The routers provide a feature related to exchange of control information between DSLAM and BRAS (BSA is described in this model). This exchange of information is implemented by in-band control connection between DSLAM and BSA, also referred to as ANCP connection.
In case of dual homing, two separate connections are set. As a consequence, there is no need to provide synchronization of ANCP state. Instead every node of the redundant-pair obtains this information from the DSLAM and creates corresponding an ANCP state independently.