Understanding FTTx: Difference between ONU and ONT
Understanding FTTx: Difference between ONU and ONT
The EPON OLT is a device serving as the endpoint for the service provider in a passive optical network. In other words, the Optical Line Terminal (OLT) manages the Ethernet Passive Optical Network (EPON). This technology offers multiple services thanks to its point-to-multipoint passive optical transmission.
1. Definition
ONU refers to optical network unit. It comes from the IEEE standard.
ONT designates an optical network terminal. It comes from the ITU-T standard.
2. Implementation
In a passive optical network (PON), there is a passive optical splitter between the OLT and the ONU/ONT. The ONU/ONT collects and caches the Ethernet data that users need. Then it sends the data to the OLT based on the assigned transmission window. It can also receive data from the OLT. The UN/ONT will respond to the OLT if it needs to receive data.
However, there may be other networks like Ethernet between the ONU and the users. The UN is still located outside. It can be placed in corridors and certain public areas.
The ONT is deployed directly on the user side. You can think of the ONT as part of the ONU.
3. Types of ONU/ONT
Due to different functions, occasions and standards, there are different ONU/ONT such as xPON/EPON/GPON ONU, POE ONU and CATV ONU. Furthermore, depending on deployment occasions, ONUs can be classified into SFU, HGU, SBU, MDU, MTU, etc.
Here we will mainly introduce ONU HGU, which is mostly applied in FTTH. For example, the ELFAM 4GE+1POTS+ac WiFi+USB HGU ONU is designed to meet the demand for FTTH and triple-play services.
The HGU ONU deployment strategy is similar to that of SFU terminals, except that the ONU and RG functions are integrated into the hardware. Compared to SFU, it can perform more complex control and management functions.
You can learn more about ONU/ONT routers on the ELFCAM product page. Comment below to let us know if you have any questions!
