FTTB, when referred to as “Fiber-to-the-Basement,” specifically denotes a broadband network architecture where the optical fiber terminates in the basement of a multi-unit building, such as an apartment complex or office building. From the basement, other distribution methods (like Ethernet, coaxial cable, or even Digital Subscriber Line technologies) are utilized to connect individual units or offices in the building.

Key Aspects of FTTB (Fiber-to-the-Basement):


  • Optical Line Terminal (OLT): Located at the ISP’s central office, this device connects the FTTB service to the broader internet.
  • Basement Termination Point: The location in the building’s basement where the optical fiber ends. Here, it connects to a distribution hub, switch, or DSLAM, depending on the internal distribution technology used.
  • End-User Connection: Inside each unit or office, a modem, router, or Optical Network Unit (ONU) is used to connect devices to the network.


  • The speed and performance for end-users can vary based on the internal distribution method used. While fiber offers high speeds, the final speed at each apartment or office depends on the quality and type of the internal distribution network.


  • Infrastructure Cost Savings: By terminating the fiber in the basement and using existing in-building wiring, the deployment can be more cost-effective than running fiber to every individual unit.
  • Reliability: Fiber provides a stable and high-speed backbone up to the basement.


  • Internal Wiring Quality: The existing in-building wiring might degrade the quality of the connection, especially if it’s old or not well-maintained.
  • Speed Limitations: While the backbone is high-speed fiber, the distribution inside the building can limit the speed if not modernized.

Use Cases:

  • Older Buildings: In some older structures, it might be challenging to run new wiring to every unit. In such cases, FTTB can leverage existing infrastructure while still providing improved speeds.

Comparison to Other Fiber Solutions:

  • FTTH (Fiber-to-the-Home): Fiber runs directly to individual homes, offering the highest speeds.
  • FTTB (Fiber-to-the-Building, broader definition): Fiber runs to the building with various distribution methods used internally, not strictly to the basement.
  • FTTN (Fiber-to-the-Node): Fiber reaches a neighborhood node, and existing copper lines provide the final connection.

In summary, Fiber-to-the-Basement is a specific type of FTTB deployment that focuses on delivering fiber to the basement of a building and using other means for internal distribution. This approach can be efficient and cost-effective, especially in buildings where running new internal cabling to each unit is challenging or cost-prohibitive.