An example exchange method includes: receiving, through a first interface, M bits; after receiving the M bits, receiving M bytes through the first interface, wherein each of the M bits indicates a status of a corresponding byte in the M bytes; encapsulating, based on the M bits corresponding to the M bytes, L bytes of the M bytes to obtain L encapsulated bytes, wherein M and L are integers greater than or equal to 1, and L is less than M; exchanging the L encapsulated bytes to a second interface; decapsulating the L encapsulated bytes to obtain L decapsulated bytes; and sending the L decapsulated bytes through the second interface.