Upgrading Cisco IOS Images: Best Practices

Jose Chapa • March 28 2023

Upgrading the operating system of networking devices in an enterprise environment is a critical task that requires careful planning and execution. IOS is the operating system that powers Cisco networking devices, including routers and switches. Upgrading the IOS can provide several benefits such as enhanced security, improved performance, and support for new features. In this article, we will discuss how to upgrade the IOS versions of networking devices at an enterprise location in a Cisco environment.

Pre-Upgrade Preparation:

Before upgrading the IOS of a networking device, it is essential to take some preparatory steps to ensure a smooth and successful upgrade. These steps include:

1. Change approval: In a large enterprise environment, change approval and change tracking are very important. After evaluating the change scope and the change risk, make sure you document the change and follow your environment's change procedures.

2. Backing up the current IOS image and configuration file: Before upgrading, take a backup of the current IOS image and configuration file. This backup will be used to restore the device if the upgrade fails or if there is an issue after the upgrade. You will want to compare the startup and running configuration and decide which one to proceed with.

3. Check compatibility: Ensure that the new IOS version is compatible with the hardware and other devices in the network. Also ensure the ROMMON of the device is compatible, otherwise it will need to be upgraded first.

4. Check available space: Ensure that the device has enough space to store the new IOS image. IOS images can be large, so it is crucial to check if the device has sufficient space to accommodate the new image. To clear space you should remove any older unused IOS images on the device.

5. Check for any known issues: Check Cisco's website for any known issues with the IOS version you are planning to upgrade to. It is also essential to review the release notes to understand any new features or changes.

Upgrade Process:

Once the preparatory steps are complete, you can proceed with the IOS upgrade process. The upgrade process includes the following steps:

1. Download the new IOS image: Download the new IOS image from Cisco's website and save it to your computer. You can then upload to the designated file transfer server if applicable.

2. Log into the device: Using your preferred terminal, log into the device. Make sure you have proper authorization to make the changes. It would be best to log in with a serial connection while on premises, or via a remote terminal with cellular backup service.

3. Transfer the new IOS image: You can either use a dedicated file transfer server or use your computer as a file transfer server, depending on your environment. There are many protocols to choose from. You could use SCP, which is a modern protocol that is both secure and fast. If your file transfer server or cisco device don't support SCP, then you may use SFTP instead.

4. Install the new IOS image: Install the new IOS image on the device. After changing the boot file to the new IOS image, it will be ready to perform the upgrade.

5. Reload the device: The change will not take effect until it reloads. This means the device must be offline briefly while the change takes effect. Make sure you perform the reload during a time in which it will have the least business impact, and make sure any affected parties are aware of the change window.

Post-Upgrade Verification:

After the IOS upgrade is complete, it is crucial to verify that the device is functioning correctly. The verification process includes the following steps:

1. Verify the IOS version: Verify that the device is running the new IOS version.

2. Verify the device configuration: Check the device configuration to ensure that it is the same as the configuration before the upgrade.

3. Test connectivity: Test connectivity between the device and other devices in the network to ensure that everything is working correctly.

4. Monitor the device: Monitor the device for any issues or errors after the upgrade. This can be done using various network monitoring tools.

In conclusion, upgrading the IOS versions of networking devices at an enterprise location in a Cisco environment requires careful planning and execution. Following the steps outlined above can help ensure a smooth and successful upgrade process. Remember to take backups, check compatibility and available space, and verify the IOS version and device configuration after the upgrade. With proper planning and execution, upgrading the IOS can provide significant benefits to your network.