OLT (Optical Line Terminal) this equipment integrates layer 3/layer 3 functionality into your PON solution. The function of an OLT is to control information across the fibre network, both upstream and downstream and distributes the fibre from the service provider, towards the subscriber and back again.   Optical Splitter-The function of the optical splitter is to split the wavelengths from one fibre core into several fibre strands. This happens on separate transceiving and receiving wavelengths coordinated by the SFP module.   SFP module – this device enables the laser from the OLT to be split into Rx and Tx wavelengths. 1490nm is reserved for downstream traffic whilst 1310nm is reserved for upstream.   ONU (Optical Network Unit) this unit is normally located at the end-users’ premises and is where the fibre light is converted into electrical signals to be distributed by Wi-Fi.