IS-IS routing protocol

After explaining the concepts used by link-state "Interior Gateway Protocol" routing protocols, we will detail the IS-IS protocol with the following elements:

• the addressing scheme used by IS-IS ;

• multi-pair slicing to enable IS-IS to be used on large networks;

• the different phases used by IS-IS to enable each router in a network to determine its best paths within its network.

In addition, a few specific features and extensions to the IS-IS protocol are presented to give the reader an overview of IS-IS developments for IP networks. Finally, the last paragraph details some IS-IS engineering rules within an IP network.