1-3. aggregate-address address mask as-set advertise-map route-map-name
address— Aggregate IP address.
mask— Aggregate mask.
route-map-name— Route map used to determine the prefixes used to form the aggregate.
Purpose: To create an aggregate entry in the BGP table. An aggregate is created only if a more-specific route of the aggregate exists in the BGP table. Without the as-set option, the AS path information for the specific routes forming the aggregate is lost. This form of the aggregate-address command advertises the aggregate while retaining the AS path information for the more-specific routes. An advertise-map can be used to determine which AS path information is retained in the aggregate.
Cisco IOS Software Release: 10.0 ...