IS-IS

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Link State

• Dijkstra SPF Algorithm
• "default" metric on interfaces (0...63)
• Backbone Level (not area)
• OSI Address: Area ID (value starting with 49 means private address) + System ID (6) + NSEL (1; default value is 00)
• Databases: Level 1 = Intra-Area Routes; Level 2 = Backbone Routes

Configuration

Base

config# router sis
config-router# net 49.0001.3333.3333.3333.00
config# interface s0/0
config-if# ip router isis

Levels

config-router# is-type [level-1|level-1-2|level-2-only]

Levels Per Interface with Metrics

config-if# isis circuit-type [level-1|level-1-2|level-2-only]
config-if# isis metric 10 (0...63; 10 is the default)

Route Summaries

config-router# summary-address 172.16.0.0 255.255.0.0 [level-1|level-1-2|level-2-only]

Redistribution Tip

Use a route map to specify only the interfaces running ISIS that are to be distributed using the "redistribute connected" command