshooting EIGRP dial backup
• Chapter 8, “Understanding Open Shortest Path First (OSPF)”—This chapter focuses on the key aspects of OSPF needed to confidently troubleshoot OSPF problems. Topics include the following:
• Chapter 9, “Troubleshooting OSPF”—This chapter provides a methodical approach to resolving common OSPF problems, which include the following:
—Troubleshooting OSPF neighbor relationships
—Troubleshooting OSPF route advertisement
—Troubleshooting OSPF route installation
—Troubleshooting redistribution problems in OSPF
—Troubleshooting route summarization in OSPF
—Troubleshooting CPUHOG problems
—Troubleshooting dial-on-demand routing (DDR) issues in OSPF
—Troubleshooting SPF calculation and route flapping
• Chapter 10, “Understanding Intermediate System-to-Intermediate System (IS-IS)”—This chapter focuses on the key aspects of IS-IS needed to confidently troubleshoot IS-IS problems. Topics include the following:
—Configuring IS-IS for IP routing
• Chapter 11, “Troubleshooting IS-IS”—This chapter provides a methodical approach to resolving common IS-IS problems, which include the following:
—Troubleshooting IS-IS adjacency problems
—Troubleshooting IS-IS routing update problems
—Case study: ISDN configuration problem
• Chapter 12, “Understanding Protocol Independent Multicast (PIM)”—This chapter focuses on the key aspects of PIM needed to confidently troubleshoot PIM problems. Topics include the following:
—Fundamentals of IGMP Version 1, IGMP Version 2, and reverse path forwarding (RPF)
• Chapter 13, “Troubleshooting PIM”—This chapter provides a methodical approach to resolving common PIM problems, which include the following:
• Chapter 14, “Understanding Border Gateway Protocol Version 4 (BGP-4)”—This chapter focuses on the key aspects of BGP needed to confidently troubleshoot BGP problems. Topics include the following:
—BGP-4 protocol specification and functionality
—Scaling IBGP networks (route reflectors and confederations)
• Chapter 15, “Troubleshooting BGP”—This chapter provides a methodical approach to resolving common BGP problems, which include the following:
—Troubleshooting BGP neighbor relationships
—Troubleshooting BGP route advertisement/origination and receiving
—Troubleshooting a BGP route not installing in a routing table
—Troubleshooting BGP when route reflectors are used
—Troubleshooting outbound traffic flow issues because of BGP policies
—Troubleshooting load-balancing scenarios in small BGP networks
—Troubleshooting inbound traffic flow issues because of BGP policies