According to one embodiment, a receiving unit receives a frame from a first external communication device connected to a first communication port. First and second databases store destination determination information used to determine a second communication port to which a second external communication device is connected. A determination unit determines the second communication port by accessing destination determination information in the first database when the received frame is a first frame, and determines the second communication port by accessing destination determination information in the second database when the received frame is a second frame. The first database is accessible to the destination determination information at a higher speed than the second database.