Dell PowerVault 51F (8P Fibre Channel Switch) - Manual (Page 148)

A-10 Installation and Troubleshooting Guide
Diag_Flt: the port failed diagnostics (defective G_Port
card or motherboard)
Port is OK (Solid Green LED):
The port is online and connected to a device over the cable.
Port is segmented (Slow Flashing Green LED):
Port is online but segmented.
Please check for loopback cable or incompatible switch.
Port has an internal loopback (Fast Flashing Green LED):
The port is configured as a loopback port by diagnostics to
verify the proper functioning of the internal Fibre Channel
port logic and paths between the interface and the central
memory. portEnable will put the port back online again.
Port is sending data (Flickering Green LED):
The port is online and transmitting/receiving frames.
Thermometer Error Message
Temperature out of range:
One or more temperature sensors have exceeded the minimum or
maximum allowed temperature reading (Minimum temperature is
zero degrees Centigrade, maximum is 75o degrees Centigrade).