For DGS-1005A:
Power Indicator
This green indicator light is on when the Switch is receiving power; otherwise, it is off.
Link/Act/Speed
When connected to a 1000Mbps device, this LED indicator light is green when the port is connected to a device and will blink as data is transmitted or received.
When connected to a 10/100Mbps device, this LED indicator light is off when the port is connected to a device and will blink as data is transmitted or received.