History and Standards

Standards for passive optical networks (PONs) have been developed by the International Telecommunication Union (ITU) and the IEEE.

ITU PON Standards

APON - The first PON solution developed in the 1990s according to the International Telecommunications Union (ITU) standard for PON networks was Asynchronous Transfer Mode PON (ATM-PON), also known as APON, with a speed of 622 Mbps. This is currently a high-speed network. APON allowed ISPs to serve multiple customers from a single router and use unpowered hubs to send data to end users.

BPON - The ITU APON standard was enhanced and evolved into Broadband PON (BPON) in 2007. BPON has upstream transmission rates of up to 622 Mbps and upstream rates of 155 Mbps to 622 Mbps.

GPON - In the early 2000s, another ITU G.984 standard, Gigabit-capable PON (GPON), emerged, which uses asynchronous transfer mode (ATM) and allows the speed of data communication to be adjusted for each user. GPON increased the downstream data rate to 2.5 Gb/s and the upstream data rate to 1.25 Gb/s. The GPON standard also specifies protocols for error correction, encryption (AES), link control (OMCI), and password or serial number authentication. In 2014, the standard was expanded to include wavelength-division multiplexing (WDM), which allowed multiple services (video, data, and voice) to be transmitted over the same fiber.

XG-PON / 10G PON - 10G-PON (also known as XG-PON) is the next-generation G.987 standard developed by the ITU in 2010. Asymmetric 10G-PON (XG-PON1) allows for downstream speeds of 10 Gbps and upstream speeds of 2.5 Gbps.

NG-PON2/TWDM-PON - The NG-PON2 standard developed by the ITU in 2015 provides an architecture that uses wavelength division multiplexing (TWDM) with 4 or more wavelengths per fiber, each of which can provide a symmetrical transmission rate of 2.5 Gbps or 10 Gbps.

XGS-PON - Introduced in 2016, the XGS-PON standard now provides synchronous transmission speeds of up to 10 Gb/s downstream and upstream. XGS-PON is not, as one might think, an evolution of XG-PON, but is an evolution of the NG-PON2 standard. XGS-PON uses different wavelengths for transmission than the original GPON standard, allowing simultaneous transmission of GPON, XGS-PON and NG-PON2.

The ITU continues to develop higher speed passive optical networking standards, including 25G-PON and 50G PON standards.

IEEE PON standards

EPON - In 2004, the IEEE published an alternative standard to the ITU standard called EPON, which based communications on the bidirectional Ethernet protocol. Ethernet Passive Optical Network (EPON) uses packets for synchronous communication (instead of ATM - Asynchronous Transfer Mode used in GPON) and provides bandwidth up to 1 Gbps.

GEPON - was another standard issued by the IEEE that enabled 10 Gb/s speeds.

10G-EPON - ratified by the IEEE in 2009. The 10G-EPON standard provides either symmetrical transmission at 10 Gb/s downstream and upstream, or asymmetrical transmission at 10 Gb/s downstream and 1 Gb/s upstream.