This chapter covers the following topics:
BGP Attributes—Describes the BGP attributes used for determining BGP behavior.
Controlling BGP Path Selection—Describes explains how to configure BGP attributes on Cisco routers.
Verifying the Configuration of Attributes—Describes Cisco IOS commands to display output related to BGP attributes.
The topics in this chapter describe the values and process used in BGP path selection and build on the basic configuration of BGP described in the previous chapter. In this discussion of advanced BGP topics, explanation of the technology is coupled with configuration examples so that your conceptual understanding of BGP is reinforced by concrete implementation examples.
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 14-question quiz, derived from the major sections in the "" portion of the chapter, helps you determine how to spend your limited study time.
Table 16-1 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|
|Controlling BGP Path Selection||6–12|
|Verifying the Configuration of Attributes||13–14|
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.||Well-known mandatory attributes are described as which of the following?
|2.||Optional nontransitive attributes are described as which of the following?
|3.||Which BGP attributes are used in BGP path selection?
|4.||A route has an AS-Path of 7 25 19 69. What can you learn from reading this path?
|5.||Place the following attributes in the order that BGP evaluates them to select a best path: AS-Path, Local Preference, MED, Weight.
|6.||Give the command that would change the weight attribute for the path to the peer 126.96.36.199.
|7.||Which of the following statements are true about the BGP weight attribute?
|8.||Which of the following statements about the BGP local-preference attribute are true?
|9.||Which of the following statements describes MED?
|10.||Consider the following route map. What will be the local-preference for 192.168.26.0/24?
access-list 39 permit 192.168.24.0 0.0.3.255 access-list 32 permit 192.168.26.0 0.0.0.255 route-map test permit 10 match ip address 39 match ip address 32 set ip local preference 150 route-map test permit 20 match ip address 39 32 set ip local preference 200
|11.||Consider the route map from the previous question. What will be the local-preference for 192.168.25.0/24?
|12.||Consider the route map from the previous question. What will be the local-preference for 192.168.20.0/24?
|13.||In the command show ip bgp, the "i" origin code is placed at the end of a line in the BGP table. It can be which of the following values?
|14.||Which command shows the local preference and weight attribute values?
The answers to the "Do I Know This Already?" 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: