Upgrading the Cisco Switch IOS

According to business need, you will need to upgrade the OS of your network device in your infrastructure as a Network Administrator/Engineer.

I’d like to share the experience of upgrading the IOS in Cisco to the beginners and for those who haven’t done this yet.

Before complete the task, you should know and prepare the following.

- You must have correct IOS License for your devices
- You must have backup of current running configuration and IOS.
- You must have Local/Remote TFTP Server/FTP/SFTP Server to keep backup files and new IOS.
- You should prepare pre-configured same model device if you have. So you can replace if your task was something wrong.
- Upgrading task should do in Maintenance Windows. You shouldn’t do it however you have very good hands-on experience for that.
- You should read Tech Notes from Cisco about Bugs for your new IOS before upgrade. Then you can expected what need to be done if something unexpected issue occur.
- Be ensure the role and function of your device.

Let’s start the task if you well-prepared above steps.

In this example, I’ll use Cisco Catalyst 3560 PoE Switch to upgrade the IOS as need SSH to enable on it and current IOS do not support SSH because of it is not loaded cryptoimage IOS. Cryptoimage show include crypto and K9 in the file name.

Let’s begin.

- Check the IOS Version of switch. Take a look the photo and take note on red highlighted area for DRAM and Flash Capacity.

   "show version"

- Now, let’s check flash memory space. You would need to delete old IOS if there   is not enough free space to copy new IOS. Take note on red highlighted area. In this example, free space is enough.

 "show flash"

- Login with cisco id and password at Cisco Software Download webpage.

  Find the correct IOS for your switch model. As shown in picture, please download correct IOS as your need. (Ensure to use correct subscribe license feature, DRAM/Flash specification of yours). Take note IOS File Size and MD5 Hash Value too to re-check once it is loaded in Switch.

- Copy downloaded IOS to TFTP/FTP/SFTP Server. In my example, I used TFTP Server.
- Console in to switch and copy IOS from TFTP Server to flash memory of switch.

   "copy tftp flash"

- Once copy task finished, you need to check md5 has value as below to ensure your IOS file didn’t corrupted between processes.

  "verify /md5 flash: put new ios image file name with file extension here"

- If MD5 hash value is correct, will change booth path of switch from old IOS to new IOS as below.

  "boot system flash: put new ios image file name with file extension here"

- After that, copy running configuration to startup configuration as below.

  "copy running-config startup-config" or "write memory" or "write"

- Reload the switch then. Your switch should working as expected without any issue if your upgrading complete successfully.

- In this post, I didn’t mentioned details about IOS Licensing, Clearing Flash Memory space, checking booth path from zip file in Flash and setting up the TFTP Server. I’ll write about those if I’ve got time.

If you are willing to know how to choose correct IOS, please read it here. http://www.ictformyanmar.com/2014/03/what-is-different-ip-base-and-ip.html

However this post demonstrate the task with Switch, you could reference for router and firewall IOS upgrading task too.
But depends on the role of device, steps can be a bit different and complex because of you will need some requirement and pre-arrangement.

I’ll write more details about router and firewall if I’ve got a chance.

Have a good time.

(Be knowledgeable, pass it on then)

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