Fetches a list of BGP speakers hosted by Dynamic Routing agent.

def list_bgp_speaker_on_dragent(self, bgp_dragent, **_params):
        """Fetches a list of BGP speakers hosted by Dynamic Routing agent."""
        return self.get((self.agent_path + self.BGP_DRINSTANCES)
                        % bgp_dragent, params=_params)