CIDR Notation - Prefix Aggregation

Prefix Aggregation

CIDR provides the possibility of fine-grained routing prefix aggregation. For example, sixteen contiguous /24 networks can be aggregated and advertised to a larger network as a single /20 route, if the first 20 bits of their network addresses match. Two aligned contiguous /20 blocks may be aggregated to a /19, and so forth. This results in reduction of the number of routes that have to be advertised.