IS-IS Overview

The Intermediate System-to-Intermediate System (IS-IS) protocol is a classless interior routing protocol developed by the International Organization for Standardization (ISO) as part of the development of the Open Systems Interconnection (OSI) protocol suite. Like OSPF routing, IS-IS uses hello packets that allow network convergence to occur quickly when network changes are detected.

This overview contains the following topics:

• IS-IS Areas
• Network Entity Titles and System Identifiers
• IS-IS Path Selection
• Protocol Data Units