EPON protocol over coax (EPoC): overview and design issues from a MAC layer perspective?

We investigate the challenges in designing the network architecture for running EPON (Ethernet Passive Optical Network) Protocol over Coax, or EPoC in short. EPoC is the transparent extension of EPON over a cable operator's Hybrid Fiber-Coax (HFC) network, and uses a hybrid of optical and coaxial technologies to carry traffic to and from end-users and the Internet backbone. For managing and controlling such a hybrid network, a network operator will prefer to have a unified scheduling, management, and quality-of-service (QoS) environment that includes both the optical and coax portions of the network. This can be achieved by extending the EPON Medium Access Control (MAC) to run over the coax physical layer, to have a centralized end-to-end network control from the cable head-end to the end-users' premises. The use of the coax portion of the network is transparent to EPON protocol operation in the headend, as the same MAC runs over the entire network. In this article, we describe the architecture of EPoC, and outline how the EPON MAC Control, i.e., the EPON Multi-Point Control Protocol (MPCP) can be extended for designing an end-to-end Multi-Point MAC Control for EPoC. We explain the design of several MAC functions and their operation, including framing for coax, Ethernet frame fragmentation, generation of upstream and downstream Media Allocation Plans, and automatic discovery and registration of user equipment. With strong backing from both service operators and equipment vendors, EPoC is set to become a rapidly-evolving standard within the next few years, and the creation of the IEEE 802.3bn Task Force for EPoC is a major step in that direction.