Users Guide

50 Dell PowerConnect 55xx Systems User Guide

– When a master-enabled unit is inserted to a running stack, (or when

Master and Backup master both start at the same time), they

exchange each other’s UP TIME (the time since they powered up). If

the time difference is smaller than 10 minutes, the unit with the

lowest unit ID is elected; otherwise, the unit with the longest UP time

is elected.

– If a Master-enabled unit (with ID 1 or 2) is inserted into an

operational stack, it will be elected as a backup master.

– If a Master unit and/or a backup Master unit is removed from the

stack and the user wishes to configure one of the slave units

(numbered 3-8) to be a Master backup, the user must reset the unit’s

ID. This can be done as follows:

• If there is a Master-enabled unit in the stack: Do -

switch

renumber

2 (through CLI or GUI). This makes the nth unit a

master-enabled unit.

• If there is no Master-enabled unit in the stack: Press the reset

button on the unit to be master-enabled, and assign it a unit ID=

1 using the boot menu.

• The user can

force

a master-enabled unit to be the master unit of the

stack, even if the master election process did not select it. This is done by

switching over to the backup unit.

NOTE: Two stacking member are considered the same age if they were

inserted within a ten minute interval, for example, if Unit 2 is inserted in the

first minute of a ten-minute cycle, and Unit 1 is inserted in fifth minute of the

same cycle, the units are considered to be the same age.

NOTE: If two stack members are discovered to have the same Unit ID, only

the older unit is included in the stack. The stack continues to function and a

message is sent notifying that a unit failed to join the stack.

The Stack Master and the

Master Backup

maintain a Warm Standby. The

Warm Standby ensures that the

Master Backup

takes over for the Stack

Master if a failover occurs, so that the stack continues to operate normally.

During the Warm Standby, the Master and the

Master Backup

are

synchronized with the static configuration. When the Stacking Master is

configured, it must synchronize the

Master Backup

. The dynamic