Reference Guide

Stacking | 933
Locating an S4820T within a Stack
The S4820T has an LED which is used for the purpose of identifying a particular unit within a stack. This
LED is located on the PSU side of the S4820T, and is called the “Location” LED. Use the
stack-unit
location-led
command to control this LED:
FTOS#stack-unit 0 location-led ?
off Stack unit location LED off
on Stack unit location LED on
Influence Management Unit Selection on an S-Series Stack
Stack Priority is the system variable that FTOS uses to determine which units in the stack will be the
master and standby management units. If multiple units tie for highest priority, the unit with the highest
MAC address prevails.
If management was determined by priority only, a change in management occurs when:
• the management unit is powered down or a failover occurs
• you disconnect the management unit from the stack
When the management unit fails, the unit disappears from the stack topology. At that time, the standby unit
detects the communication loss and switches from the standby unit role to the management unit role in the
stack. From the remaining units in the stack, the system selects a new standby unit based on the unit
priority using the same algorithm used when the stack was initially created. When the failed unit recovers,
it takes the next available role, usually that of a stack member.
Task Command Syntax Command Mode
Influence the selection of the stack management units. The unit with the
numerically highest priority is elected the master management unit, and
the unit with the second highest priority is the standby unit.
Default: 0
Range: 1-14
stack-unit priority
CONFIGURATION