Users Guide

Table Of Contents
Stacking 261
automatically routes around the failed unit. If the stack is not configured in a
ring topology, then the stack may split, and the isolated members will reboot
and re-elect a new management unit in the stack. No changes or
configuration are applied to the other stack members; however, the dynamic
protocols will try to reconverge as the topology could change because of the
failed unit.
If you remove a unit and plan to renumber the stack, issue a no member
unit
command in Stack Configuration mode to delete the removed switch from
the configured stack member information.
How is the Firmware Updated on the Stack?
When adding a new switch to a stack, the Stack Firmware Synchronization
feature, if enabled, automatically synchronizes the firmware version with the
version running on the management unit in the stack per the configuration
on the primary switch. The synchronization operation may result in either
upgrade or downgrade of firmware on the mismatched stack member. Use the
boot auto-copy-sw command to enable stack firmware synchronization
(SFS).
Upgrading the firmware on a stack of switches is the same as upgrading the
firmware on a single switch. After downloading a new image by using the File
Download page or copy command, the downloaded image is distributed to all
the connected units of the stack. For more information about downloading
and installing images, see "Images and File Management" on page 551. When
copying firmware onto the switch in a stacked configuration, use the show sfs
and show version commands to check the status of stack firmware
synchronization prior to a reboot.
What is Stacking Standby?
The standby unit may be preconfigured or automatically selected. If the
current management unit in the stack fails, the standby unit becomes the
management unit in the stack. If no switch is preconfigured as the standby
unit, the software automatically selects a standby unit from among the
existing stack units.
When the failed primary resumes normal operation, it joins the stack as a
member (not as the primary) if the new management unit in the stack has
already been elected.