Alcatel OS6850-P48 User Guide - Page 169

Managing OmniSwitch 6850/6850E Series Stacks Roles Within the Stack Primary Secondary 1 A stack of two switches is operating normally. The stack consists of a primary module and a secondary module. (The software on both elements in the stack is synchronized.) ! Offline Secondary Offline Primary 2 The primary management module fails or is taken offline (e.g., powered off or rebooted by the user). 3 The switch operating as the secondary management module immediately takes over the primary role. It is at this point essentially operating as a stand-alone switch. Secondary Primary 4 If the switch that previously failed or was taken offline comes back online, it will assume the secondary role in the stack. Redundant Management Module Failover (Two Switches) OmniSwitch 6850/6850E Series Hardware Users Guide June 2011 page 6-7