US Patent 9794194 Relay system and switching device

A MCLAG table retains a first port in association with a first identifier. A port control unit controls a first port group to a transmission/reception permitted state when the first port group is set to active, and controls the first port group to a transmission/reception prohibited state when the first port group is set to standby. A relay processing unit relays a frame containing the first identifier as a destination port to the first port group when the first port group is controlled to the transmission/reception permitted state and relays the same to a bridge port when the first port group is controlled to the transmission/reception prohibited state. When the first port group is controlled to the transmission/reception prohibited state, a transmission stop instructing unit instructs a peer device to stop frame transmission to the first port group.