How to Upgrade Cisco IOS

Before upgrading IOS, you need to obtain the latest IOS version. This is usually done by logging in at and selecting your device type and version. The downloaded file must then be transferred to a flash drive of the device, usually via TFTP or FTP.

Let’s upgrade Cisco Catalyst 2960 to a newer version of IOS via TFTP. Here are the steps:

1. We need to place the image file to a TFTP server that is reachable by the switch:

TFTP server IOS

2. Next, we need to transfer the file from the TFTP server to the flash memory of the switch. This can be done by issuing the copy command on the switch:


SW1#copy tftp flash
Address or name of remote host []?
Source filename []? c2960-lanbasek9-mz.150-2.SE4.bin
Destination filename [c2960-lanbasek9-mz.150-2.SE4.bin]? 

Accessing tftp://
Loading c2960-lanbasek9-mz.150-2.SE4.bin from !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[OK - 4670455 bytes]

4670455 bytes copied in 3.079 secs (121951 bytes/sec)

Notice how we need to enter the IP address and the exact filename of the image we wanted to copy. We’ve also specified that the destination filename will be the same as the source filename.

By issuing the show flash: command, we can see that the file was copied to the switch:

SW1#show flash:
Directory of flash:/

    1  -rw-     4414921            c2960-lanbase-mz.122-25.FX.bin
    3  -rw-     4670455            c2960-lanbasek9-mz.150-2.SE4.bin
    2  -rw-        1052            config.text

64016384 bytes total (54929956 bytes free)

3. The last step is to configure the switch to load the new IOS version. If we reboot the system now, the old IOS file will be loaded:

Proceed with reload? [confirm]
C2960 Boot Loader (C2960-HBOOT-M) Version 12.2(25r)FX, RELEASE SOFTWARE (fc4)
Cisco WS-C2960-24TT (RC32300) processor (revision C0) with 21039K bytes of memory.
2960-24TT starting...
Base ethernet MAC Address: 000C.8536.AA3B

We need to instruct the switch to load the new file. The easiest way to do it is by using the boot system command. This command accepts a single parameter – the name of the file to load:

SW1(config)#boot system c2960-lanbasek9-mz.150-2.SE4.bin

4. The last step is to save the configuration and reload the device. We can verify that the newer version of IOS is being used by issuing the show version command:

SW1#show version
Cisco IOS Software, C2960 Software (C2960-LANBASEK9-M), Version 15.0(2)SE4, RELEASE SOFTWARE (fc1)
Technical Support:
Copyright (c) 1986-2013 by Cisco Systems, Inc.
Compiled Wed 26-Jun-13 02:49 by mnguyen

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