ONUs, or Optical Network Units, are powered through a technology known as Power over Ethernet (PoE) or with the use of external power supplies. PoE simplifies the process by transmitting both electrical power and data over the same Ethernet cable. In this setup, the network switch or PoE injector, acting as the Power Sourcing Equipment (PSE), injects power into the Ethernet cable. The ONU, functioning as the Powered Device (PD), receives both power and data through the Ethernet cable. This approach eliminates the need for a separate power source for each ONU, making installations more straightforward and cost-effective.