Chapter 7. Intermediate System-to-Intermediate System—Better, Stronger, Faster, and Scarier

What You Will Learn

After reading this chapter, you should be able to

  • Explain the Intermediate System-to-Intermediate System (IS-IS) routing protocol

  • Understand the concepts, terminology, and operation of IS-IS

  • Compare IS-IS with OSPF

  • Understand the basics of configuring IS-IS on Cisco routers

IS-IS is a hierarchical link-state interior routing protocol similar to OSPF. The International Organization for Standardization (ISO) originally developed IS-IS to route packets using Network Service Access Point (NSAP) addresses, and not IP addresses.

Comparing IS-IS and IP Networks

In the IP world, the two main entities are hosts and routers. (See Figure 7-1.) An IP protocol ...

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