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:

  - IP addressing concepts

  - Static and dynamic routes

  - Dynamic routing

  - Routing protocol administrative distance

  - Fast forwarding in routers

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:

  - Metrics

  - Timers

  - Split horizon

  - Split horizon with poison reverse

  - RIP-1 packet format

  - RIP behavior

  - Why RIP doesn't support discontiguous networks

  - Why RIP doesn't support variable-length subnet masking (VLSM)

  - Default routes and RIP

  - Protocol extension to RIP

  - Compatibility issues

• 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:

  - Metrics

  - Timers

  - Split horizon

  - Split horizon and poison reverse

  - IGRP packet format

  - IGRP behavior

  - Default route and IGRP

  - 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:

  - Metrics

  - EIGRP neighbor relationships

  - The Diffusing Update Algorithm (DUAL)

  - DUAL finite state machine

  - EIGRP reliable transport protocol

  - EIGRP packet format

  - EIGRP behavior

  - EIGRP summarization

  - EIGRP query process

  - Default route and EIGRP

  - 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

  - EIGRP error messages

• 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:

  - OSPF packet details

  - OSPF LSA details

  - OSPF areas

  - OSPF media types

  - OSPF adjacencies

• 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

  - Common OSPF error messages

• 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:

  - IS-IS protocol overview

  - IS-IS protocol concepts

  - IS-IS link-state database

  - 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

  - IS-IS errors

  - CLNS ping and traceroute

  - 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)

  - PIM dense mode

  - PIM sparse mode

  - IGMP and PIM packet format

• Chapter 13, "Troubleshooting PIM" ‚ This chapter provides a methodical approach to resolving common PIM problems, which include the following:

  - IGMP joins issues

  - PIM dense mode issues

  - PIM sparse mode issues

• 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

  - Neighbor relationships

  - Advertising routes

  - Synchronization

  - Receiving routes

  - Policy control

  - Scaling IBGP networks (route reflectors and confederations)

  - Best-path calculation

• 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

  - Troubleshooting BGP best-path calculation issues

  - Troubleshooting BGP filtering