Aggregate the Routes to Advertise to BGP4 Neighbors

You can aggregate BGP4 routes into one network prefix, for example, 10.1.1.1/32. This single prefix is advertised to BGP4 neighbors instead of the individual BGP routes in the routing table that are within the specified range.
  1. Access global configuration mode.
    device# configure terminal
  2. Access BGP configuration mode.
    device(config)# router bgp
  3. Access BGP address family IPv4 unicast configuration mode.
    device(config-bgp-router)# address-family ipv4 unicast
  4. Specify the network prefix into which routes are to be aggregated.
    device(config-bgp-ipv4u)# aggregate-address 10.1.1.1/32

The following example summarizes the commands in this procedure.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# address-family ipv4 unicast
device(config-bgp-ipv4u)# aggregate-address 10.1.1.1/32