What is GPON?

Understand the GPON

Background Information
GPON is an alternative to Ethernet switching in campus networking. GPON replaces the traditional three-tier Ethernet design with a two-tier optic network which eliminates access and distribution Ethernet switches with passive optical devices. Cisco introduces GPON with the Catalyst GPON platform.

Terminology

• Gigabit-capable Passive Optical Network (GPON) - Standard for passive optical networks (PON) published by the ITU-T.

• Optical Distribution Network (ODN) - The physical fibre and optical devices that distribute signals to users in a telecommunications network. The ODN is composed of passive optical components (POS), such as optical fibers, and one or more passive optical splitters.

• Optical Network Termination (ONT) /Optical Network Units (ONU) - Connects end-user devices (desktop, phones, and so on) into the GPON network. Provides the optical to electrical signal conversion. ONTs also provide AES encryption via ONT key.

• Splitters - Used to aggregate or multiplex fiber optic signals to a single upstream fiber optical cable. Usually 1:32 ratio.

• Optical Line Terminal (OLT) - Device that aggregates all optical signals from ONTs into a single multiplexed beam of light which is then converted into an electrical signal, formatted to Ethernet packet type standards for Layer 2 or Layer 3 forwarding.

• Wavelength-Division Multiplexing (WDM) - Wavelength-division multiplexing (WDM) is a technology that multiplexes a number of optical carrier signals onto a single optical fiber that uses different wavelengths (that is, colors) of laser light.

• GEM GPON encapsulation method (GEM) -  A data frame transport scheme used in gigabit capable passive optical network (GPON) systems that is connection-oriented and that supports fragmentation of the user data frames into variable-sized transmission fragments

• Fiber to the X (FTTX) - FTTX is a generalization for several configurations of fiber deployment, arranged into two groups: FTTP/FTTH/FTTB (Fiber laid all the way to the premises/home/building) and FTTC/N (fiber laid to the cabinet/node, with copper wires to complete the connection).

• T-CONT/TCONT - Transmission Container

• OMCC - Optical Network Unit Management and Control Channel

• OMCI  - Optical Network Unit Management and Control Interface

• PCBd - Physical Control Block downstream

• TDM - Time Division Multiplexing

• TDMA - Time Division Multiple Access

Network Diagram