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Intermediate System to Intermediate System
Intermediate System to Intermediate System is supported on platform: e
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
described in this chapter.
• Protocol Overview on page 507
• IS-IS Addressing on page 508
• Multi-Topology IS-IS on page 509
• Graceful Restart on page 510
• Implementation Information on page 511
• Configuration Information on page 512
• IS-IS Metric Styles on page 531
• Sample Configuration on page 535
IS-IS protocol standards are listed in the Appendix 63, 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
systems manage destination paths for external routers. Only Level 2 routers can exchange data packets or
Note: This protocol supports routers passing both IP and OSI traffic, though the Dell Force10
implementation supports only IP traffic.