The main differences between EPON and GPON OLTs lie in the standards they comply with and the data processing methods they use. Which is better, EPON or GPON OLT?
EPON OLTs use the IEEE 802.3ah Ethernet standard. Like a typical LAN network, they transmit and receive data using simple Ethernet frames. This is the same language used by home computers and Wi-Fi routers. EPON OLTs essentially extend the familiar language of home networks to the home via fiber optic cable. This makes integration with existing IP-based systems extremely easy.
GPON OLTs, on the other hand, use the ITU-T G.984 standard. They use a special method called GEM (GPON Encapsulation Method) to transmit not only Internet data but also voice and video. This makes GPON OLTs suitable for multi-service networks requiring advanced traffic management.
2. Speed and Bandwidth Support
The OLT determines the amount of data that can be sent and received between users.
A typical EPON OLT port supports 1.25 Gbps in both the upstream and downstream directions. This is typically sufficient for basic internet usage such as browsing and streaming. Each home's devices are notified of when to send data (upstream) to the OLT, often with relatively simple scheduling.
GPON OLT ports offer 2.5 Gbps downstream and 1.25 Gbps upstream speeds, delivering superior performance for high-bandwidth services like HD video, cloud apps, and IP voice. This is due to the GPON OLT's built-in smarter, dynamic traffic control system known as DBA (Dynamic Bandwidth Allocation). The GPON OLT constantly checks the amount of data each home is actually attempting to transmit and then adjusts the "time slots" assigned to each home in real time with great precision. This often results in more efficient utilization of the entire fiber optic pipe.
3. Split Ratio and User Capacity
Both types can typically serve homes approximately 20 km (12 miles) away from the OLT. OLT ports are shared among multiple users using optical splitters. The number of users that can connect to a single OLT port is called the split ratio.
EPON OLTs typically support up to 64 users per port.
GPON OLTs support up to 128 users per port.
This means that GPON OLTs can handle more users per port, making them useful for large-scale Fiber to the Home (FTTH) deployments. However, if the network is not properly designed, performance may degrade as the number of users per port increases.
4. Network and Device Management:
EPON OLTs use standard Ethernet tools for connection health checks and basic management. While simple, it does not provide detailed control over all functions of the ONT, especially for complex services.
GPON OLTs use a powerful, dedicated management system called OMCI. OMCI is like a remote control system designed specifically for ONTs. The OLT can configure these devices in detail, troubleshoot problems remotely, and precisely configure various services (Internet, telephone, and TV). This is a significant advantage if your provider offers bundled services.
5. Device Compatibility
EPON OLTs only work with EPON ONUs, and GPON OLTs only with GPON ONUs. These devices cannot be mixed. Furthermore, if the OLT does not support the same standard as the ONUs, communication will not work properly.
When upgrading or expanding your network, make sure all devices are from the same system (EPON or GPON). Some OLTs support dual mode (XPON) and can recognize both EPON and GPON ONUs, providing greater flexibility.
6. Cost and Complexity
EPON OLTs are typically cheaper and easier to deploy and manage. Equipment costs are low and configuration is simple. This makes them ideal for small and medium-sized ISPs and enterprise networks.
GPON OLTs are more expensive. The increased complexity of GEM and OMCI can drive up costs, but they are widely used worldwide.