Filter
Top Products
5-10
Catalyst 3750 Switch Software Configuration Guide
OL-8550-09
Chapter 5 Managing Switch Stacks
Understanding Stacks
All stack members use the SDM template configured on the stack master. If the stack master is using an
aggregator template, only Catalyst 3750-12S switches can be stack members. All other switches
attempting to join this switch stack enter SDM-mismatch mode. These switches can join the stack only
when the stack master is running a desktop SDM template.
We recommend that your stack master use an aggregator template only if you plan to create a switch
stack of Catalyst 3750-12S switches. If you plan to have a switch stack with different Catalyst 3750
switch models, configure the stack master to use one of the desktop templates.
Note Version-mismatch (VM) mode has priority over SDM-mismatch mode. If a VM-mode condition and an
SDM-mismatch mode exist, the switch stack attempts to resolve the VM-mode condition first.
You can use the show switch privileged EXEC command to see if any stack members are in
SDM-mismatch mode.
For more information about SDM templates and SDM-mismatch mode, see Chapter 8, “Configuring
SDM Templates.”
Stack Software Compatibility Recommendations
All stack members must run the same Cisco IOS software version to ensure compatibility in the stack
protocol version among the members.
Stack Protocol Version Compatibility
The stack protocol version has a major version number and a minor version number (for example 1.4,
where 1 is the major version number and 4 is the minor version number).
Switches with the same Cisco IOS software version have the same stack protocol version. All features
function properly across the stack. These switches with the same software version as the master
immediately join the stack.
If an incompatibility exists, a system message describes the cause of the incompatibility on the specific
stack members. The master sends the message to all members.
For more information, see the “Major Version Number Incompatibility Among Switches” procedure on
page 5-10 and the “Minor Version Number Incompatibility Among Switches” procedure on page 5-10.
Major Version Number Incompatibility Among Switches
Switches with different Cisco IOS software versions likely have different stack protocol versions.
Switches with different major version numbers are incompatible and cannot exist in the same stack.
Minor Version Number Incompatibility Among Switches
Switches with the same major version number but with a different minor version number as the master
are considered partially compatible. When connected to a stack, a partially compatible switch enters
version-mismatch mode and cannot join the stack as a fully functioning member. The software detects