OLT is an optical line terminal, ONU is an optical network unit (ONU), they are all optical transmission network connection equipment. It is two necessary modules in PON: PON (Passive Optical Network: passive optical network). PON (passive optical network) refers to (optical distribution network) does not contain any electronic devices and electronic power supply, ODN is composed of passive devices such as optical splitter (Splitter), does not require expensive active electronic equipment. A passive optical network includes an optical line terminal (OLT) installed at the central control station, and a batch of supporting optical network units (ONUs) installed at the user site. The optical distribution network (ODN) between the OLT and ONU contains optical fibers and passive splitters or couplers.
Routers and switches are data exchange equipment.
ODN (Optical Distribution Network) is an FTTH optical cable network based on PON equipment. Its role is to provide an optical transmission channel between the OLT and the ONU. From the functional point of view, ODN can be divided into four parts: the feeder optical cable subsystem, the distribution optical cable subsystem, the indoor cable optical cable subsystem and the optical fiber terminal subsystem from the office end to the user end.
ONT is an integral part of ONU.
FTTB “optical fiber to the building”, 16 ONUs are placed in the unit box in the corridor. There are 16 ONTs in the ONU. Each ONT outputs a network cable (electrical signal) and reaches each user end through the network cable in the corridor.
FTTH “fiber-to-the-home”, put a 1 to 16 splitter in the unit box in the corridor, and then reach each user through the covered fiber in the corridor, and each user terminates an ONT. It is equivalent to dismantling the ONU, so that the terminal equipment is infinitely close to the user.
ONT can be understood as an ONU with only one port.