Stack Members; Master-Enabled Units; Unit Id Allocation - Linksys SFE2000P - Managed Ethernet Switch Reference Manual

Chapter
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SFE2000/SFE2000P Gigabit Ethernet Switch Reference Guide
The Stack Master stores a copy of the active configuration on the Backup Master. This copy is used only
if the Backup Master assumes the role of Stack Master.

Stack Members

The units assigned the Unit IDs 3 through 8 are called stack members. A stack member operates only as
a member of the stack under the direction of an operational Stack Master (or a Backup Master that has
assumed the Stack Master role). Stack members are not directly manageable and configurable, and must
be managed through the Stack Master. They do not contain any meaningful configuration information,
including their own configuration. If an operational Stack Master is not present and reachable, these
units are not functional.

Master-Enabled Units

Units that are assigned a Unit ID number of 1 or 2 are called master-enabled units. Only master-enabled
units participate in the Master Election process (see below) when they are initialized, are inserted into a
new stack, or lose connectivity with the existing Stack Master. Only master-enabled units participate in
the Master Election process and can become the Stack Master or Backup Master. (Units that are assigned
a Unit ID of 3 through 8 can only become a Stack Master or a Backup Master if they are manually
configured by the system administrator or if they are reset to the factory default mode.)

Unit ID Allocation

Units are shipped from the factory without an assigned Unit ID, and must be assigned a unique Unit ID
before they can operate as part of a stack. Unit ID numbers are assigned to units in one of two ways:
• Unit ID numbers are assigned by the system administrator, and can be changed only manually by
the system administrator.
• Unit ID numbers are allocated to a stack member unit by the Stack Master during system
initialization.
A unit that was assigned a Unit ID will usually keep this number even after it is rebooted. The Stack
Master may reallocate Unit IDs during system initialization to resolve duplicate Unit ID conflicts (see
below). Manually assigned Unit IDs cannot be changed by the Stack Master, even if there is a conflict.
Unit ID assignment or change takes effect only during system initialization and does not take place
during system runtime. Units of a stack do not have to be numbered in sequence, and can be
interconnected as long as each unit has a unique ID and at least one unit of the stack serves as Stack
Master.
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NOTE: Only the configuration file is copied. Any
dynamically-filled tables (for example, learned addresses)
are not copied from the Stack Master to the Backup Master.
If the Backup Master assumes the role of Stack Master, it
builds its own dynamic tables.
Chapter 2: