Allied Telesis AT-S94 - Manual (Page 234)

Managing Stacking
Stacking Overview
Page 234
Exchanging Stacking Members
In normal operation of the stack, the running configuration file in the master is backed up to the secondary master
when the secondary master becomes part of the stack or when any stack configuration change is made. In the
event that the master goes down, the backup unit becomes the master with the stored configuration file. If this
event occurs and the original master recovers after a 10 minutes has elapsed, the secondary master will load its
running configuration file onto the original master, which will remain in a non-master status until the stack is
rebooted. This is also true if the orginal master switch is exchanged in the stack for a different switch having the
same stack ID # after the secondary master has assumed an active role for more than 10 minutes. Upon full stack
recovery, the original master will resume its master status with the original configuration.
Caution
If the master recovery takes less than ten minutes, the backup will reboot, relinquish master status and
accept the configuration from the new master. If the current configuration file was not previously loaded
onto the new switch before it is activated, then the current stack configuration will be lost.
Therefore, if a new switch is substituted for the original master switch, ATI recommends that you wait for
10 minutes or more after the backup has become the master before activating the new master switch. This
will insure that the integrity of the stack configuration will be maintained.
If a stack member with the same Unit ID replaces an existing Unit ID with the same Unit ID, the previous device
configuration is applied to the inserted stack member. If the new inserted device has either more ports or less
ports than the previous device, the relevant port configuration is applied to the new stack member.
The Secondary Master replaces the Stacking Master if the following events occur:
• The Stacking Master fails or is removed from the stack.
• Links from the Stacking Master to the stacking members fails.
• A soft switchover is performed via the web interface or the CLI.
Switching between the Stacking Master and the Secondary Master results in a limited service loss. Any dynamic
tables are relearned if a failure occurs. The Running Configuration file is synchronized between the Stacking
Master and the Secondary Master, and continues running on the Secondary Master.