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3. The active management module synchronizes the standby management module
4. The Layer 2 control protocols on the standby management module converge.
5. The standby management module takes over the active role.
6. The old active management module resets and reloads with the same software
7. The switch is now operating on the new software image. The management
Note: The events described above occur internally and do not create or affect the
How a hitless OS upgrade and hitless switchover impacts system
functions
The following table highlights the implications of a hitless OS upgrade or hitless
switchover to the system's major functions.
Note: All traffic going through Ethernet interfaces (if present) on the management
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Ethernet Switch s-series Installation and User Guide
with all the information required to take over the active role.
This process takes approximately 70 seconds.
image running on the current active management module.
module that was initially configured as the standby management module is now
the active management module and the management module that was initially
configured as the active management module is now the standby.
external network topology.
Table 25. Hitless OS upgrade and hitless switchover impacts
Traffic Type
Layer 2 switched traffic, including
unicast and multicast
Layer 3 routed traffic, including
unicast and multicast
Management traffic
Security features
modules will be interrupted during a hitless OS upgrade. This is because
Impact
Layer 2 switched traffic is not impacted during a
manual switchover. All existing switched traffic flows
continue uninterrupted. New switched flows are not
learned by the switch during the switchover process
and are flooded to the VLAN members in hardware.
After the new active management module becomes
operational, new switched flows are learned and
forwarded accordingly. The Layer 2 control protocol
states are not interrupted during the switchover
process.
Layer 3 routed traffic is briefly interrupted during the
manual switchover process. The traffic will converge
to normalcy after the new active CPU becomes
operational.
All existing management sessions (SNMP, TELNET,
HTTP, HTTPS, FTP, TFTP, SSH etc.), are briefly
interrupted during the switchover process. All such
sessions are terminated and can be re-established
after the new active CPU takes over.
All security features other than configured ACLs are
not hitless. Configured ACLs will continue to operate
in a hitless manner, meaning the system will
continue to permit and deny traffic during the
switchover process.
All other security features are briefly interrupted
during the switchover process and will return to
normalcy after the new active management module
is operational.
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