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New Member

Cisco 3750 Switch

I have a cisco 3750 switch that had the flash formatted. How can I re-install the IOS image on the switch?

New Member

Re: Cisco 3750 Switch


If you have a copy of the IOS.

You need to install a tftp server and download it to flash

switch# copy tftp flash

enter ip address

source name

destination name.

If the ios you have is a .tar file you can download it to flash

switch#archive download-sw flash:

If you don't have an ios, you need to buy a Cisco SMARTnet for your device.


New Member

Re: Cisco 3750 Switch

Hi Jorg,

Thanks a lot. Just to inform you that the prompt on the 3750 device is (switch:). When I type (?) this is what I get;

? -- Present list of available commands

boot -- Load and boot an executable image

cat -- Concatenate (type) file(s)

copy -- Copy a file

delete -- Delete file(s)

dir -- List files in directories

flash_init -- Initialize flash filesystem(s)

format -- Format a filesystem

fsck -- Check filesystem consistency

help -- Present list of available commands

load_helper -- Load and initialize a helper image

memory -- Present memory heap utilization information

mkdir -- Create dir(s)

more -- Concatenate (display) file(s)

rename -- Rename a file

reset -- Reset the system

rmdir -- Delete empty dir(s)

set -- Set or display environment variables

set_bs -- Set attributes on a boot sector filesystem

set_param -- Set system parameters in flash

sleep -- Pause (sleep) for a specified number of seconds

trap -- Cause a software breakpoint to occur

type -- Concatenate (type) file(s)

unset -- Unset one or more environment variables

version -- Display boot loader version


With the switch with that sort of prompt, how do I even take it to the normal privilege prompt (switch#)


New Member

Re: Cisco 3750 Switch


Just did this today due to the same prompt. I used hyperterm for the term emulation. I found the info in the 3750 Switch Software Configuration Guide - Recovering from Corrupted Software By Using the Xmodem Protocol. Very slow but went well.

Step 3 Connect your PC with terminal-emulation software supporting the Xmodem Protocol to the switch console port.

Step 4 Set the line speed on the emulation software to 9600 baud.

Step 5 Unplug the switch power cord.

Step 6 Press the Mode button, and at the same time, reconnect the power cord to the switch.

You can release the Mode button a second or two after the LED above port 1 goes off. Several lines of information about the software appear along with instructions:

The system has been interrupted prior to initializing the flash file system. The following

commands will initialize the flash file system, and finish loading the operating system





Step 7 Initialize the flash file system:

switch: flash_init

Step 8 If you had set the console port speed to anything other than 9600, it has been reset to that particular speed. Change the emulation software line speed to match that of the switch console port.

Step 9 Load any helper files:

switch: load_helper

Step 10 Start the file transfer by using the Xmodem protocol.

switch: copy xmodem: flash:image_filename.bin

Step 11 After the Xmodem request appears, use the appropriate command on the terminal-emulation software to start the transfer and to copy the software image into flash memory.

Step 12 Boot the newly downloaded Cisco IOS image.

switch:boot flash:image_filename.bin

Step 13 Use the archive download-sw privileged EXEC command to download the software image to the switch or to the switch stack.

Step 14 Use the reload privileged EXEC command to restart the switch and to verify that the new software image is operating properly.

Step 15 Delete the flash:image_filename.bin file from the switch.

Super Bronze

Re: Cisco 3750 Switch

If you do need to load flash via a console cable, you might check whether the console port can be configured faster than 9600 and/or whether there's a faster terminal file transfer protocol that's available.

New Member

Re: Cisco 3750 Switch

Loading via xmodem is slow and not 100% reliable. About 1 in 4 loads seem to be bad and I end up having to copy again. Not my favorite activity. The easiest thing to do is set it up and don't even look at it for several hours.

Also, make sure your computer won't go to sleep during the transfer.

New Member

Re: Cisco 3750 Switch

Thanks. I've the doc, tried the steps and got up to step 10. I got an error message during the xmodem transfer, "I/O error". What does that signify? That is the point I've been stuck in since yesterday.

New Member

Re: Cisco 3750 Switch

Make sure that hyperterm is set at 9600. When I tried setting mine at 115000, I received the i/o error msg. Hope that works for you.

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