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The following prerequisites apply for performing ISSU:
The active switch must have access to the new IOS XE image or pre-load it into flash.
The switch must be running in install mode.
Non-Stop Forwarding (NSF) must be enabled.
In-Service Software Upgrade (ISSU) is a process that upgrades an image to another image on a device while the network continues to forward packets. ISSU helps network administrators avoid a network outage when performing a software upgrade. The images are upgraded in install mode wherein each package is upgraded individually.
StackWise Virtual (SVL) comprises two switches that are connected together to form one virtual swtich. SVL supports In-Service Software Upgrades. ISSU on SVL is performed either in a single step or in three-steps.
ISSU supports upgrades, downgrades, and rollbacks.
For more information on configuring Stackwise Virtual, refer Configuring Cisco Stackwise Virtual.
The following steps describe the process that is followed in performing ISSU:
Copy the new image to the standby and active switches.
Unzip the files and copy packages to both the active and standby switches.
Install the packages on the standby switch.
Restart the standby switch.
The standby switch is now upgraded to the new software.
Install the packages on the active switch.
Restart the active switch and switchover the standby to new active switch. After the switchover, the new standby switch will be up with the new software. The new software image is already installed on the new active switch, hence ISSU is completed.
This workflow involves three steps—add, activate, and commit. After activation, all switches are upgraded to new software version except that the software is not committed automatically but must be performed manually via the install commit command. The advantage of this approach is the system can be rolled back to a previous software version. The system automatically rolls back if the rollback timer is not stopped using the install abort-timer-stop or the install commit command. If the rollback timer is stopped, the new software version could be run on the device for any duration and then rolled back to the previous version.
This workflow involves only one step and helps in optimization. You cannot roll back as the upgrade is committed automatically.
For more information about ISSU release support and recommended releases, see Technical References → In-Service Software Upgrade (ISSU).
ISSU is supported only on the following SKUs of Cisco Catalyst 3850 Series Switches:
C3850-12XS
C3850-24XS
C3850-48XS
ISSU is supported only if both the switches in Stackwise Virtual are booted in install mode. (If the chassis is booted in a bundle mode, ISSU is not supported).
Upgrading hardware and software simultaneously is not supported. Only one upgrade operation can be performed at a time.
We recommend that upgrades are performed during a maintenance window.
Do not perform any configuration changes while the ISSU process is being performed.
ISSU is not supported for an upgrade from IOS XE Fuji 16.9.1 to IOS XE Fuji 16.9.2.
Downgrade with ISSU is not supported.
While performing ISSU from Cisco IOS XE Fuji 16.9.x to Cisco IOS XE Gibraltar 16.12.x, if interface-id snmp-if-index command is not configured with OSPFv3, packet loss can occur. Configure the interface-id snmp-if-index command either during the maintenance window or after isolating the device (by using maintenance mode feature) from the network before doing the ISSU.
The device must be booted in the install mode.
Ensure that the SVL link is up.
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
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| Step 2 |
install add file { ftp: | tftp: | flash: | disk: *.bin } actvate issu commit |
Automates the sequence of all upgrade procedures that include downloading the images to both the switches and expanding into packages, and upgrading each switch as per the procedure.
|
The device must be booted in the install mode.
Ensure that the SVL link is up.
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
||
| Step 2 |
install add file { ftp: | tftp: | flash: | disk: *.bin } Example: |
This command downloads the image into the bootflash and expands it on both the switches. |
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| Step 3 |
install activate issu Example: |
On executing this command, the following sequence of events occurs:
|
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| Step 4 |
install commit Example: |
The commit command performs the necessary clean up, enables the new software as permanent (removing the older version of the software) and stops the rollback timer. Any reboot after the commit will boot with new software.
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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.
Use the Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.|
Feature Name |
Release |
|---|---|
| ISSU on StackWise Virtual |
Cicso IOS XE Fuji 16.9.2 |
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