An improved autonegotiation approach includes determining that a negotiated rate between a first network device and a second network device exceeds data transfer capacity over a network path downstream of the second network device. In response, a configuration message is generated and transmitted to the first network device. When received by the first network device, the configuration message causes the first network device to limit data transfer between the first network device and the second network device to no more than the downstream data transfer capacity.

Embodiments of the present disclosure provide a data transmission method and a device, and the method includes: determining synchronization header indication information indicating a frame header location of a first code stream, where the first code stream is obtained by encoding CPRI service data; decoding the first code stream to obtain a second code stream, where the first code stream is a 10B code stream, and the second code stream is an 8B code stream, or the first code stream is a 66B code stream, and the second code stream is a 64B code stream; inserting frame header indication information indicating a frame header location of the second code stream into the second code stream according to the synchronization header indication information; and mapping the second code stream and the frame header indication information into an OPU in an ODU frame.

A method of processing a digital signal for transmission is provided comprising digital data frames, by compressing the digital data frames; and generating an optical data unit for transmission comprising multiple of the compressed digital data frames. The optical data unit is configured for transport by an Optical Transport Network, OTN.