4-4
Troubleshooting
Diagnosing with the LEDs
Diagnosing with the LEDs
Table 4-1 shows LED patterns on the switch that indicate problem conditions 
for general switch operation troubleshooting.
Table 4-2 shows LED patterns that indicate problem conditions for PoE 
troubleshooting.
LED patterns for General Switch Troubleshooting
1. Check in the table for the LED pattern you see on your switch.
2. Refer to the corresponding diagnostic tip on the next few pages.
Table 4-1. LED Error Indicators
LED Pattern Indicating Problems
Diagnostic 
Tips
Power Fault Test Fan Port Link LED
Off with 
power cord 
plugged in
111 1
➊
On Prolonged On Prolonged On
11
➋
On Flashing
2
Flashing
2
11
➌
On Flashing
2
Off Flashing
2
1
➍
On Flashing
2
Flashing
2
1
Flashing
2
➎
On Off Off
1
Off with cable 
connected
➏
On Off Off
1
On, but the port is not 
communicating
➐
1
This LED is not important for the diagnosis.
2
The flashing behavior is an on/off cycle once every 1.6 seconds, approximately.