Systems and methods are provided for transparently transmitting multiple constant bitrate (CBR) data streams over a packet network with reduced delay. Example embodiments provide packetizers and depacketizers for multiplexing and demultiplexing multiple common public radio interface (CPRI) data streams for transport between remote units and baseband units over packet networks. The systems and methods disclosed herein use time-division-multiplexing to map multiple CBR clients directly into a packet such that each CBR client can be recovered at the destination with its original clock and with information that allows its residence time in the packet domain to be calculated. The systems and methods disclosed herein allow packet based networks, such as the existing Packet Transport Network (PTN), to be used for C-RAN fronthaul applications with strict end-to-end delay requirements.