Cisco SGE2000 Administration Manual page 35

Linksys One Ready Communications Solution
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If the incoming units are powered off, follow the procedures described in "Building a New
Stack" in the "Building Automatically-Configured Stacks" or "Building Manually-Configured
Stacks" sections. Repeat the process for each unit inserted into the stack.
If both stacks to be merged are running (for example, you are connecting the stacking cables
of two stacks), the following occurs:
• If each of the joined stacks has a Stack Master unit, both Stack Master units perform the
Master Discovery process and participate in the Master Election process. One of the
Stack Master units is selected as the Stack Master unit for the merged stack. The criteria
for choosing the Stack Master are as follows:
- Force Master: If Force Master is enabled, the unit that is configured as the forced
unit is selected as the Stack Master.
- System Up Time: Up time is measured by quantities of 10-minute intervals. If the
number of 10 minute intervals is higher for one of the units, this unit is selected
as the Stack Master.
- Lowest Unit ID: If both units have the same up time (measured in intervals of 10
minutes), the unit with the lowest unit ID is selected as the Stack Master.
- Lowest MAC: If both Master unit ID numbers are equal, the unit with the Lower
MAC address is chosen as the Stack Master.
The Stack Master unit that loses its "mastership" in the Master Election process is
renumbered if the unit ID was dynamically allocated. The new Stack Master allocates it a
new number and configures it as a stack member or a Backup Master. It will be shut
down if the unit ID was manually allocated. We recommend that the administrator
configure the unit to receive an auto-assigned Unit ID before reconnecting it to the stack.
NOTE: There will never be two units with the same Unit ID
at the end of the merge.
When two stacks are combined, all of the configuration information for one of the stacks
is lost. Only the surviving Stack Master (after the discovery and election processes are
complete) maintains its configuration information.
Chapter 3: Connecting the Switch
Stack Troubleshooting and Maintenance
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