How to default a Cisco 9300 switch and load a new configuration (Step-by-Step Guide)

Whether you are deploying a new switch, repurposing an existing device, or troubleshooting network issues, resetting a Cisco Catalyst 9300 switch and loading a new configuration is a fundamental skill for network professionals.

Step 1: Connect to the Switch Console

• Use an RJ-45 or USB mini-B console cable to connect your PC to the switch.
• Open terminal software (PuTTY, SecureCRT, MobaXTerm).
• Configure serial settings: 9600 baud, 8 data bits, no parity, 1 stop bit, no flow control.

Tip: If using the USB console port, check your PC's Device Manager to find the correct COM port number.

Step 2: How to Factory Reset Cisco Switch Using CLI (Recommended)

This is the fastest method when you have administrative access to the switch.

1. Enter privileged EXEC mode:

Switch> enable

2. Erase the startup configuration:

Switch# write erase

Confirm by pressing Enter when prompted.

3. Reload the switch:

Switch# reload

When asked to save the configuration, type no and press Enter. The switch will now reboot into a factory default state.

Step 3: Reset Cisco Catalyst 9300 Switch via ROMMON for Password Recovery

Use this method only if you are locked out of the switch.

1. Power cycle the switch. As it boots, repeatedly press the Mode button on the front panel until the switch: prompt appears.
2. At the prompt, enter these commands to boot while ignoring the current configuration:

switch: SWITCH_IGNORE_STARTUP_CFG=1
switch: boot

3. Once the switch has booted, enter privileged mode (no password is required):

Switch> enable

4. Permanently erase the old configuration and restore the normal boot process:

Switch# write erase
Switch# configure terminal
Switch(config)# no system ignore startupconfig switch all
Switch(config)# end
Switch# reload

Step 4: Steps to Load New Configuration

• From USB:

Switch# copy usbflash0:new-config.txt running-config

• From TFTP:

Switch# copy tftp:///new-config.txt running-config

Step 5: Save the Configuration

A newly loaded configuration must be saved to become permanent.

1. Verify the new running configuration:

Switch# show running-config

2. Save the configuration to memory:

Switch# copy running-config startup-config

or the shortcut:

Switch# write memory

Key Considerations

• Backup First: Always back up your current configuration to an external location before performing a reset.
• Smart Licensing: After a factory reset of a Cisco switch, the device will enter Smart Licensing evaluation mode. Make sure to register and activate your licenses according to Cisco's policy to maintain compliance.

Frequently Asked Questions

Q1: How do I clear running configuration on Cisco switch?

A: The running configuration cannot be cleared directly without reboot. To clear it, erase the startup configuration using write erase and reload the switch. This causes the switch to boot clean, without loading the previous configuration into memory.

Q2: How do I save running config to startup on a Cisco switch?

A: Use copy running-config startup-config or write memory to save the active running configuration permanently so it loads after reboot.