Reference Guide

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Intermediate System to Intermediate System

(IS-IS)

Overview

Intermediate System to Intermediate System Protocol (IS-IS) for IPv4 and IPv6 is supported on the

S-Series platform, as indicated by the character under each command heading, on the S4810 (indicated

by , and Z9000 (indicated by the z character).

IS-IS is an interior gateway protocol that uses a shortest-path-first algorithm. IS-IS facilitates the

communication between open systems, supporting routers passing both IP and OSI traffic.

A router is considered an intermediate system. Networks are partitioned into manageable routing

domains, called areas. Intermediate systems send, receive, and forward packets to other routers within

their area (Level 1 and Level 1-2 devices). Only Level 1-2 and Level 2 devices communicate with

other areas.

IS-IS protocol standards are listed in the Standard Compliance chapter in the FTOS Configuration

Guide.

Commands

The following are the FTOS commands to enable IS-IS.

• adjacency-check

• advertise

• area-password

• clear config

• clear isis

• clns host

• debug isis

• debug isis adj-packets

• debug isis local-updates

• debug isis snp-packets

• debug isis spf-triggers

S6000

Note: The fundamental mechanisms of IS-IS are the same between IPv4 and IPv6. Where there are differences

between the two versions, they are identified and clarified in this chapter. Except where identified, the information in

this chapter applies to both protocol versions.