Neither The Stack Master Unit Or The Backup Master Unit Remains In The Group - Cisco SGE2000 Reference Manual

The Master Discovery, Master Election and Unit ID Allocation & Duplicate Unit ID Conflict Resolution
processes occur with the following results:
• If the Stack Master unit remains in the split stack, the Stack Master discovers (using the Master
Discovery process) that the Master Backup unit no longer responds. The Stack Master notifies
the system administrator (using SYSLOG messages and SNMP traps) of the removed units and
ports that belong to the unreachable units and they are reported as "not present."
• If the Backup Master unit remains in the split stack, the Backup Master determines this as a case
of Stack Master failure and takes over and manages the remaining units as a stack while keeping
its previous Unit ID number. Because the Backup Master was not acting as a master prior to the
split, it initiates a topology database and ports learning process. Traffic might be halted for a
short period of time until synchronization (unit and port configuration) is completed. New units
discovered by the Backup Master notify the system administrator (using SYSLOG messages and
SNMP traps).
• The partial stacks both continue to work as they did previously, but with fewer units.
• No unit ID changes are performed in each of the partial stacks.
• If each part of the stack has a Stack Master (for example, one contains the original Stack Master,
and one contains the Backup Master), and are operating as two separate stacks, both Stack
Masters contain the same configuration and use the same IP address.
CAUTION: If both Stack Masters use the same IP Address,
problems can occur on the network, because users cannot
connect to one of the stacks through its IP address.

Neither the Stack Master Unit or the Backup Master Unit Remains in the Group

This scenario is the same as that of a failed Stack Master where no Backup Master is available. The
following concepts apply:
• Units whose ID numbers are 3 through 8 in this part of the original stack will not renumber
themselves, and will remain shut down until a master-enabled unit is connected and begins to
operate as the Stack Master. The Master Discovery process discovers that the Stack Master has
failed.
• In this group, the units lose connection with the Stack Master. Since they began as a running
stack and none of them are in factory default mode, renumbering does not occur, and even a
reset of the units will not affect unit ID assignment, because units can be renumbered only by a
Stack Master.
• No unit ID changes are performed in each one of the two groups.
NOTE: None of the units in either group will renumber
themselves.
Chapter 2: Managing Device Information
Stack Troubleshooting and Maintenance
SGE2000/SGE2000P Gigabit Ethernet Switch Reference Guide
Chapter
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