In the project of the Optical Fiber Access Network, the end-user has two nouns, ONU and ONT. However, many people are not quite sure what the two words mean.
The optical fiber is connected to the ONU through the passive optical network equipment (ODN). After the branch is connected to the ONU, the ONU acts as an optical port. The user port is used as the Ethernet port to directly access the Internet.
First, we should know these nouns:
FTTH: fiber to the home,
FTTO: fiber to the office,
FTTB: fiber to the building,
OLT: Optical line terminal,
ODN: Optical wiring network,
ONU: Optical network unit,
ONT: Optical network terminal.
In the different environment, the comparison of ONT and ONU is different.
In the FTTH, ONU refers to an optical network device connected to the branch fiber of the ODN. ONT refers to the optical network device connected to the end user (that is, our home).
When the carrier fiber enters the home, there will be a fiber-optic modem. We usually say that the optical cat is connected to the branch fiber of the ODN and also connected to the end user. It can be called ONU or ONT.
So, at this time, ONU=ONT.
In the FTTB, this ONU box is placed at the entrance of our house, like the style of the main meter in each corridor.
At this time, the small device connected to the ODN fiber can not be in the end user’s home. We can’t just equate the ONT with the ONU.
FTTB’s ONU box, a fiber comes in, and branches out a number of network cables. The MDU Multiple Dwelling Unit multi-user unit in the FTTB is one of the ONUs. MDU can lead to multiple network cables.
To describe simply:
FTTB “fiber to the building”, the 16-port ONU is placed in the unit box in the corridor, there are 16 ONTs in the ONU, and each ONT output is a network cable (electric signal), which reaches each user terminal through the network cable in the corridor.
FTTH “Fiber to the Home”, the 1 to 16 splitter is placed in the cell box in the corridor, and then through the fiber optic cable in the corridor to each user, each user is connected to an ONT. It is equivalent to dismantling the ONU, so that the terminal device is infinitely close to the user.
The ONT can be understood as an ONU with only one port.