Reference Guide

698 | Stacking S-Series Switches
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Figure 39-1. S55 Stack Manager Redundancy
Management Unit Selection on S-Series Stacks
FTOS has a selection algorithm to decide which stack units will be the primary and secondary management
units. During the bootup of a single unit or the stack, FTOS compares the priority values of all of the units
in the stack and elects the unit with the numerically highest priority the primary, and the next highest
priority the secondary.
For example, if you add a powered standalone unit to a stack, either the standalone unit or the stack reloads
(excluding the new unit), depending on which has the higher priority, the new unit or the existing stack
manager. If the new unit has the higher priority, it becomes the new stack manager after the stack reloads.
All switches have a default priority of 1; if a priority tie occurs, the system with the highest MAC address
supersedes, as shown in Figure 39-2.
FTOS#show redundancy
--------- Stack-unit Status ---------
Mgmt ID: 1
Stack-unit ID: 0
Stack-unit Redundancy Role: Primary
Stack-unit State: Active
Stack-unit SW Version: SD8.3.5.1
Link to Peer: Up
--------- PEER Stack-unit Status --------------------
Stack-unit State: Standby
Peer stack-unit ID: 1
Stack-unit SW Version: SD8.3.5.1
--------- Stack-unit Redundancy Configuration --------------
Primary Stack-unit: mgmt-id 1
Auto Data Sync: Full
Failover Type: Hot Failover
Auto reboot Stack-unit: Disabled
Auto failover limit: 3 times in 60 minutes
--------- Stack-unit Failover Record ---------------------
Failover Count: 3
Last failover timestamp: Oct 30 2010 04:15:36
Last failover Reason: User request
Last failover type: Hot Failover
--------- Last Data Block Sync Record: ----------------------
Stack Unit Config: succeeded Oct 30 2010 04:16:13
Start-up Config: succeeded Oct 30 2010 04:16:13
Runtime Event Log: succeeded Oct 30 2010 04:16:13
Running Config: succeeded Oct 30 2010 04:16:13
ACL Mgr: succeeded Oct 30 2010 04:16:13
LACP: no block sync done
STP: no block sync done
SPAN: no block sync done
FTOS#