Which component becomes unavailable for a maximum of 80 seconds during a nondisruptive Cisco NX-OS upgrade?

While supervisor modules are involved in the upgrade and switchover, the control plane is the specific functional component that becomes unavailable, rather than the hardware module itself.

The default VSAN is a logical Fibre Channel construct, and its availability is tied to the Fibre Channel control and data plane, but it's not the primary component that goes unavailable during a general NX-OS upgrade.

During a nondisruptive Cisco NX-OS upgrade (ISSU), the data plane forwarding typically continues without interruption, but the control plane, which manages routing protocols, management interfaces, and system processes, undergoes a temporary restart or switchover, resulting in its unavailability for a brief period, often cited as a maximum of 80 seconds.

A nondisruptive upgrade explicitly aims to ensure the data plane remains available for traffic forwarding, so it does not become unavailable.