In STAT (Port Status) mode on a Cisco switch, what do the different port LED colors indicate?
Off = no link, green = link up, blinking green = activity, amber = blocked by STP (Spanning Tree Protocol).
| LED State | STAT Mode Meaning |
|---|---|
| Off | No link or port is shutdown |
| Solid Green | Link is up |
| Blinking Green | Port is actively sending/receiving data |
| Amber | Port is blocked by STP (preventing a loop) |
| Blinking Amber | Port is blocked by STP (preventing a loop) |
| Alternating Green/Amber | Link fault detected |
This is the default mode — STAT is selected when the STAT LED is green — so it is what you see on a switch nobody has touched.
Read amber carefully: it is a healthy state, not a fault. Spanning Tree Protocol deliberately blocks one port of every redundant loop so frames cannot circle forever, and that blocked port sits amber while the rest forward. An amber port on a network with redundant links is STP doing its job; what should worry you is alternating green/amber, which reports an actual link fault.
Tip: Green = good, Amber = blocked/problem. If you see amber on a port, think Spanning Tree Protocol.