Cisco IOS is the operating system used in most Cisco enterprise-class products. Some Cisco products host a USB port that can be used to upgrade the IOS without the use of a TFTP connection. The USB drive you want to use needs to be formatted using the FAT file system and must have enough space to host the IOS file and the backup you are making of your current IOS.
Download the last IOS image designed for your equipment from your Cisco account.
Insert the USB drive into your computer and copy the file from your computer to the root of the USB drive.
Insert the USB drive into your equipment, connect your laptop to the admin port of your equipment and enter your login and password.
Type “copy flash usbflash1:Name-of-your-backup-IOS” to make a backup copy of your current IOS.
Type “copy usbflash1:name-of-the-new-IOS flash” to upgrade to the last IOS.
Type “yes” when asked if you want to overwrite the current IOS.
Type “reload” to switch from the old IOS to the new one.
Make sure to download the right IOS for your equipment. Loading the wrong IOS can disable your equipment. Make sure your equipment has enough RAM for the new IOS.
Never upgrade to a new IOS on production equipment during business hours, as the upgrade can sometimes fail. Either test it on identical backup equipment or do the upgrade outside of business hours.