POL (Passive Optical LAN) uses optical fiber and passive optical splitting to replace the cascade of floor switches, and a thin fiber is pulled from the computer room to the room. It has only three layers: OLT, optical splitting network, and ONU. If you understand the responsibilities of each layer, it is not difficult to build a campus network.

Computer room OLT: Put aggregation into the computer room

The OLT is placed in the core computer room and does the original work of aggregation and access switches. A PON port usually provides 2.5G or 10G downlink bandwidth, which is time-shared to the rooms below; it is commonly used in computer room uplinks.SFP 2.5G single mode dual fiber 20KM optical moduleTo connect to core switching, the distance between buildings is sufficient. The equipment is small but concentrated, and the UPS can protect the computer room, and the lifeblood of the entire network is stable.

Optical splitting network: a passive segment that changes from one fiber to multiple fibers

There is a passive optical splitting network between the OLT and the room: a PLC optical splitter splits one fiber into 8, 16 or 32 lines and is installed in the corridor box or weak current well. It does not require power supply and is almost maintenance-free. The trade-off is fixed insertion loss, which typically works out to about 17dB for a 1:32 split, so usually leave a 3dB margin in the link budget and clean each connector in place.

Room ONU: change the light back to the network port

An ONU is placed in each dormitory and each classroom to restore the optical signal to a Gigabit network port or Wi-Fi. Computers and APs are directly connected with jumpers, and there are no access switches on the floor. For office building scenes, please refer toIntegrated wiring and all-optical network FTTH project for high-tech park office buildings, the same applies to dormitories and wards.

After looking at the three layers, we can find that POL equipment is concentrated on jumpers, pigtails and modules; EB-LINK'sCampus network and FTTH integrated cabling solutionThere is an itemized list on the page, and the reporting point can help check light splitting and loss.