EPON

EPON, or Ethernet Passive Optical Network, is a family of standardized access networks that deliver Ethernet services over a passive optical network. In an EPON architecture, an Optical Line Terminal (OLT) at the service provider’s facility communicates with multiple Optical Network Units (ONUs) at subscriber sites through optical fiber that is passively split by splitters. The portion of fiber from the OLT to the splitters is shared among users and does not require active electronics in the field.

Operation in EPON relies on a point-to-multipoint topology. Downstream traffic is broadcast from the OLT to all connected ONUs, while upstream traffic from ONUs is time-division multiplexed under control of a dynamic bandwidth allocator in the OLT to prevent collisions. This shared medium approach enables scalable, cost-effective delivery of services but requires careful bandwidth management and quality of service provisioning.

Standards and performance: The original 1 Gbit/s EPON is defined by IEEE 802.3ah-2004. 10G-EPON is defined by IEEE 802.3av-2009. Wavelengths commonly used are around 1310 nm for upstream and 1490 nm for downstream, with data rates typically at 1 Gbps for each direction, and higher rates for newer variants. EPON competes with GPON, which is ITU-T based and emphasizes different technical tradeoffs, equipment ecosystems, and deployment scenarios.

Deployment and use: EPON is widely used by telecommunications operators to provide fiber-based access to homes and businesses, offering advantages such as simple architecture and lower field maintenance due to passive optical components. Limitations include shared-medium contention and the need for effective dynamic bandwidth allocation, as well as competition from alternative PON technologies with different performance characteristics.