Cisco SGE2000P Administration Guide - Page 33

Chapter Linksys One Ready Communications Solution 3 The Stack Master or the Backup Master Unit Remains in a Group If the Stack Master unit remains in the group, the scenario described in "Replacing a Failed Member Stack Unit in an Operational Stack" applies. If the Backup Master unit remains in the group, the scenario described in "Replacing a Failed Stack Master Unit in an Operational Stack" applies. NOTE: If the stack is split in two groups, one with the Stack Master and one with the Backup Master, both groups will function. 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. Chapter 3: Connecting the Switch 28 Stack Troubleshooting and Maintenance