The invention relates to a switch. Each port of the switch is correspondingly provided with a port control module, the port control modules form a ring network through a serial bus, and loop messages are transmitted in the ring network. The loop messages comprise a plurality of message units corresponding to the ports, and each message unit comprises a source address portion, a target address portion and a data portion. Each port control module, through identifying the source address portions or the target address portions in the loop messages, is used for loading data to the data portions of the corresponding message units or reading the data of the data portions of the corresponding message units. Since the switch transmits the messages by use of the serial ring network, the problem of inconsistency of query time of target ports, caused by a mapping table is avoided, the transmission delay of each port is enabled to be consistent, and the real-time performance of the switch is enabled to be improved.