Upgrade Cisco IOS in a Router or a Switch

upgrading IOS on Cisco routers and switches is hightly 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.

Follow this procedure if you want to upgrade cisco IOS

NOTE :- Before doing any upgrades plesae take a complete backup of your cisco device configuration for safer side

Download the Correct version of Cisco IOS for you from here http://www.cisco.com/tacpage/sw-center/index.shtml

Write Unsaved configurations

ciscorouter# write memory
Building configuration…
[OK]

Check space on Flash Memory

ciscorouter# show flash

Make sure you have the space left on your cisco device.

Backup Startup Configuration

Setup a TFTP server in the same IP range as the Cisco device to backup the configs, IOS image and also for later to upload the new IOS image.

testrouter# copy startup-config tftp
Address or name of remote host []? 10.10.10.2
Destination filename [startup-config]?
!!
1278 bytes c opied in 0.100 secs

Backup Current IOS Image

testrouter# copy flash: tftp:
Source filename []? xxxxx-xx-xx.121-x.XB
Address or name of remote host []? 10.10.10.2
Destination filename [xxxxx-xx-xx.121-x.XB]?

Now, Load the new IOS image from the TFTP onto the flash

ciscorouter#copy tftp: flash:
Address or name of remote host []? 10.10.10.2
Source filename []? c3560-ipbasek9-mz.122-40.SE.bin
Destination filename [c3560-ipbasek9-mz.122-40.SE.bin]?
Accessing tftp://10.10.10.2/c3560-ipbasek9-mz.122-40.SE.bin…
Loading c3560-ipbasek9-mz.122-40.SE.bin from 10.10.10.2 (via Vlan1): !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!
[OK - 8295106 bytes]

8295106 bytes copied in 124.571 secs (66589 bytes/sec)

Now you need to make sure you are booting with the correct version of IOS image for this you need to use the following command to set.

testrouter(config)#boot system flash:/c3560-ipbasek9-mz.122-40.SE.bin

Now you need to reload the Cisco Router

testrouter# reload

After rebooting cisco device with the new Cisco IOS image you need to make sure this use the following command

testrouter# sh ver

That’s it now we are using the latest IOS on your cisco device