Management and Configuration Guide K/KA/KB.15.15

When switchover will not occur
There are some events for which a switchover is not triggered:
• When a boot system command is executed
• When the Clear button on the System Support module is pressed
• When management module redundancy is disabled, unless there is a hardware failure and
the system is rebooted.
When a management module crashes while the other management module is rebooting
If the uncommon situation occurs where the active management module (MM1) is trying to reboot
and the standby management module (MM2) also crashes, the switch attempts to recover from the
crash and eventually the standby management module becomes the active management module
if it passes self-test. However, traffic can be disrupted for as long as five minutes before the newly
active management module (MM2) has finished rebooting.
Hotswapping out the active management module
You can hotswap out the active management module and have switch operations taken over by
the standby management module by following the correct shutdown procedure on the active module
using the MM Shutdown button. When the MM Shutdown button is pressed, any file synchronization
in progress completes before the shutdown begins, and then a graceful shutdown of that
management module occurs.
When the standby module is not available
If you have disabled management module redundancy with the no redundancy
management-module command, or the standby module failed selftest, the Dwn LED does not
turn green to indicate it is OK to hotswap out the active management module.
NOTE: If you remove the active management module without pressing the MM Shutdown button,
any files that may have been in the process of synchronizing will not finish synchronizing to the
standby module and all file transfer is aborted.
Hotswapping in a management module
If another management module is hotswapped in while there is an active management module
booted up, the newly hotswapped management module becomes the standby module.
No negotiating is needed as to which module becomes the active management module, because
there is already a functioning active management module. However, the following conditions must
be met to determine if the hotswapped module can become a standby management module:
• The hotswapped module must pass selftest
• Management module redundancy is not administratively disabled (using the no redundancy
management-module command.) If the active management module's config file has
redundancy administratively disabled, the hotswapped management module goes into "offline"
mode.
In nonstop switching mode—The active management module's files and features are synced with
the standby management module. Heartbeats are sent back and forth, and the standby management
module is ready to quickly take over in the event of a switchover or a failure on the active
management module.
In warm-standby mode—The standby management module partially boots up and heartbeats are
sent back and forth with the active management module.
Software version mismatch between active and hotswapped module
If the software version in the hotswapped module does not match the software version in the active
module, the following occurs:
1. The active module sends the primary and secondary images in flash to the hotswapped module.
Hotswapping management modules 487