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Note: Static and dynamic multi-slot trunks will flap during a hitless switchover if any
Syslog message for hitless OS upgrade and hitless switchover
The following Syslog message is generated as a result of a switchover during a
hitless OS upgrade or hitless switchover:
HITLESS-RELOAD COMPLETED - Mgmt Module in slot <slotnum> is now Active
Layer 2 hitless switchover
Platform Support: B08S and B16S chassis devices running software release
05.0.00 and later - L2, BL3, L3
Hitless switchover is a CLI-driven switchover of the active and standby
management modules without interruption to switched traffic. In software releases
that do not support hitless switchover (pre-release 05.0.00), a manual switchover
impacts the data traffic for the duration of the switchover and requires data flows to
be relearned.
This feature can be used by a system administrator, for example, to perform
maintenance on a management module that has been functioning as the active
management module. The Layer 2 functions and protocols supported by hitless
switchover are the same as those supported for hitless OS upgrade see "Layer 2
hitless OS upgrade" on page 84for a list.
Some advantages of a hitless switchover over a hitless software reload are:
v A manual switchover is quicker, since the standby module does not have to
v Switched traffic through the Ethernet interfaces on the standby management
Note: If the current active management module is physically removed from the
For a description of the events that occur during a hitless switchover, see "What
happens during a hitless OS upgrade and hitless switchover" on page 81.
For a description this feature's impact to major system functions, see "How a hitless
OS upgrade and hitless switchover impacts system functions" on page 82.
Executing a Layer 2 hitless switchover
The CLI command for executing a hitless switchover is the same as for a
switchover (non-hitless) in software releases prior to 05.0.00. See "Manually
switching over to the standby management module" on page 80.
both management modules must be reloaded with the new image. This
applies to hitless OS upgrade only. It does not apply to hitless switchover,
which does not interrupt traffic going through Ethernet interfaces on the
management modules.
of the trunk port members are on the management module.
reboot.
module is not interrupted.
chassis without first issuing the switch-over-active-role command, the
standby module will still take over the active role, but the chassis will reset
and re-initialize all components. Thus, traffic going through the system will be
interrupted.
Chapter 6. Using a redundant management module
83
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