OLT Physical Composition

- Sep 26, 2019-

OLT usually consists of the following parts:


1) Control boards (also known as master boards or super control units) usually have two boards in one OLT.

2) DC power supply board (power supply from switching power supply to minus 48 volts) is also the main and spare two boards.

3) Fan Unit (Heat Dissipation of Main Equipment and Environmental Monitoring, etc.)

4) Frame (or Business Frame)

5) Uplink board: GE optical interface board (including button board), optical transceiver integrated module, a general board is two GE ports (currently 10GE has been commercially used), upstream board is connected to BRAS (broadband remote access server) convergence switch or direct BRAS equipment and SR equipment through transmission (OTN transmission), if there is IPTV industry. The service also needs to be connected to the corresponding BNG equipment. The upstream board can reach 10-40KM according to the different transmission distance of the optical module (no transmission in the middle).


6) Downlink board (also known as business version or PON board), OLT devices generally have multi-port PON board (such as a board with eight PON ports), each port down through the splitter (no more than 1:64) to connect the ONT terminal.

The transmission distance and attenuation of downlink panel are limited because of the distance measurement between ONT and OLT. For example, 8-port GPON OLT interface board (including pluggable ClassB + optical module) requires ODN to be within - 28 db, 8-port GPON OLT interface board (including pluggable ClassC + optical module) requires ODN transmission to be within - 32 db; however, considering later maintenance factors and other comprehensive reasons, it requires that the board of ClassB + optical module be controlled within - 25 dB in the initial project. Within this range, the board of ClassC + optical module is controlled within - 29db.

7) According to business needs, OLT can also insert (can be mixed) TDM service version, Ethernet service version, 16-way E1 service version and other boards.

8) The new OLT equipment must consider the full configuration power consumption (about 1400W) to calculate the size of the power line, the size of the empty occupancy (occupying two groups, one main equipment). According to previous experience, 63A is generally used for open, 16mm 2 for diameter, 16mm 2 for multi-strand copper core (flame retardant), 16mm 2 for ground wire and yellow-green copper core wire.

9) Note that OLT upstream terminal occupancy is easy to open without problems, downstream terminal occupancy should be considered clearly. The length of tail fibers should be measured well (optical jumping fibers are provided by manufacturers and power line manufacturers, but the length should be paid attention to). Optical jumping fiber (OLT side is SC head (down) and LC head up) flange type on ODF side.

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