Cisco catalyst 3850 прошивка

In-Service Software Upgrade (ISSU) on Catalyst 3850, Catalyst 9000 series switches

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The objective of this document is to help understand the steps involved in performing ISSU on Catalyst 9000 and Catalyst 3850 series switches.

What is ISSU

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.

ISSU is supported on all Catalyst 3850 and Catalyst 9000 series supporting Stackwise-Virtual and also on Catalyst 9400 / 9600 stand-alone chassis with dual supervisors.

StackWise Virtual (SVL) comprises two switches that are connected together to form one virtual switch. SVL supports In-Service Software Upgrades.

ISSU supports upgrades, downgrades, and rollbacks.

Supported Platforms and Release Support Matrix

Before proceeding with ISSU, check if the platform actually supports ISSU. Also verify if ISSU is supported between current code and target code. Mode details on the supported platforms and ISSU compatibility matrix can be found here — ISSU Support between Releases

Pre-Requisites before ISSU

Note: The example in this document is based on Cisco Catalyst 9500 switches configured as Stackwise-Virtual. The steps are applicable to Cat9400 / Cat9600 stand-alone chassis with dual supervisor engines & also for Catalyst 3850 / Catalyst 9000 devices configuerd as Stackwise-Virtual.

1. Check current Code Version

2. Check the boot mode

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. You will see errors like below if you try to run ISSU when the switches are running in BUNDLE mode.

3. Check if there is sufficient available memory on flash

Ensure that you have at least 1GB of space in flash to expand a new image. Clean up old installation files in case of insufficient space using «install remove inactive» command.

4. Check if switches are in SSO mode

5. Check if Auto-Boot is enabled

If Auto-Boot is not enabled, this can be changed as below:

6. Check the current ISSU and Install States.


7. Copy the new image to be upgraded / downgraded.

It is sufficient to copy the image only to the Active chassis (incase of Stackwise) or the Active supervisor (incase of Cat9400 dual SUP).

ISSU Workflows — Actual Upgrade

Once all the pre-requisites are verified, you can proceeed with the actual upgrade using one of the methods below:

  • 1-Step Work Flow (only one step and does not support roll back)
  • 3-Step Work Flow (involves 3 steps and supports roll-back incase of failure)

1-Step Work Flow

  • This workflow involves only one step and helps in optimization.
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NOTE: You cannot roll back as the upgrade is committed automatically. Proceed to 3-Step Work Flow if looking to roll back.

Proceed to after ISSU is completed.

3-Step Work Flow

  • 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 auto-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.

STEP 1: Install_add

This command downloads the image into the bootflash and expands it on both the switches.

STEP 2: Install_activate

On executing this command, the following sequence of events occurs:

(i) A rollback timer is started. If the rollback timer expires, the system rolls back to the same state before the start of the ISSU. The rollback timer can be stopped by using the install auto-abort-timer stop command. ISSU can be rolled back using install abort issu command.

(ii) The standby switch is provisioned with the new software and it reloads with the new software version. Next, the active switch is provisioned with the new software and it reloads. The standby switch with the new image now becomes the active switch and the old active switch becomes the standby.

At the end of this procedure, both the switches run with the new software image.

At the end of Activate state, check the ISSU states.

STEP 3: Install_commit

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.

Post ISSU Checklist

Once ISSU is successfully completed,

  • Check if both switches are running on the new software.
  • Check » show issu state detail» output to be clean and not showing any ISSU in progress.
  • Check » show install issu history » output for ensuring successful ISSU operation (NOTE: Command available only starting 16.10.1 release)
  • It is recommended to give enough soak time in the new software before enabling any new feature.

Action on ISSU Failure

  • If ISSU fails, it is expected that auto-abort will recover the system back to initial state (older image). However, if this fails as well, manual recovery of the chassis is expected.
  • During manual recovery, check if both active and standby are running the older image (if not — recover the individual chassis)
  • After ensuring both chassis are running the old image, run » install remove inactive » to remove any unused image packages.
  • Once both chassis are running the old software, manually clean all the internal states of ISSU operation. (Refer below on how to clean the internal ISSU states)

1. Abort ISSU

  • In the 3-Step Work Flow, during the activate ISSU process, if the abort-timer expires, system will auto-abort to older image.

Note: If the standby does not reach SSO during abort, manual abort is required. Also, if for any reason you wish to abort the ISSU in between, manual abort is required.

2.Cleaning ISSU State

If ISSU upgrade/downgrade/abort/auto-abort is not successful, manual clean up of ISSU internal states is required.


Upgrade, Recover, and Manage Catalyst 3850 Series Switch

Available Languages

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Bias-Free Language

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.



This document describes the upgrade process for Cisco Catalyst 3850 Series Switches and offers disaster recovery techniques in the case of a software or boot failure.



Cisco recommends that you have knowledge of these topics:

  • TFTP
  • FTP
  • Experience with Cisco IOS ® XE software upgrades

Components Used

The information in this document is based on the Cisco Catalyst 3850 Series Switch that runs Cisco IOS® XE Versions 03.03.00 and later. The examples in this document use a stacked solution; however, the same commands can be run on a standalone switch.

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The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Note: In order to download Cisco IOS® XE images from the Cisco website, you must have a valid Cisco Connection Online (CCO) account with entitled credentials. Cisco does not offer a free TFTP/FTP solution. Install and configure the TFTP/FTP before you begin.

Install Versus Bundle Mode

The Cisco Catalyst 3850 Series Switch has two modes of operation: INSTALL and BUNDLE.

There are minor differences between the two modes. Review the configuration guide for more details.

Cisco recommends that the INSTALL mode is used during operation because it allows for a more complete set of features and requires fewer resources upon boot. This document provides a brief overview of each mode for reference.

Install Mode

This is the default mode for the switch. The INSTALL mode uses a package-provisioning file named packages.conf in order to boot the switch. In addition, there are a number of .pkg files in the flash.

Cisco recommends that you do not alter these files unless directed by a Cisco Technical Assistance Center (TAC) engineer.

Bundle Mode

If you are comfortable with the use of traditional monolithic IOS® images in order to boot the switch, then the BUNDLE mode is likely familiar.

The BUNDLE mode consumes more memory than the INSTALL mode because the packages are extracted from the Bundle and copied to the RAM.

Verify the Mode

In order to verify the mode, enter the show version command:


In order to begin the upgrade process, download the IOS® XE .bin file from the Cisco web site and place it in the flash of your active switch. The process that is used in order to copy the file to the switch is not covered in this document.

When you copy the .bin file to a single switch, the install process replicates the file to the other switches in the stack. Once the file is present, enter this command:

Note: There are many options available after each command; however, in this example a basic upgrade is run.

When the upgrade process begins, the switch pushes the .bin file to the stack member peers.

After all of the members receive the .bin file, it is automatically expanded to the flash.

Next, the switch lists a summary of the files that are marked for both removal and addition to the packages.conf pointer file.

Lastly, the packges.conf file is updated and committed.

Verify that the update process is properly completed upon reload.

Flash Cleanup

Residual files remain in the flash from previous versions. To clean up the residual files, enter the software clean command instead of a manual deletion of the files. This purges the files that the switch no longer needs.

Note: This command also deletes the .bin file that is used in order to install the new IOS software. It is important to remember that once it is extracted, you no longer need it.

The next two sections provide examples of how the flash appears before and after the software clean command is used.

Before Flash Cleanup

After Flash Cleanup

Here is the output from the show flash command after the flash cleanup:

Auto-Upgrade Feature for Catalyst 3850 Series Switches

One scenario in which a new switch is introduced into a current stack of Catalyst 3850 Series Switches is when a new switch is purchased in order to expand the number of usable ports in the stack.

In order to successfully add a new switch to a stack, you must ensure that the same software version is run on the new switch. Prior to IOS® XE Version 3.3.1, the only way to ensure that the versions match is to stage the new switch prior to introduction into the stack.

The Catalyst 3850 Series Switches include a feature called Auto-Upgrade. The goal of this feature is to ensure that a newly added switch is automatically provisioned by the stack members with the correct IOS® XE version.

Note: Auto-Upgrade is disabled by default and is not available in BUNDLE mode.

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In order to use the Auto-Upgrade feature, add the software auto-upgrade enable command into the configuration of the current stack. This ensures that any newly added stack members are automatically upgraded.


Once the switch is stacked and booted, there is an indication that there is a mismatch in versions and the new member does not fully join the stack.

To watch the SYSLOG as the switch attempts to join, notice that the Auto-Advise feature alerts that the newly added switch runs a different software version and mode.

Note: For this example, the new switch runs IOS® XE Version 3.2.2 in BUNDLE mode.

Once the newly joined member is fully booted, a mismatch is detected:

Enable Auto-Upgrade Feature

In Global Configuration mode, enter the software auto-upgrade enable command. This enables the feature for any new switches that join the stack.

Reload the newly added switch only; a full stack reload is not necessary. In this case, the newly added switch is switch 3, so the reload slot 3 command is entered.

Tip: The slot mentioned in these commands designates the switch in the stack (slot 1 = switch 1).

The switch reloads in the background momentarily. Then, you see this:

The conversion from BUNDLE to INSTALL mode occurs, followed by a reload:

After the reboot, the upgrade continues:

Another reload is performed automatically. Once the switch boots up, it successfully joins the stack with the correct IOSXE version and software mode.


Use the show switch and show version commands in order to verify that the upgrade process is completed properly:

Recover from a 3850 Series Switch Boot Failure

This section describes possible recovery methods for a 3850 Series Switch boot failure, such as a corrupt boot image, a corrupt packages.conf file, or missing files.

Note: Ensure that you have knowledge of the two possible boot modes, INSTALL and BUNDLE, before you continue.

Standard Recovery Methods

This section describes the two standard methods that are used in order to recover from a Catalyst 3850 Series Switch boot failure.

USB Recovery

The 3850 Series Switches have a USB port on the front that is used for console access. This USB port is also used with flash drives for image backup and recovery.

If stuck at the switch: prompt with a corrupt image or .conf file, boot to a file that is stored on the USB drive or copy an image from the USB to internal flash. Complete these steps in order to recover from the boot failure:

    Verify that the flash drive is recognized and the .bin file exists:

Boot to the USB image:

Note: This process boots the switch into BUNDLE mode.

Tip: You can also copy the .bin file from usbflash0: to flash:, and point the boot statement towards internal flash.

Corrupt File Recovery

There are instances when the packages.conf calls files no longer exist in flash. You can manually boot an image from the switch: prompt file; however, upon reload it calls the packages.conf file again and fails to boot.

If this occurs, Cisco recommends to back up the current packages.conf file and rename it or delete it. This process is mandatory, as the next step fails if a .conf file already exists.

Once the .bin file is extracted, a new packages.conf file is created. Complete these steps in order to recover from a corrupt packages.conf file:

    Once booted (in BUNDLE mode), verify the files in the flash:

Copy or rename the current packages.conf file:

Expand the bundle in order to create a new packages.conf file:

Verify the boot:

Reload the switch:

Emergency Recovery

If the previous recovery methods fail, the 3850 Series Switches have a trap door method to use in order to recover the system. A terminal must be connected to the management port of the switch that runs a TFTP server. Download a valid image file from CCO and store it in the root of the TFTP server.

It is likely that the switch is stuck at the switch: prompt. However, if you are in a boot loop, use the Mode button on the front of the switch in order to break the cycle: hold the button for approximately ten seconds, and the switch breaks the cycle and stops at the switch: prompt.

Complete these steps in order to perform an emergency recovery:

    Set the switch IP address:

Set the default gateway:

Ping the terminal that contains the TFTP server in order to test the connectivity:

Verify that the emergency files exist in the switch file system: