Ports 49~ 50 Mini-Gbic Status Leds - D-Link DES-1250G Manual

On When the Amber light is on, the respective port is connected to a
(Amber) 100Mbps Fast Ethernet network.
Off : When the respective port is connected to a 10Mbps Ethernet or No link.

Ports 49~ 50 mini-GBIC Status LEDs

Link/ACT: Link/Activity
On : When the mini-GBIC transceiver is installed and connected to a
network, the Link/ACT LED lights on.
Blinking : When the LED is blinking, the mini-GBIC module is receiving data on a
network.
Off : No link.