Patent ID: 7590749

Claim:
A network access device, which is connected to a plurality of user terminals via a user interface, the network access device comprising: a user multicast information storing table for storing a multicast address and user identification information of the user interface; and an IGMP protocol processing unit configured to obtain the user identification information from a user IGMP message by the network access device, retrieving the user multicast information after access control checking and adding a corresponding item containing the multicast address and the user identification information to the user multicast information storing table if the user is new to the multicast group which he makes request for entering when said user IGMP message is a Join message, deleting the item of the multicast group corresponding to the user identification information from the user multicast information table, entering a GSQ process and waiting for a next IGMP message when said user IGMP message is a Leave message, wherein said user multicast information storing table stores information indicating the current operation state of each multicast group.