A method and apparatus for communicating streaming data, such as audio and video streams, isochronously over a network. The invention may be utilized with power-line communication (50) networks or other IP-based networks. Hardware (82) is configured for packetizing the streaming data, such as MPEG streaming data, which is communicated at the IP physical layer within a contention-free period within each communication cycle (32a and 32b). A reservation mechanism utilizes back-offs to allow a single transmitter to reserve a slot for isochronous communication of a given stream of data. A processing element handles packetizing only for asynchronous communication of data within the remaining portion of each communication cycle which is referred to as a contention period (34), as a number of transmitters may vie for communication during that interval. Addressing for the isochronous communication is performed with MAC addressing instead of IP addressing. Existing IP stack and protocols can be reused for upper layer control mechanisms.