BGP does not propagate or advertise private IP addresses or routes in the global Internet routing table. Private IP addresses, as defined in RFC 1918, are used within private networks and are not routable on the public Internet. BGP treats private routes as internal routes and does not allow them to be advertised outside of the private network. However, BGP can be used to exchange routes between different private networks using a technique called BGP peering or BGP VPN. In this case, the private routes are encapsulated inside BGP messages and are only visible to the peered networks.
