Normally, routes are propagated regardless of the existence of a different path. The BGP conditional advertisement feature allows a route not to be advertised based on existence or non-existence of other routes. With this new feature, a child table under bgp.neighbor is introduced. Any route matched by one of the route-map specified in the table will be advertised to the peer based on the corresponding condition route-map.

You can enable and disable conditional advertisements using the CLI.