Comprehensive Guide to ODN in PON Networks: Key Components & Future Trends
Updated at Nov 22nd 20241 min read
ODN of Passive Optical Network
An Optical Distribution Network (ODN) serves as the bridge in a Passive Optical Network (PON), transmitting optical signals from the Optical Line Terminal (OLT) to the Optical Network Unit or Terminal (ONU/ONT), thus linking a service provider's core network to end-users (residential or business).
Primary Functional Nodes in PON-ODN Systems
PON networks use a P2MP topology, forming an extensive optical distribution network. ODN connects multiple nodes, acting as the backbone for FTTx applications. For ease of understanding, ODN can be divided into three basic functional nodes:
Feeder Segment: Connects the central office to the fiber distribution point, providing long-distance coverage through backbone fiber cables.
Distribution Segment: Extends from the fiber distribution point to the user access point, allowing localized distribution of optical signals.
Drop Segment: Connects the user access point to end devices, completing the last segment of FTTH.
ODN Components for Fiber-to-the-Home
To achieve efficient signal transmission, ODN relies on three primary components: fiber optic cables, splitters, and optical connectors. These components play essential roles in transmission, distribution, and connection:
Fiber Optic Cables – Optical Signal Transmission
As the primary transmission medium, fiber optic cables carry signals from the OLT to ONU devices in homes or businesses, including HGU, ONT, and SFU. Common types include metro and drop cables, ensuring stable signal delivery over long distances.
Optical Splitters – Optical Signal Distribution
Optical splitters in PON networks are used to distribute optical signals from a single point to multiple endpoints. They are manufactured using PLC, FBT, or MEMS technology. PLC splitters, known for low insertion loss, wide bandwidth, and high reliability, have become the mainstream choice in modern optical networks. Splitters come in various packages—Bare Fiber, Mini Module, ABS Module, FHD, LGX, and 1U Rack—designed for different network scenarios. Learn more about PLC splitter: A Complete Guide to Selecting the Right FS PLC Splitter for Your Network
Optical Connectors – Connecting Fiber and Splitters
These connect fiber cables and splitters, ensuring continuity and stability in the optical path. Various types, including active connectors, mechanical splices, and field connectors, meet diverse deployment needs.
Additional Auxiliary Equipment – Network Connection and Management
ODN also incorporates devices such as Optical Distribution Frames (ODF), Fiber Distribution Terminals (FDT), Fiber Distribution Boxes (FDB), and Fiber Access Terminals (FAT) for organizing and managing fiber networks. Together, these components and equipment form an efficient ODN system, ensuring stable signal transmission to each end-user. This network structure enables homes and businesses to enjoy reliable fiber communication services.
ODN Network Architectures
In FTTH deployments, ODN architecture varies based on site complexity and user distribution, directly affecting investment costs. Based on splitter levels, location, and split ratio, common ODN network modes include:
Centralized Splitter Mode
This single-stage mode places splitters at large distribution nodes, such as community hubs or FDTs, suitable for serving over 144 users. FS high-density rack-mounted FHD/LGX 1×32 or 1×64 PLC splitters are designed for such applications, maximizing OLT port capacity while reducing infrastructure costs and simplifying maintenance.
Distributed Splitter Mode
Here, splitters are distributed in building telecom rooms or on walls, generally placing 1 to 4 splitters within large FATs or small FDTs, covering 36-144 users and suitable for medium-density user areas.
Two-stage Splitter Mode
This approach places secondary splitters at smaller distribution points, such as floor telecom rooms in high-rises or corridors in mid- to low-rise buildings. Usually, small FATs house 1 to 4 splitters per unit or floor, covering fewer than 36 users. This mode is ideal for low-density residential areas or industrial parks, with PLC splitters at ratios between 1:4 and 1:16.
Future Prospects of ODN
Future ODN development will focus on intelligence, multi-service support, high speed, eco-friendliness, and interoperability. Smart ODNs will offer self-monitoring and self-repair functions, increasing network efficiency, while higher-speed and larger-capacity designs will accommodate diverse services like video and voice. With the growing adoption of PON, interoperability and standardization will ensure compatibility across devices. As a global solutions provider, FS actively explores these advancements, offering enhanced high-speed passive optical network solutions. To learn more about optimizing network efficiency, contact FS.com.