A communication system, wireless LAN base station controller, and a wireless LAN base station device for efficiently communicating a broadcast frame or multicast frame through a downstream channel. The communication system (10) comprises an AP controller (100) and a wireless LAN base station device (200). A frame converting section (102) of the AP controller (100) performs conversion into a 802.11 frame according to the network-side tunnel header of the downstream broadcast or multicast frame, and a tunnel creating/managing section (103) creates a tunnel header having a destination MAC address which is a broadcast or multicast address, and encapsulates the 802.11 frame by the tunnel header. A tunnel creating/managing section (202) of the wireless LAN base station device (200) adds the BSSID of the wireless LAN base station device (200) to the header of the 802.11 frame from which the tunnel header is removed, and terminal-side input/output section (204) sends the 802.11 frame with the BSSID.