Chapter 4: IS-IS Configuration and Testing

Jncip Lab skills covered in this chapter:

• Multi-Level IS-IS configuration

  • Default route origination

• Network types

• Authentication

  • Hello and LSP authentication

• IS-IS policy

  • Summarization, filtering, and route leaking

  • Route Redistribution

• Metrics, timers, and various other "knobs"

This chapter details various JNCIP-level IS-IS configuration scenarios, and provides examples of the verification methods that can be used to confirm proper IS-IS protocol operation. It is assumed that your configurations are currently based on the case study criteria presented at the end of the initial system and interface configuration chapters. You will now be adding the ISIS protocol to this test bed. If you are unsure as to the state of your routers, you should compare your configuration against those provided at the end of Chapters 1 and 2, and verify that all of your router interfaces are operational before proceeding.

As described in the previous chapter, the proper operation of your IGP will play a critical role in the overall success of your JNCIP lab attempt. Serious problems with your IGP’s operation will almost guarantee that you will experience malfunctions with higher-level protocols and services like BGP or RSVP signaling, and the cascading effects of the cumulative point loss that will occur in such situations will virtually assure that you will experience little joy at the end of your testing day. A successful JNCIP exam candidate must possess the practical skills and protocol knowledge necessary to proficiently configure and troubleshoot the IS-IS protocol in a variety of network scenarios as demonstrated in this chapter.

Because the overall purpose of OSPF and IS-IS are essentially identical, this chapter will demonstrate IS-IS configuration and testing using topologies and configuration requirements that parallel the examples used in the previous chapter wherever possible. The fact that IS-IS supports only the point-to-point and broadcast network types means that you will be mercifully spared the need to configure multipoint and NBMA network types.

This chapter concludes with a case study that is designed to approximate a typical JNCIP ISIS configuration scenario. The results of key operational mode commands are provided in the case study analysis section so that you can also compare the behavior of your network to a known good example. Router configurations that meet all case study requirements are provided at the end of the case study for comparison with your own configurations.