GPON
GPON stands
for Gigabit Passive Optical Network. It is a type of high-speed network
standard for Internet access, mainly used for broadband services over optical
fiber. Here are the details of GPON and its main features:
1. Network Structure: GPON is based on
point-to-multipoint architecture, which means that a single fiber optic cable
can serve multiple locations using passive optical splitters. This is in
contrast to the point-to-point model, where each location requires its own
fiber optic cable.
2. OLT and ONT/ONU: OLT (Optical Line
Terminal): This is a device located at the service provider's headquarters. It
transmits data to multiple users and also collects data from users. ONT
(Optical Network Terminal) or ONU (Optical Network Unit): This is a device
located at the customer's premises. It receives data sent from the OLT. The
terms ONT and ONU are sometimes used interchangeably, but ONT is usually
customer facing and ONU can refer to a larger device that serves multiple customers
in some situations.
3. Speed and Efficiency: GPON offers
asymmetric bandwidth with downstream rates of up to 2.5 Gbit/s and upstream
rates of up to 1.25 Gbit/s. However, there are advancements and new standards
that can provide even higher rates. The use of passive splitters in the network
eliminates the need for power in the distribution network, reducing maintenance
costs and improving reliability.
4. Wavelengths: GPON uses wavelength
division multiplexing (WDM), which allows multiple signals with different
wavelengths (colors) of light to be transmitted over a single optical fiber.
Typically, two wavelengths are used, one for downstream data and one for
upstream data.
5. Layer 2 Protocols: GPON uses Ethernet
and TDM (Time Division Multiplexing) for data and voice services respectively.
This makes it extremely versatile and allows a variety of services to be
offered over a single infrastructure.
6. Distance
and coverage: The GPON standard allows for coverage of up to 20 kilometers
(about 12.4 miles) between the central office and the end user, making it
suitable for both densely populated urban areas and large rural areas.
