Upgrade Guide for Cisco Catalyst 9000 Series Switches and Smart Switches

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Upgrade Guide for Cisco Catalyst 9000 Series Switches and Smart Switches

Operational boundaries and diagnostic reference

Updated: August 1, 2026

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Outlines the operating boundaries, key terminology and provides diagnostic references for troubleshooting upgrade issues on Cisco Catalyst 9000 series switch without changing the switch state.

Use this reference to identify operating boundaries, understand image and upgrade mode restrictions, familiarize with key terminology, and utilize diagnostic references for troubleshooting Cisco Catalyst 9000 series switch upgrades without disrupting switch operations.

Scope and important boundaries

  • Always use the image, release notes, compatibility matrix, and procedures for the exact product ID and release.

  • Keep continuous console access and an out-of-band recovery path throughout the change.

  • Common Catalyst 9000 image names include cat9k_iosxe and cat9k_lite_iosxe. You must not rename an image or use one platform family’s image on another family.

  • Install mode boots packages.conf file. Legacy BUNDLE mode boots the monolithic .bin file.

  • ISSU and xFSU are eligibility-based methods, not generic alternatives to a normal upgrade. Use them only when the current exact Cisco matrix or platform guide approves the full source-to-target path and the device passes its readiness checks.

  • xFSU examples in this guide only apply to supported Catalyst 9300 series switches.

Key terminology

These are some of the common terms used in this guide:

  • Upgrade modes:

    • Install mode: where the switch boots expanded IOS XE packages through the packages.conf file.

    • Bundle mode: where the switch boots the monolithic IOS XE .bin image directly.

    • ISSU: In-Service Software Upgrade on an eligible redundant platform and exact approved release path.

    • xFSU: Extended Fast Software Upgrade, a reduced-downtime method on eligible Catalyst 9300 series switches.

  • SMU: Software Maintenance Upgrade, a release- and platform-specific patch package.

  • SSO: Stateful Switchover between an ACTIVE and a synchronized STANDBY HOT processor.

  • SVL: StackWise Virtual.

  • SWIM: Software Image Management in Cisco Catalyst Center.

  • ROMMON: the low-level bootloader or recovery environment whose prompt is switch:.

  • R0 and F0: platform locations for the route or control processor, and forwarding processor. Exact location and member syntax is platform-dependent.