SystemEXEC

show version

Displays system hardware and software information including version, uptime, and hardware details.

Overview

The 'show version' command is a fundamental diagnostic tool on Cisco NX-OS devices, providing a concise summary of the system's hardware and software state. It is typically the first command executed when logging into a Nexus switch to verify the platform, operating system version, and uptime. The command displays critical information such as the NX-OS version, BIOS version, system image file location, hardware model, serial number, memory size, and the reason for the last system reset. This data is essential for inventory management, software upgrade planning, and troubleshooting system stability issues. On Cisco NX-OS, 'show version' also includes the kickstart image and bootflash details, which are specific to the modular architecture of Nexus switches. Unlike Cisco IOS, where 'show version' focuses on IOS version and hardware, NX-OS output is more structured and includes separate sections for software and hardware. In troubleshooting workflows, 'show version' helps verify that the correct software version is running, check if the system has been recently rebooted (which may indicate a crash), and confirm hardware compatibility when adding new modules. It is also used to gather serial numbers for support cases and to ensure that the device meets minimum requirements for features like VXLAN or MPLS.

Syntax·EXEC

show version

When to Use This Command

Verify the current NX-OS software version before upgrading or downgrading.
Check system uptime and last reload reason for troubleshooting stability issues.
Identify hardware model, serial numbers, and memory for inventory or capacity planning.
Confirm boot variable and kickstart image for post-upgrade verification.

Parameters

Parameter	Syntax	Required	Description
module	show version module <slot>	Optional	Displays version information for a specific module (line card) in the chassis. The slot number identifies the module location. Useful for verifying individual module software and hardware versions.

Command Examples

Basic show version output

show version

Cisco Nexus 9000 C93180YC-FX
Software
  BIOS: version 07.70
  NXOS: version 9.3(9)
  BIOS compile time:  05/09/2020
  NXOS image file is: bootflash:///nxos.9.3.9.bin
  NXOS compile time:  12/15/2021 10:00:00 [12/15/2021 14:00:00]

Hardware
  cisco Nexus 9000 C93180YC-FX Chassis
  Intel(R) Xeon(R) CPU D-1528 @ 1.90GHz
  Memory: 16401428 kB
  Board ID: 0x1234567890ABCDEF

  Serial number: FOC12345678

  Active Supervisor: slot 1
  Device name: N9K-1
  bootflash:    4287040 kB (usable)
  kickstart:    4287040 kB (usable)

  Kernel uptime is 365 day(s), 12 hour(s), 30 minute(s), 15 second(s)

  Last reset
  Reason: Reset Requested by CLI command reload
  System version: 9.3(9)
  Service: 

  plugin
  Core Plugin, Ethernet Plugin

BIOS version and NXOS version show firmware and OS levels. Uptime indicates system stability. Serial number and Board ID are unique identifiers. Last reset reason shows why the switch rebooted.

Show version with module details

show version module 1

Module 1
  Description: 48x10G + 6x40G/100G Ethernet Module
  Model: N9K-X9636C-RX
  Hardware version: 1.0
  Serial number: FED9876543
  Software version: 9.3(9)
  BIOS version: 07.70
  MAC address: 00:1a:2b:3c:4d:5e
  Number of ports: 54
  Status: ok

Shows specific line card details: model, hardware version, serial number, port count, and operational status. Useful for verifying module compatibility and health.

Understanding the Output

The 'show version' output is divided into software and hardware sections. The Software section includes BIOS version, NXOS version, image file location, and compile time. The Hardware section lists chassis model, CPU, total memory, Board ID, serial number, active supervisor slot, device name, and storage sizes. The 'Kernel uptime' line shows how long the switch has been running since last reload, which is critical for diagnosing stability issues. The 'Last reset' section indicates the reason for the last reboot (e.g., reload command, power cycle, crash). Healthy values include uptime consistent with expected operation, no crash-related reset reasons, and memory usage within normal limits. Problematic values include short uptime indicating frequent reboots, 'Reset due to hardware failure' or 'Reset due to watchdog' indicating hardware or software issues, and low memory warnings.

Configuration Scenarios

Pre-Upgrade Verification

Before upgrading NX-OS from version 9.2(4) to 9.3(9), verify current version and hardware compatibility.

Topology

Single Nexus 93180YC-FX switch (standalone)

Steps

1.Connect to the switch via SSH or console.
2.Enter EXEC mode and run 'show version'.
3.Note the current NX-OS version, hardware model, and memory.

Configuration

! No configuration required; command is executed in EXEC mode.
show version

Verify: Confirm that the output shows NXOS version 9.2(4) and hardware model C93180YC-FX. Verify that memory is sufficient for the target version (e.g., 16 GB).

Watch out: Ensure the bootflash has enough free space for the new image; use 'show boot' to check.

Post-Reboot Troubleshooting

A Nexus 9000 switch rebooted unexpectedly. Use 'show version' to determine the cause.

Topology

Single Nexus 93180YC-FX switch

Steps

1.Log into the switch after reboot.
2.Run 'show version' and examine the 'Last reset' section.
3.If reason is 'Reset due to hardware failure', check hardware logs.

Configuration

! No configuration needed.
show version

Verify: Look for 'Last reset Reason: Reset Requested by CLI command reload' (planned) or 'Reset due to software failure' (crash).

Watch out: If the reason is 'Unknown', it may indicate a power loss or hardware issue; check environmental logs.

Troubleshooting with This Command

When troubleshooting system issues on Cisco NX-OS, 'show version' is the starting point. The 'Kernel uptime' field indicates how long the switch has been running; a short uptime suggests recent reboots, which could be due to crashes, power cycles, or administrative reloads. The 'Last reset Reason' is critical: 'Reset Requested by CLI command reload' indicates a planned reboot, while 'Reset due to software failure' or 'Reset due to hardware failure' points to problems. If the reason is 'Reset due to watchdog', it often indicates a software hang. Compare the 'System version' with the expected version; mismatches may occur after incomplete upgrades. The 'Memory' field shows total RAM; if memory usage is high (check with 'show process memory'), it could cause instability. The 'Serial number' and 'Board ID' are useful when opening TAC cases. For modular chassis, use 'show version module <slot>' to check individual line cards; a module showing 'Status: faulty' or missing indicates hardware failure. In virtual PortChannel (vPC) setups, ensure both peers run the same NX-OS version; 'show version' on both switches confirms consistency. If the switch fails to boot, the 'kickstart' image information helps verify the boot process. Always correlate 'show version' output with 'show logging last 50' to see events leading to a reboot.

CCNA Exam Tips

Memorize that 'show version' is the first command to verify OS version and hardware compatibility in any troubleshooting scenario.

For CCNP Data Center, know that 'show version' also displays the kickstart image and boot variable, which are important for understanding the boot process.

Be able to identify the supervisor module and line card models from the output, as these are often tested in design questions.

Common Mistakes

Confusing 'show version' with 'show inventory' – version shows software and hardware summary, inventory shows detailed component serial numbers.

Assuming 'show version' shows running configuration – it does not; use 'show running-config' for that.

Overlooking the 'Last reset reason' field – it is critical for identifying why a switch rebooted unexpectedly.

Platform Notes

On Cisco NX-OS, 'show version' output differs from Cisco IOS in several ways. NX-OS includes a separate 'kickstart' image field, which is used for the boot process, while IOS uses a single image. NX-OS displays 'BIOS version' and 'NXOS image file' distinctly. The 'Hardware' section lists 'Board ID' and 'Memory' in kilobytes. On Nexus 9000 series, the output also includes 'Active Supervisor' slot information. In contrast, IOS 'show version' typically shows 'ROM: System Bootstrap' and 'System image file' without separate kickstart. On Cisco IOS-XR, the equivalent command is 'show version' but output includes 'ROM Monitor' and 'System uptime' differently. For Nexus 3000/3100 platforms, 'show version' output is similar but may lack supervisor details. On older Nexus 5000/6000, the command also shows 'plugin' information. When comparing across platforms, always check the 'NXOS version' field; on IOS, it's 'IOS version'. For troubleshooting, NX-OS 'show version' includes 'Last reset Reason' which is more detailed than IOS's 'System restarted at' line. On Nexus 9000 with Application Centric Infrastructure (ACI), 'show version' displays APIC-related info. Always use 'show version' on each switch in a vPC pair to ensure version consistency.

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