The purpose of the
auto-upgrade feature is to allow a switch to be upgraded to a compatible
software image, so that the switch can join the switch stack.
When a new switch
attempts to join a switch stack, each stack member performs compatibility
checks with itself and the new switch. Each stack member sends the results of
the compatibility checks to the
active switch, which uses the results to determine
whether the switch can join the switch stack. If the software on the new switch
is incompatible with the switch stack, the new switch enters version-mismatch
If the auto-upgrade
feature is enabled on the new switch, the
active switch automatically upgrades the new
switch with the same software image running on a compatible stack member.
Auto-upgrade starts a few minutes after the mismatched software is detected
By default, auto-upgrade is enabled
auto-copy-sw global configuration command is enabled). You can
disable auto-upgrade by using the
auto-copy-sw global configuration command on the stack master.
You can check the status of auto-upgrade by using the
privileged EXEC command and by checking the
line in the display.
an auto-copy process and an auto-extract process.
automatically copies the software image running on any stack member to the new
switch to automatically upgrade it. Auto-copy occurs if auto-upgrade is
enabled, if there is enough flash memory in the new switch, and if the software
image running on the switch stack is suitable for the new switch.
A switch in
VM mode might not run all released software. For example, new switch hardware
is not recognized in earlier versions of software.
extraction (auto-extract) occurs when the auto-upgrade process cannot find the
appropriate software in the stack to copy to the new switch. In that case, the
auto-extract process searches all switches in the stack for the tar file needed
to upgrade the switch stack or the new switch. The tar file can be in any flash
file system in the switch stack or in the new switch. If a tar file suitable
for the new switch is found on a stack member, the process extracts the file
and automatically upgrades the new switch.
The auto-upgrade (auto-copy and
auto-extract) processes start a few minutes after the mismatched software is
When the auto-upgrade
process is complete, the new switch reloads and joins the stack as a fully
functioning member. If you have both stack cables connected during the reload,
network downtime does not occur because the switch stack operates on two rings.