Chapter 6. Using A Redundant Management Module; How Management Module Redundancy Works; Management Module Redundancy Overview - IBM s-series Installation And User Manual

Chapter 6. Using a redundant management module

You can install a redundant management module in the B08S and B16S. By default,
the system considers the module installed in the lower-numbered slot to be the
active management module, and the module installed in the higher-numbered slot
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 chapter provides the following information:
v How management module redundancy works
v Optional management module redundancy configurations that you can perform
v Hitless management features (hitless Layer 2 switchover and hitless Layer 2 OS
v How to manage and monitor the redundancy feature

How management module redundancy works

This section explains the following:
v How management module redundancy works under normal operating conditions.
v Events that cause a standby management module to assume the role of the
v Implications that you should be aware of if a switchover occurs.

Management module redundancy overview

When you power on or reload a B08S or B16S with two management modules
installed, by default, the management module installed in the lower-numbered slot
becomes the active module and the management module in the higher-numbered
slot becomes the standby module. (You can change the default active slot using the
set-active-mgmt command. To read additional information about performing this
task, see "Changing the default active chassis slot" on page 78.
After the active and standby modules are determined, both modules boot from the
source specified for the active module. The active management module boots from
the active management module's flash memory.
After the modules boot, 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. 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.
During a switchover, the standby management module takes over the active role
and re-initializes all the interface modules in the system that are not CLI-disabled by
the administrator. This may cause a brief interruption of the traffic forwarding.
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upgrade)
active module and how the switchover occurs as a result of each event.
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