Fiber Optic Networking - What is FTTP, FTTH, FTTB, and FTTD?
By Colin Yao
FTTP stands for Fiber To The Premises which is one type of fiber optic communication
delivery in which a optical fiber connection is directly run to the customers' premises.
The P (premises) can be business, commercial, institutional and other applications where
fiber network connections are distributed to a campus, set of structures, or high density
building with a centrally located network operations center.
Some other FTTx such as FTTN (fiber to the node), FTTC (fiber to the curb) still depend
on copper wires for "last mile" (final connection) to the customers' premises which
contrasts with FTTP. FTTP can be further categorized into FTTH (fiber to the home), FTTB
(fiber to the building), etc.
Network construction of FTTP
FTTP network can be divided into two major parts: optical portion and electrical portion.
1. Optical portion
Optical portion of the FTTP network is responsible for carrying optical signal to the
electrical portion (electrical portion is located in the customer's telecom room). Two
fiber configurations exist for the FTTP optical portion. These are direct fiber link and
shared fiber link.
Direct fiber link is the simplest form. One fiber is used for directly connecting the
central office to one customer. This type of connection provides the customer the biggest
bandwidth but is also the most expensive configuration. Shared fiber link means a single
fiber leaving the service providers central office is shared by many customers. Only at
the final moment, the fiber is split into many individual fiber to each customer.
There are two major competing technologies for the shared fiber link configuration:
active optical network (AON) and passive optical network (PON).
Active Optical Network (AON) is much more like traditional Ethernet computer networks.
It needs electrically powered equipment to buffer and distribute the signal such as
switches or routers. Each signal leaving the central office is routed only to the customer
intended by the router or switch. On the other hand, signals from the customers are
buffered by the router at the intersection avoiding colliding.
Passive Optical Network (PON) does not use any electrically powered equipment to buffer
and route the signals. Instead, the light signal from central office is divided and
distributed to all customers, even those who are not intended to. Once the light signal
arrives at the electrical portion, where it is converted to electrical signal by the
ONT(see below), the ONT decides whether to keep or discard the signal depending on its
intended destination.
2. Electrical portion
Electrical portion of the FTTP network receives optical signal and converts it to
traditional electrical signal which is then distributed to desktop computers via a LAN
copper wire network. This converting device is called an optical network termination(ONT).
The building's phone systems, LAN and cable TV system are then connected to the ONT.
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