Allied Telesis AT-S63 - Manual (Page 39)

AT-S63 Stack Command Line User’s Guide
Section I: Basic Operations 39
The switches should be numbered starting with ID number 1. The switch
assigned ID number 1 will be the master switch of the stack. Any switch
can be the master switch, but it should be either the top or bottom switch in
the stack to make it easy to identify. Additionally, the switches do not have
to be numbered in the same order as their arrangement in the rack in
relation to the master switch, but they will be easier to identify if their
numbers and their order in the stack are the same.
Dynamic Module
ID Numbers
Dynamic module ID numbers are based on the MAC addresses of the
units and are automatically assigned by the management software during
the discovery process of the stack,. The module ID 1 is assigned to the
switch with the lowest MAC address. That switch becomes the master
switch of the stack. The module ID 2 is assigned to the switch with the
second lowest address, and so on.
Dynamic module ID numbers are a quick way to build a stack, but they can
be problematic, especially for stacks of more than two switches. First,
although the switches of a stack do not have to be numbered in any
special order, they will be easier to identify if they are numbered in
sequence starting with the top or the bottom unit. With dynamic module ID
numbers, there is no guarantee that will happen. For example, a stack of
five switches might be assigned these dynamic module ID numbers
starting with the top unit: 2, 4, 1, 3, 5. Such a numbering sequence could
easily lead to confusion and mistakes when you configure the devices.
Another drawback to this approach is that the assignments of the numbers
could change if you were to add or remove a switch from a stack. This, in
turn, could alter the configurations of the switches because, as explained
previously, the switches are identified by their module ID numbers in the
active configuration file on the master switch. For instance, if you were to
add a new switch whose MAC address was lower than the MAC address
of an existing switch, the module ID assignments of one or more of the
devices would change and so, in all likelihood, would their configurations.
The new switch would take on the module ID number and configuration of
a preexisting switch since it has a lower MAC address, while the displaced
switch would assume another module ID number and configuration, and
so on.
Furthermore, if a new switch’s MAC address is the lowest in the stack, it
becomes the new master switch. The entire stack would probably lose its
configuration, because the new master switch would be unlikely to have
the same stack configuration file as the previous master switch.
It should also be noted that a backup master switch is not supported in a
stack with dynamic module ID numbers. That feature is reserved for stacks
with static ID numbers.
If you do decide to use the dynamic method for assigning module ID
numbers, there is a way for controlling the ID numbers assignments by
assigning each switch a stack priority value with the SET STACK