Cisco Catalyst 4500 series Administration Manual page 300

License Upgrade on a VSS
Note
Step 4 Install the license on the former VSS standby, the one also functioning as the active.
Note
Ensure that the VSL ports of the VSS standby are not administratively down (At this point, the the VSS
Step 5
standby is also functioning as the active, although all non-VSL ports are shutdown).
Step 6 Reboot the VSS standby.
While the VSS standby switch boots, unshut the VSL ports on the active switch. The original VSS
Step 7
standby switch boots as the VSS standby.
Step 8 When the VSS standby achieves SSO-HOT, open all shutdown ports sequentially.
Step 9 Failover the chassis to bring the VSS pair license to the correct level.
This reloads the current VSS active and forces the VSS standby to take over as the VSS active with the
new license level.
License install and subsequent VSS formation are now complete.
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)SG
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A VSS standby booting as the active does not pose a network problem because all non-VSL ports
are shutdown.
During this time, the VSS active operates without interruption.
Chapter 5 Configuring Virtual Switching Systems
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