Disabling Suppression of Route Advertisements

Routes received from a neighboring AS are not advertised back by default. BGP checks whether the neighboring AS matches the AS of the external peer to which the router is advertising. If there is a match, the route advertisement is suppressed. Advertisement suppression is enabled by default for BGP peers configured in non-VPN routing and forwarding (VRF) instances, including the master instance. To disable the default advertisement suppression, including the advertise-peer-as statement:

advertise-peer-as;

If you include the advertise-peer-as statement in the configuration, BGP advertises the route regardless of this check.

To restore the default behavior, include the no-advertise-peer-as statement in the configuration.:

no-advertise-peer-as; 

For a list of hierarchy levels at which you can configure these statements, see the statement summary section for this statement.