How to distinguish optical access network OLT, ONU,
ODN, ONT?
The optical access network
is an access network that uses light as the transmission medium, instead of
copper wire, for access to every household. Optical access network generally
consists of three parts: OLT(optical
line terminal), ONU(optical network unit),
ODN(optical distribution network), among which OLT and ONU are the core
components of optical access network.
What is OLT?
The full name of OLT is
Optical Line Terminal. The OLT is an optical line terminal and a central office
equipment of telecommunications. It is used to connect optical fiber trunk
lines. It functions as a switch or router in a traditional communication
network. It is a device at the entrance and exit of the external network and
the internal network. Placed at the central office, the most important
executive functions are traffic scheduling, buffer control, and provision of
user-oriented passive optical network interfaces and bandwidth allocation. To
put it simply, it is to achieve two functions. For the upstream, it completes
the upstream access of the PON network; for the downstream, the acquired data
is sent and distributed to all ONU user terminal devices through the ODN
network.
What is ONU?
ONU is the Optical Network Unit. ONU has two
functions: to selectively receive the broadcast sent by OLT, and to receive the
OLT in response to the need to receive the data; Collect and cache the Ethernet
data that the user needs to send, and send the cached data to the OLT end
according to the assigned send window.
In FTTx network, different deployment ONU access
methods are also different, such as FTTC (Fiber To The Curb): ONU is placed in
the central computer room of the community; FTTB (Fiber To The Building): ONU
is placed in the junction box of the corridor; FTTH ( Fiber To The Home): ONU
is placed in home users.
What is ONT?
ONT is the Optical Network
Terminal, the most terminal unit of FTTH, commonly known as "optical
modem", similar to the xDSL electric modem. ONT is an optical network
terminal and is applied to end users, while ONU refers to an optical network
unit, and there may be other networks between it and the end user. ONT is an
integral part of ONU.
What is the
relationship between ONU and OLT?
OLT is the management side,
ONU is the terminal; ONU's business opening is all issued through OLT, and the
two are in a master-slave relationship. Multiple ONUs can be hung by the
splitter under an OLT.
What is ODN?
ODN is an Optical
Distribution Network, which is an optical transmission physical channel between
OLT and ONU. The main function is to complete the two-way transmission of
optical signals. It is usually composed of optical fiber cable, optical connector,
optical splitter and supporting equipment to install and connect these devices,
among which the most important component is the splitter.
