- The top half of the number blinks if the switch is the master
- Bottom half blinks if it is the backup.
- If the LED is steadily lit, the switch is neither master nor backup.
- If the LED is off the switch is not configured as a member of a stack.
In addition to the Stack Number Indicator, each stacking port has an LED. The LED is steady green if the link is OK, blinking green if traffic is present, and off if no signal is present.