What are the different types of PON (Passive Optical Networks) and what are they used for?
What are the different types of PON (Passive Optical Networks) and what are they used for?
The EPON OLT is a device serving as the endpoint for the service provider in a passive optical network. In other words, the Optical Line Terminal (OLT) manages the Ethernet Passive Optical Network (EPON). This technology offers multiple services thanks to its point-to-multipoint passive optical transmission.
1. APON (ATM Passive Optical Networks)
This was the very first of the PON standards and was based on ATM (Asynchronous Transfer Mode). ATM is a switching technique used by telecommunications networks that uses asynchronous time multiplexing to encode data into small, fixed-size cells. This technique is different from Ethernet or the Internet, which use variable packet sizes for data or frames.
It was used for commercial applications.
2. BPON (Broadband PON)
BPON is a standard based on APON. It adds support for WDM (wavelength division multiplexing), dynamic and higher upstream bandwidth allocation, and survivability. It also created a standard management interface, called OMCI, between the OLT and the ONU/ONT, thus allowing the creation of mixed networks.
BPON is typically offered at 622 Mbps downstream and 155 Mbps upstream. However, its ATM structure and bandwidth limitations do not make it ideal for video, leading to its development being halted. Instead, BPON networks will be converted to EPON or GPON over time.
3. EPON (Ethernet PON)
EPON is a competing business to GPON, which uses Ethernet packets instead of ATM cells.
Ethernet PON employs a unique Layer 2 network that uses Internet Protocol (IP) to transport data, voice and video. It typically provides symmetrical bandwidth of 1 Gbps, making it very popular in modern networks.
4. GE-PON (for Gigabit Ethernet PON)
GEPON is still evolving, but it requires multiple protocols through translation to support the native Generic Encapsulation Method (GEM) transport layer. This emulation supports ATM, Ethernet and WDM protocols. It is widely deployed in Asia and uses Ethernet as its native protocol. It simplifies synchronization and reduces costs by using 2,5 Gbps symmetric data streams. The complexity is less and the cost is lower than GPON.
5. GPON (Gigabit Ethernet PON)
GPON provides three Layer 2 networks: ATM for voice, Ethernet for data and proprietary encapsulation for voice. It offers 1.25 Gbit/s or 2.5 Gbit/s downstream and upstream bandwidths scalable from 155 Mbit/s to 2.5 Gbit/s.
An example of a GPON product is the VSOL GPON ONU&OLT. You can read more about GPON here.
