a method for communication link for an access network device . the access network device comprises : a node server , an access switch , and a terminal . the method comprises : the node server requesting for a protocol packet on the basis of a service initiated by the source terminal ; acquiring a piece of communication link information of the current service , and the communication link information comprises a piece of communication port information for the node server and the access switch involved in the current service ; on the basis of the communication port information for the node server , the node server setting up within an internal data packet address table the port directed by the data packet of the current service ; on the basis of the communication port information for the access switch , transmitting to the corresponding accessing switch a port configuration command ; on the basis of the port configuration command , the accessing switch setting up the port directed by the data packet of the current service within an internal data packet address table . by means of the present invention , the stability of a transmission channel is ensured , thereby avoiding delays for multimedia services .