Before starting a fast software upgrade, ensure that the software on your access switch is Cisco IOS XE Fuji 16.8.1a or later.
(This feature is supported from Cisco IOS XE Fuji 16.8.1a .)
Restrictions for Fast Software Upgrade
Fast software upgrade is not supported if the Micro Controller Unit(MCU) Field Programmable Gate Array (FPGA) upgrade is required.
Fast software upgrade is not supported if the switch is configured as Stackwise Virtual System.
Fast software upgrade is supported only on access switches with a single logical uplink connection.
Information About Fast Software Upgrade
During a software upgrade on the switch, user traffic is disrupted until the new software completely boots up. The traffic
downtime is a concern for customers running critical applications.
Cisco IOS XE 16.8.1a introduces fast software upgrade feature, which significantly reduces the traffic downtime during a software
upgrade. The fast software upgrade feature is supported on both stacking and standalone systems.
Perform a Fast Software Upgrade
Use the following procedure to perform a fast software upgrade:
request platform software package clean switch all
Clean up the previous package and provision files to free up memory for the new software.
install add file image activate fastreload commit
Install the new software image with a fast software upgrade
fastreload commit are a hidden keywords that do not appear on the CLI help.
Verify the Fast Software Upgrade
Use the following show commands to verify the software upgrade:
Run this on a stacking system to ensure that all the systems in the stack are up and running.
Run this command to ensure that the software has upgraded to the intended version.
Additional References for Fast Software Upgrade
For complete syntax and usage information for the commands used in this chapter.
Command Reference (Catalyst 9500 Series Switches)
Feature History and Information for Fast Software Upgrade
The following table provides release information about the feature or features described in this module. This table lists
only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise,
subsequent releases of that software release train also support that feature.