RouteAggregation refers to the collection of "adjacent" routes together, in order to shorten the routing tables. It is made possible with ClasslessInterDomainRouting (CIDR).

If you have enough adjacent routes to use a higher prefix, you can use RouteAggregation. For example, if your network has

On different subnets internally, you can advertise the whole lot by using A /23 prefix has one less bits than a /24, which is 2 networks - so the 2 adjacent /24 networks starting from can be thought of as a single /23

Essentially any CIDR prefix can be thought of as the aggregation of all longer prefixes under it: is the aggregation of the 256 192.168.x.0/24 addresses

A /24 prefix is the aggregation of the 4 /25 prefixes under it

See for a CIDR subnet calculator

Part of CategoryNetworking