Chapter 10. Configuring Integrated IS-IS

This chapter covers the following topics:

  • Basic Configuration of Integrated IS-IS—Covers essential commands for configuring IS-IS.

  • Optional Integrated IS-IS Commands—Describes optional commands; however, note that many of these commands are commonly used to tune the required setup.

  • Verifying the Integrated IS-IS Operation—Looks at show commands that verify the setup.

  • Troubleshooting the Integrated IS-IS Operation—Describes show and debug commands that you can use to diagnose problems.

The first section of this chapter deals with the commands required to create an IS-IS routing environment. Subsequent sections cover optional commands and troubleshooting. The topics in this chapter detail the steps to configuring the IS-IS protocol for integrated routing on a Cisco network. This chapter assumes knowledge of routing protocols—in particular, link-state routing protocols—and the terminology, concepts, and operation of IS-IS.

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 12-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 10-1 outlines the major topics discussed in this chapter and the "Do I Know This Already?" quiz questions that correspond to those topics.

Table 10-1. "Do I Know This Already?" Foundation Topics Section-to-Question Mapping
Foundation Topics SectionQuestions Covered in This SectionScore
Basic Configuration of Integrated IS-IS1–3 
Optional Integrated IS-IS Commands4–6 
Verifying the Integrated IS-IS Operation7–10 
Troubleshooting the Integrated IS-IS Operation11–12 
Total Score  


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 is the correct command to start the Integrated IS-IS routing process?
  1. ip router isis

  2. router isis

  3. routing ip isis

  4. router clns

2.Where is the Integrated IS-IS routing process started?
  1. At the exec level

  2. At the interface level

  3. At both the exec and interface levels

  4. Underneath the IP routing process

3.What is the purpose of the net command?
  1. To define the summarized address range on the router interface

  2. To define the area into which the interface is to be placed

  3. To define the IS-IS address on the interface

  4. To define the CLNS address for the router

4.Where is the routing level changed from the default of Level 1-2?
  1. At the exec level

  2. At the interface level

  3. Underneath the routing process or at the interface level

  4. Underneath the IP routing process

5.Which of the following are valid commands for changing the routing level?
  1. isis level-2

  2. isis circuit-type level-1

  3. isis router level-1

  4. ip router level 1

6.Which of the following commands summarizes the subnets to at the area boundary?
  1. summary-address

  2. summary-address

  3. ip isis summary address

  4. None of these options are correct; summarization is supported only in OSPF and EIGRP

7.Which of the following are displayed in the command show clns neighbor?
  1. The contents of the neighbor table.

  2. The routing level as defined at the interface level.

  3. The System ID of the transmitting neighbor.

  4. All answers provided are correct.

8.Which of the following are displayed in the command show clns interface?
  1. The number of LSPs received on the interface

  2. The parity check on the received hellos

  3. The metric of the outgoing interface

  4. The round trip delay

9.Which of the following are displayed in the command show isis database?
  1. The root of the SPF tree

  2. The LSPs in the local database

  3. Whether an LSP has been fragmented

  4. The sequence number of the LSPs

10.Which of the following commands shows whether the ATT bit has been set?
  1. show isis hello packets

  2. show isis database

  3. debug isis interface

  4. debug clns interface

11.Which of the following are displayed in the command debug isis update-packets?
  1. Hellos

  2. LSPs

  3. CSNPs

  4. PSNPs

12.Which of the following are displayed in the command debug isis adjacency-packets?
  1. The population of the PATH database

  2. The LSPs

  3. Changes in the state of the adjacencies

  4. Hello packets

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:

  • 7 or less overall score—Read the entire chapter. This includes the "Foundation Topics," "Foundation Summary," "Q&A," and "Scenarios" sections.

  • 8–9 overall score—Begin with the "Foundation Summary" section, and then go to the "Q&A" and "Scenarios" sections at the end of the chapter. If you have trouble with these exercises, read the appropriate sections in "Foundation Topics."

  • 10–12 overall score—If you want more review on these topics, skip to the "Foundation Summary" section, and then go to the "Q&A" and the "Scenarios" sections at the end of the chapter. Otherwise, move to the next chapter.