D-Link DES-3528 - xStack Switch - Stackable Reference Manual page 32

xStack® DES-3528/DES-3552 Series Layer 2 Stackable Fast Ethernet Managed Switch Web UI Reference Guide
Figure 2-18 Switches stacked in a Duplex Chain
Within each of these topologies, each switch plays a role in the Switch stack. These roles can be set by the user per
individual Switch, or if desired, can be automatically determined by the Switch stack. Three possible roles exist when
stacking with the DES-3528/DES-3552 Series.
NOTE: Only ports 27 and 28 of the DES-3528/DES-3552 Series, or ports 51 and ports 52 of DES-
3552/DES-3552P support stacking. The other ports cannot be used for stacking. For a stacking
disabled device, ports 27 and 28 of the DES-3528 Series, or ports 51 and ports 52 of DES-
3552/DES-3552P can be used as normal GE ports.
Primary Master – The Primary Master is the leader of the stack. It will maintain normal operations, monitor operations
and the running topology of the Stack. This switch will also assign Stack Unit IDs, synchronize configurations and
transmit commands to remaining switches in the switch stack. The Primary Master can be manually set by assigning
this Switch the highest priority (a lower number denotes a higher priority) before physically assembling the stack, or it
can be determined automatically by the stack through an election process which determines the lowest MAC address
and then will assign that switch as the Primary Master, if all priorities are the same. The Primary master are physically
displayed by the seven segment LED to the far right on the front panel of the switch where this LED will flash between
its given Box ID and 'H'.
Backup Master – The Backup Master is the backup to the Primary Master, and will take over the functions of the
Primary Master if the Primary Master fails or is removed from the Stack. It also monitors the status of neighboring
switches in the stack, will perform commands assigned to it by the Primary Master and will monitor the running status
of the Primary Master. The Backup Master can be set by the user by assigning this Switch the second highest priority
before physically assembling the stack, or it can be determined automatically by the stack through an election process
which determines the second lowest MAC address and then will assign that switch as the Backup Master, if all
priorities are the same.
Slave – Slave switches constitute the rest of the switch stack and although not Primary or Backup Masters, they can
be placed into these roles when these other two roles fail or are removed from the stack. Slave switches perform
operations requested by the master, monitor the status of neighbor switches in the stack and the stack topology and
adhere to the Backup Master's commands once it becomes a Primary Master. Slave switches will do a self-check to
determine if it is to become the Backup Master if the Backup Master is promoted to the Primary Master, or if the
Backup Master fails or is removed from the switch stack. If both Primary and Backup masters fail, or are removed from
the Switch stack, it will determine if it is to become the Primary Master. These roles will be determined, first by priority
and if the priority is the same, the lowest MAC address.
Once switches have been assembled in the topology desired by the user and powered on, the stack will undergo three
processes until it reaches a functioning state.
Figure 2-19 Switches stacked in a Duplex Ring
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