This guide covers the Cisco Nexus NX-OS software upgrade process in a practical, step-by-step manner — including rollback and recovery scenarios. The goal is to minimize service disruption and ensure the device can always be recovered in case of failure.

Most upgrade failures are not caused by the upgrade itself — they are caused by skipping preparation steps. This guide treats preparation as seriously as execution.

Cisco Nexus NX-OS Upgrade Process

For out-of-band access during upgrade failures, see: The Backdoor of the Network: Next-Gen Console Server Architecture

1. Pre-Upgrade Checks

Before starting the software upgrade, you must complete the preparation steps below. This phase is the most commonly skipped — and the most common source of problems.

Configuration Backup

  • Take a backup of the current configuration before anything else.
  • Store the backup on your own computer or an external location such as FTP/SFTP — not on the switch itself.
  • If the upgrade fails or a rollback is needed, this backup is critical.

Verify Switch Model and Current Software Version

Check the switch model and the running NX-OS version with these commands:

show version
show module
show inventory

These outputs are required to select the correct NX-OS image, determine the upgrade path, and verify hardware compatibility.

2. Download the Software Image

  • Download the correct NX-OS image for your switch model from Cisco’s official portal: https://software.cisco.com/download/home
  • A valid Cisco account with the appropriate entitlements is required.
  • After downloading, note the MD5 hash value — you will need it to verify file integrity after transfer.

MD5 verification confirms the file was not corrupted during download. This step is not optional.

3. Verify the Upgrade Path

A direct upgrade from your current NX-OS version to the target version is not always supported. Some version combinations require intermediate steps.

Use Cisco’s official tools to verify:

  • Nexus Upgrade Matrix Tools
  • Nexus 9000 / 3000 Series
  • Nexus 7000 Series

If multiple upgrade steps are required, download all intermediate images before starting the process.

4. Copy the Software File to the Switch

Option A: FTP Transfer

FTP is one of the most common methods. Note that NX-OS images can be close to 2 GB, so transfer time depends on network speed.

Example:

copy ftp://user1:Qazwsx@10.10.10.5/nxos.9.3.10.bin bootflash:

If multiple VRFs are configured on the Nexus, you will be asked which VRF to use for the transfer. Since the management interface typically uses the management VRF, select management VRF.

USB transfer is my preferred method when:

  • No FTP server is readily available
  • You have time constraints
  • You want to avoid any network transfer risk
copy usb1:nxos.9.3.10.bin bootflash:

Ensure the USB filesystem format is supported by the Nexus device before proceeding.

MD5 Hash Verification

After the transfer, verify file integrity:

show file bootflash:nxos.9.3.10.bin md5sum

The output must exactly match the MD5 hash from the Cisco download portal.

5. Run the Upgrade

Once all checks are complete, start the upgrade:

install all nxos bootflash:nxos.9.3.10.bin
  • The switch automatically saves the current configuration before installation.
  • You will be prompted for confirmation before the reboot.
  • After confirmation, the device reboots and the upgrade begins.

Upgrade duration varies depending on the device model and software size.

6. Rollback and Recovery Scenarios

Nexus Upgrade Rollback and Recovery Path

ROMMON Mode Entry

If the installation fails or the device does not boot:

  • During device startup, press CTRL + L or CTRL + C via console connection to enter ROMMON mode.

Boot via TFTP from ROMMON

set ip 10.10.10.2 255.255.255.0
set gw 10.10.10.1
cmdline recoverymode=1
boot tftp://10.10.10.2/tftpboot/nxos.9.3.10.bin
init system
reload-nxos

Boot via USB from ROMMON

boot usb1:nxos.9.3.10.bin bootflash:
set ip 10.10.10.2 255.255.255.0
set gw 10.10.10.1
cmdline recoverymode=1
boot usb1:nxos.9.3.10.bin
init system
reload-nxos

After booting from TFTP or USB, verify and correct the boot settings:

show boot

configure terminal
  boot nxos bootflash:/nxos.9.3.10.bin

Critical Warning

During the software upgrade:

  • Do not interrupt the network connection
  • Do not interrupt the power supply

Either condition can render the device unrecoverable without physical intervention.

Architecture & Operations

Practical Engineering