Apparatus and methods for asynchronous clock mapping are provided herein. In certain configurations, an upstream server of a transport network generates clock difference data indicating a time difference between a server clock signal and a client clock signal, which have an asynchronous timing relationship with respect to one another. The clock difference data is generated with high precision by using one or more time-to-digital converters (TDCs). The clock difference data is included in a transmitted data stream, and is used by a downstream server to recover client information with enhanced accuracy.