How to Upgrade IOS on Cisco Routers
Upgrading IOS on Cisco routers and network switches is highly recommendable because of the following reasons
Patch critical vulnerabilities: Just like any other network device or application, Cisco routers and switches are also prone to security holes. And because routers and switches are critical to network infrastructure, you should plug these security holes as soon as possible.
Incorporate new features: Unless an update is simply a bug fix, every new release of the Cisco IOS includes new features. Upgrading your routers and switches in a timely manner means you’ll have more features to potentially make your job easier.
Stay current: “Staying current” with the latest IOS may sound like a flimsy justification to upgrade, especially when you consider your daily task list. However, when you consider the many different tools that communicate with the router’s IOS, staying current can take on a new importance. For example, if you’re using a SNMP network management tool, it may require your router to run a certain version of the IOS.
Things You'll Need
Microsoft Windows 7 computer with telnet client and TFTP service installed
IP address of the Microsoft Windows 7 computer
Cisco router with telnet service enabled
IP address of the Cisco router
Cisco IOS image located in the TFTP service root directory
Password for the Cisco router telnet connection
Privilege Exec mode password for the Cisco router
Steps to upgrade IOS on Cisco router
1. Click the "Globe" button, then select the "Search" box, and then type "cmd." Right-click on the command line icon that appears and click "Run as Administrator." The command line window will appear.
2. Enter "telnet x.x.x.x," on the command prompt, replacing the "x.x.x.x" with the IP address of a Cisco router, and then press the "Enter" key. Telnet will then connect to the Cisco router.
3. Enter the telnet password when requested on the command prompt, and then tap the "Enter" key.
4. Enter "enable" on the command prompt, and tap the "Enter" key. Type the Privilege Exec password for the Cisco router when requested, and press the "Enter" key.
5. Enter the "copy tftp flash" command on the command prompt, and then tap the "Enter" key.
6. Enter the IP address of the Windows 7 computer on the command line as the IP address of the TFTP server from which to copy the new IOS image, and then tap the "Enter" key.
7. Enter the exact name of the IOS file on the command prompt when requested, and then tap the "Enter" key.
8. Enter the name of the IOS file as the destination file name and tap the "Enter" key.
9. Type "Y" when the "Erase flash: before copying? [confirm]" message appears, and press the "Enter" key. The new IOS file will then be copied to the router flash drive.
10. Enter "configure terminal" on the command line, and then tap the "Enter" key.
11. Type "no boot system" and press the "Enter" key. Then type "boot system flash:ios_filename," except replace the "ios_filename" with the exact name of the IOS file that was just transferred to the Cisco router, and then tap the "Enter" key.
12. Type the "exit" command at the command prompt and tap the "Enter" key, and then type "write memory" and tap the "Enter" key.
13. Enter the "reload" command on the command prompt, and then press the "Enter" key. The Cisco router will restart and boot into the new IOS.