Dell PowerConnect B-RX BigIron RX Series Configuration Guide v02.8.00 - Page 101

Chapter Using a Redundant Management Module 3 How management module redundancy works You can install a redundant management module in slot M1 or M2 of the BigIron RX Series devices. By default, the system considers the module installed in slot M1 to be the active management module and the module installed in slot M2 to be the redundant or standby module. If the active module becomes unavailable, the standby module automatically takes over management of the system. This chapter describes the redundant management module, how it works with the active module, and how to configure and manage it. This section explains the following: • How management module redundancy works under normal operating conditions. • Events that cause a standby management module to assume the role of the active module and how the switchover occurs as a result of each event. • Implications that you should be aware of if a switchover occurs. Management module redundancy overview When you power on or reload a BigIron RX Series device with two management modules installed, by default, the management module installed in slot M1 becomes the active module and the module installed in slot M2 becomes the standby module. (You can change the default active slot from M1 to M2 using the active-management command. For information about performing this task, refer to "Changing the default active slot" on page 29.) After the active and standby modules are determined, both modules boot from the source specified for the active module. The active management module can boot from the following sources: • The active management module's flash memory. • A PCMCIA flash card inserted in one of the PCMCIA slots in the active management module's front panel. After the modules boot, the active module compares the standby module's flash code and system-config file to its own. If differences exist, the active module synchronizes the standby module's flash code and system-config file with its own. During normal operation, the active module handles tasks such as obtaining network topology and reachability information and determining the best paths to known destinations. The active module also monitors the standby module. The standby module functions in an active standby mode. Configuration changes made from the CLI to the active management module are also written to the standby management module even if they are not written to flash memory. Keeping the system-config and running-config files on both modules synchronized allows the standby module to assume the role of active module seamlessly if necessary. BigIron RX Series Configuration Guide 25 53-1002253-01