This chapter covers the following topics:
Understanding Redistribution Fundamentals—Describes reasons why multiple protocols may exist within an organization and introduces the basics of redistribution.
Understanding the Routing Decisions that Affect Redistribution—Describes routing metrics, path selection, and potential problems associated with redistribution.
Controlling Routing Updates During Redistribution—Describes the methods to control the routing information sent between routers during redistribution.
Configuring Redistribution—Describes the steps involved in setting up redistribution.
Controlling Routing Updates with Filtering—Describes the use of distribute lists.
Verifying, Maintaining, and Troubleshooting the Redistribution and Filtering Implementation—Focuses on the traceroute and extended ping commands.
The topics in this chapter deal with the traffic generated by routing updates in terms of both the network resources that they use and the information contained within them. The chapter covers two different but related areas, redistribution and filtering. The network overhead involved in routing updates has already been dealt with in other chapters; it keeps recurring as a theme because all network traffic directly influences the network's capability to scale or to grow.
The information propagated through the network is complex when dealing with one routing protocol. When multiple protocols have to share information (through redistribution) so that the larger network can see every route available within the autonomous system (AS), the information flow must be controlled and closely managed with filtering and other solutions.
This chapter deals with the need for redistribution, which increases the network overhead, and filtering, which is used to reduce overhead. The chapter first explains the design issues that might affect the configuration, and then provides configuration examples of route redistribution and filtering.
The purpose of the "Do I Know This Already?" quiz is to help you decide what parts of this chapter to use. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now.
The 16-question quiz, derived from the major sections in the "Foundation Topics" portion of the chapter, helps you determine how to spend your limited study time.
Table 11-1 outlines the major topics discussed in this chapter and the "Do I Know This Already?" quiz questions that correspond to those topics.
|Foundation Topics Section||Questions Covered in This Section||Score|
|Understanding Redistribution Fundamentals||1–3|
|Understanding the Routing Decisions That Affect Redistribution||4–7|
|Controlling Routing Updates During Redistribution||8–9|
|Controlling Routing Updates with Filtering||12–14|
|Verifying, Maintaining, and Troubleshooting the Redistribution and Filtering Implementation||15–16|
The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you do not know the answer to a question or are only partially sure of the answer, you should mark this question wrong for purposes of the self-assessment. Giving yourself credit for an answer you correctly guess skews your self-assessment results and might provide you with a false sense of security.
|1.||Which of the following are reasons to run multiple routing protocols?
|2.||EIGRP automatically redistributes into which routing protocols?
|3.||How many IP routing tables can be held on a router within a typical organization?
|4.||The problems experienced as a result of multiple routing processes and their redistribution include which of the following?
|5.||Which command is used to configure the administrative distance?
|6.||What action is taken if no seed or default metric is configured for OSPF when redistributing EIGRP?
|7.||What techniques can be employed to avoid redistribution problems?
|8.||Which of the following may be necessary to control the routing updates?
|9.||Which of the following is a complex access list that permits conditional programming?
|10.||Which command is used to establish the default or seed metric for EIGRP?
|11.||What is the default metric type value for routes redistributed into OSPF?
|12.||What is the purpose of distribute lists?
|13.||Where are distribute lists defined?
|14.||All the following statements are true; which of the following actions is taken first?
|15.||Which commands could be used to verify and troubleshoot a network that is redistributed?
|16.||Which of the following commands is not useful for tracking redistribution problems?
The answers to this quiz are found in Appendix A, "Answers to Chapter 'Do I Know This Already?' Quizzes and Q&A Sections." The suggested choices for your next step are as follows: