Route Summarization

Keeping routing tables small helps conserve memory and can improve the time required by a router to forward packets. Route summarization allows an engineer to keep the routing tables more manageable, without limiting reachability. Instead of advertising routes for every subnet, a router advertises a single route that encompasses multiple subnets. Each router can forward packets to the same set of destinations, but the routing table is smaller. For example, instead of advertising routes 10.11.0.0/24, 10.11.1.0/24, 10.11.2.0/24, and so on—all subnets up through 10.11.255.0/24—a router could advertise a single route for 10.11.0.0/16, which includes the exact same range of addresses.

Route summarization works best when the subnet ...

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