Reference Guide

• Inter-switch stacking link failure
• Switch insertion
• Switch removal
If the master switch goes off line, the standby replaces it as the new master and the switch with the next highest priority
or MAC address becomes standby.
Stack Master Election
The stack elects a master and standby unit at bootup time based on two criteria.
• Unit priority — User-configurable. The range is from 1 to 14. A higher value (14) means a higher priority. The
default is 1. By removing the stack-unit priority using the no stack-unit priority command, you can
set the priority back to the default value of zero. The unit with the highest priority is elected the master
management unit; the unit with the second highest priority is elected the standby unit.
• MAC address (in case of priority tie) — The unit with the higher MAC value becomes the master unit. The stack
takes the MAC address of the master unit and retains it unless it is reloaded.
To view which switch is the stack master, enter the show system command. The following example shows sample
output from an established stack.
A change in the stack master occurs when:
• You power down the stack master or bring the master switch offline.
• A failover of the master switch occurs.
• You disconnect the master switch from the stack.
When a stack reloads and all the units come up at the same time; for example, when all units boot up from flash, all units
participate in the election and the master and standby are chosen based on the priority or MAC address.
When the units do not boot up at the same time, such as when some units are powered down just after reloading and
powered up later to join the stack, they do not participate in the election process even though the units that boot up late
may have a higher priority configured. This happens because the master and standby have already been elected, hence
the unit that boots up late joins only as a member.
When an up and running standalone unit or stack is merged with another stack, based on election, the losing stack
reloads and the master unit of the winning stack becomes the master of the merged stack. For more details, see
sections Add Units to an Existing S-Series Stack and Remove Units or Front End Ports from a Stack. It is possible to reset
individual units to force them to give up the management role or reload the whole stack from the CLI to ensure a fully
synchronized bootup.
Example of Viewing Stack Members
FTOS#show system brief
Stack MAC : 00:01:e8:8c:53:32
Reload Type : normal-reload [Next boot : normal-reload]
-- Stack Info --
Unit UnitType Status ReqTyp CurTyp Version Ports
-----------------------------------------------------------------
0 Member not present
1 Management online S4810 S4810 4810-8-3-12-1447 64
2 Standby online S4810 S4810 4810-8-3-12-1447 64
3 Member online S4810 S4810 4810-8-3-12-1447 64
4 Member online S4810 S4810 4810-8-3-12-1447 64
5 Member not present
6 Member not present
7 Member not present
8 Member not present
9 Member not present
10 Member not present
764