Upgrading Individual Devices in a Chassis Cluster Separately
Devices in a chassis cluster can be upgraded separately one at a time; some models allow one device after the other to be upgraded using failover and an in-service software upgrade (ISSU) to reduce the operational impact of the upgrade.
To upgrade each device in a chassis cluster separately:
During this type of chassis cluster upgrade, a service disruption of about 3 to 5 minutes occurs.