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CISCO FIRMWARE & IOS

Posted on 2010-08-19
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Last Modified: 2012-05-10
Hi,

I'm very confused regarding the difference  between CISCO IOS and the Firmware.

Or Is the Cisco IOS and Firmware the same?

Can anyone help me understand this basic concept.

Thanks ,

Nirmal
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Question by:nirmal_s19
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by:qbakies
ID: 33475676
IOS is the actual operating system that you use to program the router or switch through CLI or GUI.  I'm not sure but perhaps you are referring to the image file as 'firmware'?  If so the image file is what tells the router/switch what version of IOS and what features are available to the device.
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by:anoopkmr
ID: 33475704
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by:qbakies
ID: 33475705
Also, PIX/ASA don't use 'IOS', rather they us PIX or ASA software (which is essentially the same thing just not called IOS).
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by:Paresh Patel
ID: 33476305
They are both same and refer to an operating system on Cisco routers and switches.  If someone asks you "which IOS are you running on router/switch?"  it means the same as "which firmware are you running on router/switch?"
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by:szfeco
ID: 33483075
Cisco IOS is the complete operating system. It does a lot of things.
Firmware is a piece of code for a hardware part of the router or other device, not a complete OS.
Usually it does only the functions of the hardware  it is for.

Each interface card has its own lets call as "driver" built in as a firmware. It is on the ROM of the interface card.
If this has a bug, you can upgrade it by uploading it to the flash of the router, and every time the router boots the interface card will use this instead of the stored code in its ROM. Or when the interface card supports it can overwrite the old code with the new one.
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Zxeses earned 500 total points
ID: 33490423
Think of Firmware as Read-Only-Memory (ROM).  Firmware is never stored in flash, otherwise it wouldn't be "firm"-ware. Bios is used as the storage medium for the firmware to store basic bootup information.

Cisco devices come with a ROM based IOS which is a basic OS which boots up should the Bios settings be unable to locate a storage based IOS image.

For example, my Cisco 4510R has this ROM based IOS image:
      ROM: 12.2(44r)SG5

So then on my "flash memory" which is the storage medium on most Cisco devices, is where my current IOS image is stored, this is a full IOS image that includes all the device drivers needed to to bring up whatever feature set I paid for and needed.  "Show Ver" shows you the currently booted image information:

Cisco IOS Software, Catalyst 4500 L3 Switch Software (cat4500e-ENTSERVICESK9-M), Version 12.2(53)SG2, RELEASE SOFTWARE (fc1)

So the boot-up sequence (simplified) is something like this:

ROM -> read bios
ROM -> try to load IOS image specified by bios -> disk:imagename
ROM -> fail -> load ROM IOS "up" image
ROM -> success -> Uncompress and boot the image.
IOS -> Poll the Firmware and bios of all the devices
     Examples:  T1/E1 WIC cards,  T3+ cards, GBIC interfaces, SFP Interfaces
IOS -> Run the appropriate drivers
Drivers -> Offer services available to the IOS
IOS -> configure logic and bring up valid interfaces

I left out a lot there, but you get the idea now.
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by:szfeco
ID: 33490561
boot sequence is correct but:
you can load a firmware only for an interface card  onto the flash, than it will use that one instead of the built-in one.

Let's modify the sequence:

Poll the Firmware - if there is no newer firmware for an interface card use the embedded one, otherwise boot with the new firmware.

We use newer firmware for ATM cards usually to support new features or DSLAM from different vendors.
This case the flash has the IOS (c850-advsecurityk9-mz.124-15.bin) and a firmware file for the if-card (adsl_alc_firmware.bin)

In this case you can store the firmware on the flash.
Every time the router boots, the firmware will load from the flash.
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by:nirmal_s19
ID: 33490809
Hi ZXESES / SZFECO,

Please confirm whether my below understading is correct?

1)The Firmware is generally embedded in the Device Modules and Cisco IOSbundle comes with the    Firmware for the all the hardware installed on the Cisco device.

2) Then what is the Boot strap ?

3) So if I have a switch and now I want to add a new Interface to the switch , so do i have to upgrade the Firmware alone for that switch or do I have to upgrade my IOS ?



 
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by:szfeco
ID: 33491134
1) yes and no :) depends what architecture you have. there are hundreds of pages explaining the possibilities and accomplishments.
Basically when you process something on the CPU of the router, than it sends the data to the interface, where the interface card processing further formatting the data and placing onto the wire with its own specific hardware , which is runing its own firmware.
More low-level tasks can be done by the hardware itself, higher the performance.
If you have a cheap hardware more tasks should be done by the CPU.
IOS is runing on the CPU (not specific CPU), firmware runs on the CPU of the hardware which is designed to do something specific (it can do that task really fast)
if you want to upgrade the firmware, you can even replace the hardware or the ROM contains the code, (not simple) or design the hardware to be able to load the code from an external source (from flash) or even erase the old and store the new code on its ROM.

2) Bootstrap is a process which proceeds without external help. this process starts the router, loads code into the memory to be executed, starts the booting process

3) for the switch no, it should work, only thing to precheck that the interface will be supported by your switch


 

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by:nirmal_s19
ID: 33749994
EXCELLENT SOLUTION
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