Cisco device LEDs: system and port lights, green vs amber, solid vs blinking, and what they tell an engineer on the phone

Cisco switches and routers have LEDs on the front panel that give a quick health report without logging in. As an entry-level technician, you may be the person standing in the wiring closet while a senior engineer on the phone asks what the lights are doing. Describing them accurately, including color and whether each is solid, blinking or off, can save a lot of time.