DGS-3100 Series Gigabit Stackable Managed Switch User Manual
29
Merging Stacks
This example assumes that the user would like to merge two working stacks. This creates one stack from two separate stacks.
There are two scenarios:
If new stacking members are powered down during insertion and then powered up
•
This is identical to insert stacking members into a running stack, see
Replacing Failed Stacking-Members in a
Running Stack
. The only difference is that an additional stacking member is inserted into the stack. Therefore, for
each stacking member inserted the same process occurs.
If stacks being merged are connecting via stacking cables and, both stacks are running the following occurs:
•
If each of the joined stacks has a Stack Master, both Stack Masters s perform the
Master Discovery
process. Both
Stack Masters participate in the
Master Election
process. One Stack Master is selected as the Stack Master. The
criteria for selecting a Stack Master in a merged stack as follows:
–
Force Master
–
System Up Time
–
Lowest Unit ID
–
Lowest MAC Address
•
The process of master selection between two Stack Masters is as follows:
–
If Force Master is enabled, then the Stack Master which was forced is selected.
–
The
System Up Tim
e is measured in increments of 10 minutes The Stack Master with longest System Up Time
is selected as Stack Master.
–
If both Stack Masters have the same
Up Time,
the Stack Master with the lowest Unit ID is selected as Stack
Master.
–
If both Stack Master Unit IDs are equal the Stack Master with the lowest MAC address is selected.
–
The Master Election process assigns a dynamically allocated Unit ID Reassignment of Unit Id to the other
Stack Master and is performed by the new Stack Master. The switch is either allocated as a stack memberor
the Backup Master. There cannot be two stacking members with the same Unit ID at the process end.
–
The Stacking Master that loses the Master election process is shut down if the Unit ID was manually allocated.
It is recommended that the administrator configure the switch to
Auto Assign
mode before reconnecting the
switch to the stack.
–
When two stacks are combined, all of the configuration information for one of the stacks is lost. After the
discovery/election process is completed, only the new Stack Master maintains its configuration information,
–
If one of the merged stacks had neither a Stack Master unit nor a Backup Master, then stacking members
belonging to this groupare inserted into the stack as in
Replacing Failed Stacking-Members in a Running Stack
.
The Stack Master either connects stacking members to the stack using thecurrent Unit Ids or reallocates the
Unit IDs necessary. For more information see
Replacing Failed Stacking-Members in a Running Stack
.
If two stacks are merged into one stack, both stack configuration cannot be to maintained. All stacking member’s dynamic
information that belong to the portion of the stack that was not reelected is lost and the new Stack Master relearns the
information. .
Stacking Cable Failure
This example assumes that S
tacking Connection Cables
failed and caused the stack to split, as described in
Dividing Stacks
.
When the stacking cable connection is fixed and stacking members are reconnected, it results in merging two stacks as
described in
Merging Stacks
.
This can be occured only if the topology of the stack is
Chain
topology. Single stacking cable failure does not causes a stack
split if a
Ring
topology is used.
Inserting Excess Stacking Members
This example assumes that the user attempts to insert too many stacking members into s into a stack.
•
All stacking members (existing and newly inserted) are powered on at the same time:
–
A Stack Master is elected following
Master Discovery
and
Master Election
processes.
–
All excess stacking members are shutdown.
