How to Install or Upgrade Cisco IOS on Switch or Router using TFTP Server

Install or Upgrade IOS using TFTP server

To install or upgrade an IOS Operating System (Internetwork Operating System) on switch or router using TFTP server, we must make sure of following things mentioned in this tutorial.

IOS (Internetwork Operating System) is stored in the flash memory of Cisco router. Tough, flash is non volatile memory (permanent memory), we may have to install fresh Internetwork Operating System (IOS) or upgrade IOS. Fresh installation may be needed when there is a router malfunctions or due to security threats or corruption of Internetwork Operating Systems.

Trivial File Transfer Protocol (TFTP) helps to install, upgrade and backup Internetwork Operating System. TFTP server has to be installed and configured on a system.

TFTP makes use of Port 69 and User Datagram Protocol to perform all its communication operations. It is widely used in Local Area Networks but not over the internet. TFTP is not mostly used over the internet because TFTP does not provide authentication. Due to the security reasons we will not use TFTP server over the internet.

Trivial File Transfer Protocol is also not that reliable as it uses User datagram Protocol.

To install an Operating System (Internetwork Operating System), we must make sure of following things

  1. Trivial File Transfer protocol must be in the network
  2. Connectivity must be available among the systems
  3. Download IOS.
  4. Copy downloaded IOS into root folder of TFTP Server
  5. Erase IOS present on the router

We can download the required version of Internetwork Operating System from Cisco website. Once downloaded, add the file to the Trivial File transfer Protocol Server. To erase present Internetworking Operating System in the router or a switch, use the command as shown below

CISCO_ROUTER# erase flash

As Internetwork Operating System (IOS) is present in Flash memory, on erasing Flash, all the files including IOS are erased. The command must be executed from Privileged EXEC mode.

After execution of the above command, the IOS from the router is removed. Now we have to install a new or fresh IOS on the router. To install fresh IOS from TFTP server, use the following command

CISCO_ROUTER# copy tftp flash

After the IOS is copied, for the router to use new IOS, we must reload the router. To reload the router, use any one of the following steps

  1. Power off the router and power it on.
  2. Use ‘reload’ command in privileged EXEC mode.

To avoid new security threats Cisco often upgrades Internetwork Operating System regularly. To install or upgraded IOS on router, use following command

CISO_ROUTER# copy tftp: flash

Before using the above command download and copy the updated IOS image file from the Cisco website and also make sure if the router has sufficient memory to store the upgraded files in the memory

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