A method for scheduling a data message in a Passive Optical Network, PON, and Ethernet Over Cable, EOC networking, characterized by comprising: allocating, by an Optical Coax Unit, OCU, one or more coaxial side Logical Link Identifiers, LLIDs, for one or more Coaxial Network Units, CNUs, having accessed the OCU, and acquiring one or more optical network side LLIDs allocated for the OCU by an Optical Line Terminal, OLT; and establishing a mapping relationship between the coaxial side LLIDs and the optical network side LLIDs, and scheduling a data message of one of the CNUs according to the mapping relationship; wherein the step of allocating, by the OCU, the one or more coaxial side LLIDs for the one or more CNUs having accessed the OCU comprises: allocating, by the OCU, the one or more coaxial side LLIDs for the one or more CNUs registered on the OCU, according to a Multi-Point Control Protocol, MPCP, discovery process executed by the CNUs; wherein the step of acquiring the one or more optical network side LLIDs allocated for the OCU by the OLT comprises: allocating, by the OLT, the one or more optical network side LLIDs for the OCU according to the one or more coaxial side LLIDs allocated for the one or more CNUs by the OCU, and transmitting the allocated one or more optical network side LLIDs to the OCU; wherein the step of allocating, by the OLT, the one or more optical network side LLIDs for the OCU according to the one or more coaxial side LLIDs allocated for the one or more CNUs by the OCU comprises: acquiring, by the OLT, the number of the coaxial side LLIDs allocated for the one or more CNUs by the OCU, according to an MPCP discovery process executed by the OCU, and allocating, for the OCU, optical network side LLIDs of which the number is not less than that of the coaxial side LLIDs. allocating, by an Optical Coax Unit, OCU, one or more coaxial side Logical Link Identifiers, LLIDs, for one or more Coaxial Network Units, CNUs, having accessed the OCU, and acquiring one or more optical network side LLIDs allocated for the OCU by an Optical Line Terminal, OLT; and establishing a mapping relationship between the coaxial side LLIDs and the optical network side LLIDs, and scheduling a data message of one of the CNUs according to the mapping relationship; wherein the step of allocating, by the OCU, the one or more coaxial side LLIDs for the one or more CNUs having accessed the OCU comprises: allocating, by the OCU, the one or more coaxial side LLIDs for the one or more CNUs registered on the OCU, according to a Multi-Point Control Protocol, MPCP, discovery process executed by the CNUs; wherein the step of acquiring the one or more optical network side LLIDs allocated for the OCU by the OLT comprises: allocating, by the OLT, the one or more optical network side LLIDs for the OCU according to the one or more coaxial side LLIDs allocated for the one or more CNUs by the OCU, and transmitting the allocated one or more optical network side LLIDs to the OCU; wherein the step of allocating, by the OLT, the one or more optical network side LLIDs for the OCU according to the one or more coaxial side LLIDs allocated for the one or more CNUs by the OCU comprises: acquiring, by the OLT, the number of the coaxial side LLIDs allocated for the one or more CNUs by the OCU, according to an MPCP discovery process executed by the OCU, and allocating, for the OCU, optical network side LLIDs of which the number is not less than that of the coaxial side LLIDs.