Types Of Units In Stack; Backward Compatibility Of Number Of Units In Stack - Cisco SF500-24 Administration Manual

Administration: Stack Management

Types of Units in Stack

Types of Units in Stack
Cisco 500 Series Stackable Managed Switch Administration Guide Release 1.3
A stack consists of a maximum of eight units. A unit in a stack is one of the
following types:
• Master—The master unit's ID must be either 1 or 2. The stack is managed
through the master unit that manages itself, the backup unit and the slave
units.
• Backup—If the master unit fails, the backup unit assumes the master role
(switchover). The backup unit's ID must be either 1 or 2.
• Slave—These units are managed by the master unit.
In order for a group of units to function as a stack, there must be a master-enabled
unit. When the master-enabled unit fails, the stack continues to function as long as
there is a backup unit (the active unit that assumes the master role).
If the backup unit fails, in addition to the master, and the only functioning units are
the slave units, these also stop functioning after one minute. This means for
example, that if after 1 minute, you plug in a cable to one of the slave units that was
running without a master, the link will not come up.

Backward Compatibility of Number of Units in Stack

Previous versions of the device supported a maximum of four units as opposed to
the current version that supports eight units. Upgrading from earlier software
releases can be done without changing the configuration files.
When a firmware version, which does not support the hybrid stack modes is
loaded to the stack and the stack is rebooted, the stack reverts to Native Stack
mode. When device in Hybrid stack mode is loaded with firmware version that
does not support Hybrid stack mode, its system mode will revert to the default
system mode (SG500X: L3 and L2, Sx500: L2).
If a stack whose unit IDs are manually-configured, those units whose ID is greater
than 4 are switched to auto numbering.
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