Reference Guide

Intermediate System to Intermediate System | 421

Intermediate System to Intermediate System

Intermediate System to Intermediate System is supported on platforms e z

IS-IS is supported on the E-Series ExaScale platform with FTOS 8.1.1.0 and later. It is supported on the

with FTOS 8.3.10.0. It is supported on the Z9000 platform with FTOS 9.0.0.0.

Intermediate System to Intermediate System (IS-IS) protocol is an interior gateway protocol (IGP) that

uses a shortest-path-first algorithm. Dell Force10 supports both IPv4 and IPv6 versions of IS-IS, as it is

detailed in this chapter.

• Protocol Overview on page 421

• IS-IS Addressing on page 422

• Multi-Topology IS-IS on page 423

• Graceful Restart on page 424

• Implementation Information on page 425

• Configuration Information on page 426

• IS-IS Metric Styles on page 445

• Sample Configuration on page 449

IS-IS protocol standards are listed in the Chapter 49, Standards Compliance chapter.

Protocol Overview

The intermediate-system-to-intermediate-system (IS-IS) protocol, developed by the International

Organization for Standardization (ISO), is an interior gateway protocol (IGP) that uses a shortest-path-first

algorithm.

IS-IS is organized hierarchally into routing domains, and each router or system resides in at least one area.

In IS-IS, routers are designated as Level 1, Level 2 or Level 1-2 systems. Level 1 routers only route traffic

within an area, while Level 2 routers route traffic between areas. At its most basic, Level 1 systems route

traffic within the area and any traffic destined for outside the area is sent to a Level 1-2 system. Level 2

Note: This protocol supports routers passing both IP and OSI traffic, though the Dell Force10

implementation supports only IP traffic.