3.5 Resources for Junos OS BGP Migrations

This section discusses specific Junos OS details and behavior to assist in migrations. Advertising an inactive route due to protocol preferences, AS identification, and allowing for controlled AS loops are discussed next.

3.5.1 Advertisement of inactive BGP routes

Some migration scenarios can result in a prefix being present in the routing table both as an IGP route and a BGP route. Default or manipulated protocol preferences in Junos OS may activate the IGP route, stopping propagation of the BGP version that contains BGP attributes. The advertise-inactive configuration knob assists in this scenario, allowing for a non-active BGP route to be advertised into BGP. This knob applies only for the case in which the reason for not advertising the BGP route is the existence of the same route from another protocol.