Restore Cisco IOS to Cisco Device

1.    Login to the system device.
2.    Once you are in the Cisco device, you can perform the following to load the new Cisco IOS:
    a.    #copy tftp flash
    b.    Address or name of remote host []? The host name or IP you wish to pull from.
    c.    Source filename []? The name of the file you are uploading.
    d.    Destination filename []? Name you want it to show up as in the flash.
    e.    Erase flash: before copying []? You might or might not have this option. This is mostly for old systems and you do not have enough space to hold both the previous and the new IOS.
    f.    If you select erase, it will start erasing the system and upload up the new IOS.
    g.    Use the #show flash command to ensure your new IOS is there.
    h.    #reload
3.    Verify your new IOS version is now loaded through the #show version command upon reload.

Mess With ROMMON Cisco Device

•    While in ROMMON you have three important commands:
    o    >confreg
            You can use this to actually change the boot register config of the device.
    o    >set
            The set command will allow you to actually assign IP addresses to your interfaces.
    o    >tftpdnld
            This will allow you to download your IOS with this command.
    o    >xmodem
            This is horrible, you can use this to upload your IOS through the console port. Good luck with this, but maybe you might have to do this.

Quick Cheat Sheet for How a Cisco Device Boots

1.    Checks the configuration register
    a.    2100: ROMMON
    b.    2101: RXBOOT
    c.    2102: Boot Normally
    d.    2142: Ignore NVRAM
2.    Check for “BOOT SYSTEM” commands in the startup config.
3.    Looks for the first IOS image in flash.
4.    Broadcast for a TFTP server

Upgrading the Firmware and IOS for Cisco 4500X

1.    First verify your firmware and your IOS are loaded into the bootflash by executing the following:
    a.    #dir
2.    Once you verified you have the proper files (if you do not, download the correct ones and follow my “Uploading IOS” guide), enter the following commands in order to keep the system from booting into the old IOS. We will do this to force it into the new firmware and IOS files:
    a.    #configure terminal
    b.    #no boot system flash bootflash:YourCurrentLoadedIOS
    c.    #exit
    d.    #write
3.    Next we are actually going to set the config-register and set the device up to load and boot from the files we uploaded into our flash.
    a.    #configure terminal
    b.    #boot system flash bootflash:YourFirmwareUpgradeFileName
    c.    #boot system flash bootflash:YourCiscoIOSFileName
    d.    #config-register 0x2102
    e.    #exit
    f.    #write
4.    Now you need to verify your boot parameters are correct and the system will boot up into your files you want to load:
    a.    #show bootvar
    b.    Look to make sure your BOOT variable is equal to your boot software you wish to boot. ENSURE you check this because I have had where it would load the files out of order, or not put one in. Just verify.
5.    Next you just need to reload the Cisco device and it should start performing the upgrade. It will take up to 5-20 minutes.
    a.    #reload
    b.    Proceed with reload? Confirm
    c.    Not to self and others, sometimes these switches will get stuck and might need to be power cycled. Have a console cable ready just in case troubleshooting is required to get it to boot back up.
6.    Once the switch has loaded up, verify your software has been upgraded with:
    a.    #show version
7.    Next, you need to reset your boot parameters to only load the new IOS and not the firmware file and change back the config-register for proper boot functionality and order:
    a.    #configure terminal
    b.    #no boot system flash bootflash:YourFirmwareFile
    c.    #config-register 0x0102
    d.    #exit
    e.    #write
8.    Finally, you can clean up the files on the system by using the delete command to delete the firmware file. If you have the space and even though you backed up your IOS (you did backup your IOS right?.....), you might still want to keep the old IOS on there just in case you have issues.
    a.    #delete bootflash:YourFirmwareFileName
    b.    Delete filename? Confirm
9.    You have now completed the firmware and IOS upgrade for your system.

Reference:
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/release/note/OL_24829.html#96288

Uploading IOS to Cisco 4500 Device

1.    First, download the appropriate software for your Cisco device.
2.    Once you have the file downloaded, then copy the IOS to the correct folder where your TFTP will pull from.
3.    Now you are ready to upload the file to the bootflash (this is similar to other Cisco devices, but 4500Xs store it in the bootflash).
4.    Next, perform the following commands to perform the upload:
    a.    #copy tftp: bootflash:
    b.    Address or name of remote host? Input_Your_TFTP_IP
    c.    Destination filename? YouCanChangeOrLeaveDefault
    d.    Now you await for the upload to finish.
5.    After your upload has finished, you can now verify the upload has been completed and your file is showing:
    a.    #dir
   
Reference:
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/release/note/OL_24829.html#96288

Backup Cisco IOS on 4500X

1.    First, log into the Cisco device you wish to upgrade.
2.    Perform the following command to verify which IOS version you are currently running:
    a.    #show version
    b.    Scroll up and look for system image file, will say something like “bootflash:cat4500….” or something like this talking about the booting on flash.
3.    Depending on the version or type of switch, you can do either of the following commands to check the directory to verify how much space and what images are loaded on the Cisco system.
    a.    #dir
    b.    #dir flash:/
4.    So once you find the version IOS you are running, and the name of the config file in the directory, you can copy the original IOS to your TFTP server/client by typing in the following, (again, this is to back up the currently running IOS in case any issues arise with the new IOS. If there are any issues, you can easily re-upload this file back into the Cisco system and recover).
    a.    #copy flash tftp
    b.    #Source filename[]?YourCurrentRunningIOS
    c.    #Address or name of remote host[]?YourIPAddressOfSystemToSendIOS
    d.    Then just wait for the copy to transfer to the backup destination.
    e.    You can check the file location you have your TFTP set to download to in order to verify the IOS has been downloaded.

Reference:
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/release/note/OL_24829.html#96288