Understanding Level 1 and Level 2 Routing
In level 1, IS nodes are based on the ID portion of the address. All level 1 routers route within their own area. They recognize the destination within their area by reading the destination address. If the destination is within the same area, the packet is routed to the destination. If the destination is not within the same area, it is sent to the closest level 2 router.
In IS-IS, all level 1 areas are stub areas, so no information is sent to level 1 routers that are outside their areas. All routers within the level 1 area maintain identical databases. A level 1 router will have the area portion of its address manually configured. It will not create neighbors with a node whose area addresses do not ...
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