Cisco SFE2000 Administration Guide - Page 31

Chapter Linksys One Ready Communications Solution 3 manually assigned Unit ID, the Stack Master cannot change it. If the incoming unit cannot be assigned an available Unit ID, then it is shut down and is not joined to the stack. 3. The Stack Master performs unit and port configuration for the incoming unit. • Any configuration information that is relevant to the number assigned to the incoming unit is applied by the Stack Master. For example, if the incoming unit is assigned the same Unit ID of the unit it replaced, then when possible, it receives the same configuration as the failed unit. • If the incoming unit is identical to the replaced unit, the entire configuration of the replaced unit is applied to the incoming unit and the stack returns to the state it was in before unit failure. If the incoming unit is not identical to the unit that failed, the Stack Master applies the configuration in the following manner: • If a 24-port unit replaces a failed 48-port unit, the ports of the incoming unit are configured according to the configuration of the first 24 ports of the failed unit. NOTE: The configuration of all 48 ports of the failed unit is kept in memory, even though the first 24 are currently applied. If, in the future, a 48 port unit is inserted and assigned the same Unit ID, it is configured the same as the original failed 48-port unit. • If a 48-port unit replaces a 24-port unit, then the first 24 ports of the incoming unit are configured according to configuration of the ports of the failed unit. The remaining ports of the incoming are configured according to the default settings. • If the units have uplink ports, then the first uplink port of the incoming unit is configured according to the configuration of the first uplink port of the failed unit. Replacing a Failed Stack Master Unit in an Operational Stack When the Stack Master unit fails, the stack Backup Master, using the Master Discovery process, discovers that the Stack Master unit no longer responds. The Backup Master takes over as the Stack Master. The Backup Master (now the Stack Master) directs all other stack members to route unit-to-unit traffic around the failed unit using the ring topology of the Chapter 3: Connecting the Switch 25 Stack Troubleshooting and Maintenance