Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 80)

50 Multi-Service IronWare Switching Configuration Guide
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How management module redundancy works
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You can install a redundant management module in slot M1 or M2 of a Brocade chassis. (By
default, the system considers the module in slot M1 to be the active management module and the
module 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.
How management module redundancy works
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
(switchover)
• System implications when a switchover occurs
Management module redundancy overview
When you apply power to a Brocade device with two management modules installed, by default, the
management module in slot M1 becomes the active module and the module in slot M2 becomes
the standby module. (You can change the default active slot from M1 to M2 using the
active-management command. Refer to
“Changing the default active chassis slot” .)
After the active and standby modules are determined, both modules boot from the source specified
for the active module. The active module can boot from the following sources:
• The flash memory on the active management module
• An Auxiliary Flash card in an Auxiliary Flash slot on the active management module.
Once the modules boot, the system compares the flash code and system-config files on the
standby module to the files on the active module. If the files are not the same, the files on the
standby module are synchronized with those on the active module.
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. Synchronizing the system-config and running-config files on
both modules allows the standby module to assume the role of active module seamlessly, if
necessary.
The interface modules are not reset, and continue to forward traffic while the standby
management module takes over operation of the system. The new now-active management
module receives updates from the interface modules and sends verification information to the
interface modules to ensure that they are synchronized. If the new active management module
becomes out of sync with an interface module, information on the interface module may be
overwritten, which can cause an interruption of traffic forwarding. An out of sync state should only
occur if there is a layer 3 topology change elsewhere in the network during the management