Abstract: The present disclosure provides a time synchronization method, including: acquiring, by a slave device, a first optical fiber transmission delay from a master device to the slave device, and a second optical fiber transmission delay from the slave device to the master device; exchanging a time synchronization signal with the master device, and calculating an initial time offset; adjusting the initial time offset by using the first optical fiber transmission delay and the second optical fiber transmission delay to obtain a corrected time offset; and adjusting a local clock according to the corrected time offset. Embodiments of the present disclosure further provide a corresponding device and system.

Abstract: A method for transmitting a packet. The method includes: receiving an upstream packet carrying an original user identifier of a user; establishing a corresponding relationship between user related information on the user and a replacement user identifier in accordance with the upstream packet carrying the original user identifier of the user, and sending an upstream packet carrying the replacement user identifier of the user to a server, the replacement user identifier being capable of distinguishing the user from others; determining the user related information corresponding to the replacement user identifier in the downstream packet in accordance with the corresponding relationship, and transmitting the downstream packet in accordance with the user related information.