Cisco SGE2000 - - Gigabit Switch Administration Manual page 29

Managing Device Information
Managing Stacking
Cisco Small Business SFE/SGE Managed Switches Administration Guide
For example:
•
If there are two or more Master-enabled units and only one of them has
been assigned as Force Master, the Force Master unit is the winner of step 1
and therefore the winner of the Master Election.
•
If there are two or more Master-enabled units that have been assigned as
Force Master, then the Master Election proceeds to step 2, where the
running times of the Force Master units are compared. If there is a winner at
step 2, then the winner of that step also wins the Master Election and
becomes the Master unit.
•
If there is no winner of step 2, the election proceeds to step 3. Only
contending units that have succeeded in tieing in previous steps remain
contenders. If there is a single unit with Unit ID=1, then that unit wins step 3
and the Master Election.
•
If there are two or more units assigned to Unit ID=1, then the election
proceeds to step 4. There is always a winner of step 4 because MAC
addresses are unique.
Master Election Backup Unit Selection Rules
The candidate that wins the Master Election becomes the Master unit. If there is a
single runner-up unit, that unit becomes the Backup unit. If there is a tie for the
runner-up position, then the tie is resolved by applying the Unit ID Conflict
Resolution rules.
Recommended Procedures for Building a Stack
To avoid possible Unit ID conflicts and device shutdowns, Cisco recommends that
the following procedures be adopted when configuring and managing stacks:
•
A stack should be initially configured by connecting all stack members in
factory default mode.
•
If there is a preference for assigning specific Unit IDs to specific devices, then
the stack should be built by connecting and booting the devices, in factory
default mode, one by one in the desired Unit ID order that they will be assigned
in the stack. That is, the device that will be the Master unit should be powered
on first. After it boots and is automatically numbered (as Unit 1) it becomes the
Master unit. The unit that will become the Backup unit is then connected to the
Master unit and powered on. It is assigned to be Unit 2 by the Master unit and
becomes the Backup unit. The next unit is then connected to either the Master
(Unit 1) or Backup (Unit 2) unit and then powered on. It is assigned to be Unit 3
by the Master unit. Subsequent units are joined to the stack by connecting
2
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