Administrator Guide

Intermediate System to Intermediate

System

Dell Networking OS supports intermediate system to intermediate system (IS-IS).

• The IS-IS protocol is an interior gateway protocol (IGP) that uses a shortest-path-first algorithm. Dell

Networking supports both IPv4 and IPv6 versions of IS-IS.

• The IS-IS protocol standards are listed in the Standards Compliance chapter.

Topics:

• IS-IS Protocol Overview

• IS-IS Addressing

• Multi-Topology IS-IS

• Graceful Restart

• Implementation Information

• Configuration Information

• IS-IS Metric Styles

• Configure Metric Values

• Sample Configurations

IS-IS Protocol Overview

The IS-IS protocol, developed by the International Organization for Standardization (ISO), is an interior

gateway protocol (IGP) that uses a shortest-path-first algorithm.

NOTE: This protocol supports routers passing both IP and OSI traffic, though the Dell Networking

implementation supports only IP traffic.

IS-IS uses the following management information base (MIB): draft-ietf-isis-wg-mib-16 and f10-

isis.

IS-IS is organized hierarchically 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 systems manage

destination paths for external routers. Only Level 2 routers can exchange data packets or routing information

directly with external routers located outside of the routing domains. Level 1-2 systems manage both inter-

area and intra-area traffic by maintaining two separate link databases; one for Level 1 routes and one for Level

2 routes. A Level 1-2 router does not advertise Level 2 routes to a Level 1 router.

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