Quick Reference Guide

Stacking S-Series Switches | 87
Number Assignment on page 86). Use the show switch command (Figure 5-56 on page 88) to see the
status of the individual members in a stack.
It is possible to pre-configure the stack for new units. Use the
member command (see Stacking Commands
Overview on page 85) to accomplish this function. This will logically create the new unit and all the ports
connected to that unit. You can define the new unit in advance, and pre-configure the ports even though the
ports do not yet physically exist in the stack. If you do so, make sure you pre-assign the unit number to the
new unit so that it will get the proper configuration from the management unit when connected to the stack.
See the list of best practices (Best Practices on page 89). Pre-configured ports (not physically present)
display in the
show switch command report as “detached”.
Bear in mind that, if you connect a switch that already has a stack number that does not match the
pre-configuration you did (perhaps it was previously a member of another stack), the switch will be
assigned a default configuration by the management unit. If this occurs, use the
switch renumber
command to assign a stack number that matches the unit number you pre-configured for.
You can also use the the
switch renumber command if you want to remove a unit that is the current
backup to the management unit, and you want this new unit to assume the identity of that removed unit.
The management unit is in charge of the stack. If a new software image is loaded into the management
unit, the image will be automatically propagated to all units (in fact it is required that all units run the same
version of code). If configuration changes are made and saved, they will be saved to all switches, and
remembered by all switches, even if the switches are disconnected from the stack. The management IP
address is also included in that configuration information, so you could end up with duplicate addresses on
the network if you simply remove the stacking cables from units that are connected to the same network.
If the management unit were to be removed, or it became non-functional for some reason, one of the other
switches in the stack would then be elected manager by the management selection algorithm. It is possible
to enforce which switch will become the replacement management unit, by configuring it to have the
highest switch priority. Changing this priority in an operating stack will not affect the current stack
configuration. The priority is only used by the algorithm when a new manager needs to be elected, such as
after a power failure, or removal/failure of the current management unit.
You manage the stack from the management unit. When you connect to the console port of the
management unit, you will see the expected prompt, and you have mode-based access to all CLI
commands (For more on modes, see the CLI Modes chapter in the SFTOS Command Reference.)
If you connect to the console port on a non-management unit in a stack, the prompt is “(Unit number)>”.
The number is the one assigned to that switch. No user commands can be executed at that prompt.
Note: Unit numbers are stored in NVRAM and are persistent, even when a unit is removed from a
stack. The exceptions are if: 1) you change the unit number manually; or 2) you plug the unit into
a new stack, and it gets assigned a new unit number because a unit in that new stack already has
the same number.
Note: On a subordinate unit, the only command that shows up when you type '?' is devshell. This
is used to access a low level diagnostic shell that should only be used under the direction of a
TAC engineer. Unauthorized use of this shell could disrupt the functioning of your unit.