Optical Line Terminal (OLT)
An optical line terminal is the active equipment at the provider's end of a passive optical network that sends traffic to, and collects traffic from, all the customer terminals on that network.
What is Optical Line Terminal (OLT)?
The OLT is the starting point of a PON. It is usually installed in the central office or exchange, and links the passive fibre network to the provider's core network, typically through Ethernet uplinks to a switch or router. It converts traffic between the electrical form used in the core and the optical signals sent over the fibre. It also controls access to the shared fibre: it decides when each ONT may transmit upstream, measures the distance to each one ("ranging") and enforces security and authentication.
How it works
An OLT chassis usually contains PON line cards (each with several PON ports), switching and control modules, uplink ports and redundant power supplies, often 48 V DC. Downstream, it broadcasts data to every ONT on a port, encrypted so that each ONT reads only its own traffic. Upstream, ONTs take turns in time slots the OLT allocates. Typical reach across the ODN is up to about 20 km.