the normal operation of protocols, such as Spanning
Tree, LACP, or GVRP features.
A redundant power supply has experienced a fault.
The switch has overheated.
The port may have an internal hardware failure. The
port may be denied PoE power. The port may be
detecting an external PD fault.
A redundant power supply is not connected to an
active AC power source.
Table 27 Stacked Switch and Stacking Module LED Error Indicators
If it does not, the problem may be with the cabling
between the devices, the connectors on the cable,
or the configuration of the device on the remote end
of the cable.
Use the switch console to check the port's
configuration to confirm whether the port is
administratively disabled or placed in a "blocking"
state by the normal operation of one or more
Check the Port Status using the show interfaces
command to confirm whether the port is
configured as "disabled".
Review the switch configuration to confirm which
protocols are operating on the port. Use the
appropriate feature show commands to confirm
whether the port is put into a "blocking" state.
For software troubleshooting tips, see the chapter
"Troubleshooting" in the Management and
Configuration Guide for your switch at
At least one power supply must be operating properly.
Check the power supply to make sure it is plugged in
to an active power source. If this is ok but the LEDs are
still blinking, the power supply may have failed. Unplug
the power supply, wait for 5 seconds for residual charge
to dissipate, and then plug the power supply. If the fault
light is still blinking, replace the power supply.
Check to ensure the fans are functioning correctly. See
for more information.
Check the port for a hardware failure, this may require
a reboot of the switch. Check the port for correct PoE
configuration and allocation. Also check the external
PD for a fault.
(At least one power supply must be operating properly.)
Connect the unplugged power supply to an AC power
source, using a supported power cord for your
Back side of chassis
Diagnosing with the LEDs