Optical Network Terminal

Optical network terminals

In fiber-to-the-premises systems, the signal is transmitted to the customer premises using optical fiber technologies. Unlike many conventional telephone technologies, this does not provide power for premises equipment, nor is it suitable for direct connection to customer equipment. An optical network terminal (ONT, an ITU-T term), also known as an optical network unit (ONU, an IEEE term), is used to terminate the optical fiber line, demultiplex the signal into its component parts (voice telephone, television, and Internet access), and provide power to customer telephones. If the device combines all these services into one it is known as an IAD. As the ONT must derive its power from the customer premises electrical supply, many ONTs have the option for a battery backup in order to maintain service in the event of a power outage or it will go in alarm mode if disconnected and customer may be notified of this. These terminals are used in both active optical networks and passive optical networks. Typically, an ONT connects via a fiber-optic cable to an OLT to complete a connection. An ONT can work in Single Family Unit/SFU mode (modem/bridge) or Home Gateway Unit/HGU mode (router). In passive optical networks, Management is provided by the OLT via OMCI, in case of a GPON connection, and OAM in case of a EPON connection. Authentication and encryption is done via LOID for EPON and PLOAM password, GPON serial number or others for GPON.