A method includes: sending, by a first device, a first bit stream to a second device, where the first bit stream is sent over N logical lanes of a physical layer of the first device; sending, by the first device, a first trigger marker group to the second device, where the first trigger marker group is used to indicate that the sending of the first bit stream ends; and sending, by the first device, a second bit stream to the second device in response to the sending of the first trigger marker group, where the second bit stream is sent over P logical lanes of the physical layer of the first device, and both N and P are positive integers.