Linksys SLM224G4S - Manual (Page 63)


About Switch Stacking Appendix B
24/48-Port 10/100 + 4-Port Gigabit Resilient Clustering Smart Switch with 2 Combo SFPs
It should be emphasized that when two stacks are
combined, all of the configuration information for one of
the stacks will be lost. Only the surviving master (after the
discovery/election process completes) will maintain its
configuration information.
The best practice to combine two stacks is to reset the
switches in one stack to the factory defaults and then
add the switches as described in the “Adding Units to
a Running Stack” subsection of section “Normal (Self-
Ordering) Stack).”
If one of the merged stacks had neither a Master unit
nor a Backup Master unit, then units belonging to
this group will be inserted into the stack in the exact
way as described in section “Replacing a Failed Stack
Member in a Running Stack” above. The Master will
either connect the running units to the stack using the
current numbers or will renumber them as necessary.
The process described in section ““Replacing a Failed
Stack Member in a Running Stack” applies to this case
as well.
It should be emphasized that any time two stacks are
combined into one stack, there is no way to maintain
the configuration for both sets of switches. All dynamic
information of the units that belong to the portion of
the stack that was not reelected to be the master will be
relearned.
Stacking Cable Failure
In this example, let us assume that stacking connection
cables failed and caused a stack split, as described in
section “Splitting a Stack.” When the stacking cable
connection is fixed and units are reconnected, it results in
merging two stacks as described in section “Merging Two
Stacks.”
This scenario is feasible only if the topology of the stack
is Chain topology. Single stacking cable failure will not
cause a stack split if a Ring topology is used.
Inserting Too Many Units
In this example, a user tries to insert too many units into
a stack.
All units (existing and newly inserted) are powered on
at the same time:
A Master is elected following the Master Discovery
and Master Election processes.
All other units will shut down.
NOTE:
In some extreme cases, due to a race
condition during the boot process, some of the
units might be connected and join the stack.
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A running group of units is added to an existing stack,
assuming each one of the stack groups has an elected
Master. The total of existing units and inserted units
would exceed the maximum allowed number of units
in a stack, which is 6 units for SLM224G4S, or 4 units
for SLM248G4S:
Master Detection and Master Election processes
would determine the master out of one of two
combined stacking groups.
When switches are added to a running stack,
the Unit ID Allocation and Duplicate ID Conflict
Resolution process will detect an error if too many
switches are present in the stack, and no changes
will be made to units that originally belonged
to the group managed by the newly elected
master. The original switches will retain their ID
assignments and configurations. The units that
originally belonged to the group managed by
the master that lost its master status will be shut
down.
Standalone Unit Inserted into a Running Stack
Since the unit is in standalone mode it will not participate
in a master discovery process (it will not look for a master
and will not respond to master queries). As a result it will
not join the stack but will continue to run as a standalone
manageable unit.
The ports that are connected to the other units’ stacking
links will not pass any traffic, and the master will consider
them as failed stacking links and route all traffic around
them.
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