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Difference between IOS, Firmware and bootldr on a Cisco switch?

What is the difference between IOS, Firmware and BOOTLDR?

How do you upgrade each one?

Are they three words for the same thing?

How come some switches have a bootldr statement and others don't even though they can be identical switches with very similar versions of IOS?

Is firmware and IOS the same thing?

switch 1 and 2 are identical 6500 switches but switch1 has a bootldr but switch 2 does not have a bootldr?

switch2#sh ver
Cisco IOS Software, s72033_rp Software (s72033_rp-ADVENTERPRISEK9_WAN-M), Version 12.2(33)SXI3, RELEASE SOFTWARE (fc2)
ROM: System Bootstrap, Version 12.2(17r)SX5, RELEASE SOFTWARE (fc1)
System image file is "sup-bootdisk:s72033-adventerprisek9_wan-mz.122-33.SXI3.bin"

switch1#sh ver
Cisco Internetwork Operating System Software
IOS (tm) s72033_rp Software (s72033_rp-ADVENTERPRISEK9_WAN-M), Version 12.2(18)SXF16, RELEASE SOFTWARE (fc2)
Image text-base: 0x40101040, data-base: 0x42DDD190
ROM: System Bootstrap, Version 12.2(17r)SX5, RELEASE SOFTWARE (fc1)
BOOTLDR: s72033_rp Software (s72033_rp-ADVENTERPRISEK9_WAN-M), Version 12.2(18)SXF16, RELEASE SOFTWARE (fc2)
System image file is "sup-bootdisk:s72033-adventerprisek9_wan-mz.122-18.SXF16.bin"

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5 Solutions
HellmarkLinux Systems AdministratorCommented:
IOS is the name of the software, it is often part of a single firmware image. For upgrading that, it is as simple as copying the file over to the flash. For a switch, you'll have to copy it over from a TFTP server. Follow this link for a Cisco guide. Routers, which often have compact flash cards, are much easier, since you just  copy over to the CF.

Also, pay little attention to the versions. Cisco is nuts, and you can have one version that is like 12.4(15)T7 that is actually older, with fewer features than something like 12.4(11)XW9. I run into problems with this quite often at work, where we use IOS with Call Manager Express, and we have to be very careful to have the right version in order to have it support the phones needed.
Firmware is the ROM:Bootstrap version. More akin to the BIOS on a PC pre-boot.
IOS is the operating system
Some CAT OS switches have a mini-OS boot loader. The 6500 was CAT OS to start, so depending on the IOS currently running, it may show as BOOTLDR and/or system software. As to the difference between the two switches, there could be hardware difference as well as the obvious IOS image versions with 12.2(33) being much newer than 12.2(18)
Dragon0x40Author Commented:
Hellmark and lrmoore seem to disagree on what firmware is.

Hellmark - IOS is the name of the software, it is often part of a single firmware image. (Firmware is updatable)
lrmoore - Firmware is the ROM:Bootstrap version (Firmware is not updatable)

I have worked on Foundry switches before and they do have a seperate image file for firmware and IOS but I have only updgraded the IOS for Cisco. When soemone starts talking about upgrading the firmware for Cisco then I don't know what they are referring to or how to perform that kind of upgrade.
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HellmarkLinux Systems AdministratorCommented:
lrmoore hasn't said anything to suggest that it is not updatable. They expanded on what I said. I said that IOS was the name of the software, and lrmoore specified that it was the name of the OS. I had said that IOS is often part of one single file for firmware (which in the systems I've worked on, it has been the case), and lrmoore gave more specific information related to when it would and wouldn't be.

The differences in your situation, in my experience, seem to be more related to IOS differences, and that is the .bin file referenced in your quoted text.
I think we actually agree. And sometimes the bootstrap version is upgradeable. Sometimes it is a physical ROM chip swap out.
In some switches, the "firmware" is the OS. For example Cisco Small Business (aka Linksys) switches show firmware version and upgrade firmware features in the web gui and that's all.
Most true Cisco switches do have an underlying firmware that boots the system, then finds the OS to load. That's why you can boot it with no OS, then upload a new one, or boot outside the OS to recover the password, etc.
Dragon0x40Author Commented:
I am still not clear on all the terms. Please provide feedback.

ROM/bootstrap: boots the cisco device even if no IOS is available. If IOS available it attempts to boot the IOS. May or may not be upgradable.

Bootldr: Transitional software used to transition from bootstrap mode to loading IOS. More common on older devices as a seperate file but on new devices is combined with the IOS.

IOS: Cisco device operating system. stored in various locations on different platforms.

Firmware: I don't have any idea!

Dragon0x40Author Commented:
If someone says to me to upgrade the firmware then I don't know what they are telling me to do?

I have only upgraded IOS on Cisco native IOS devices so that is why I am probably confused.

Anybody that can explain it a different way?

I remember that on a IBM PC it was possible to flash the bios and update it. (ROM/bootstrap/firmware?)
Load DOS (bootloader/firmware?)
Execute windows (IOS)

Now Windows doesn't need to load DOS just like Cisco IOS does not need a bootldr?

IEEE DefinitionInstitute of Electrical and Electronics Engineers (IEEE) Standard Glossary of Software Engineering Terminology, Std 610.12-1990, defines firmware as follows:

"The combination of a hardware device and computer instructions and data that reside as read-only software on that device.
Notes: (1) This term is sometimes used to refer only to the hardware device or only to the computer instructions or data, but these meanings are deprecated. (2) The confusion surrounding this term has led some to suggest that it be avoided altogether."
Dragon0x40Author Commented:
Then my switch has the following?

1#upgrade ?
  epld         Electrically programmable logic devices
  firmware     Upgrade firmware image
  hw-module    Slot/subslot level commands
  rom-monitor  ROM Monitor

upgrade firmware? what does that do?
All I can tell you is that Cisco refers to IOS as "software image"
Generally speaking, "firmware" and IOS may be used interchangably. If someone says "upgrade the firmware" then one could assume that they mean the IOS, but always confirm.
In your case with the upgrade command, honestly I've never seen it, nor can I find "upgrade firmware" in the master list of IOS commands.
I'm assuming that this is output from one of your cat6500's ?
If you look at the upgrade guides for 6500's, you will see a distinct difference between "firmware" and software, where firmware is clearly *not* IOS.
Just search for firmware on this page:

Very old pre-ios switches did refer to the OS as firmware

Some modules have upgradeable firmware, i.e. modem modules

Dragon0x40Author Commented:
I searched for firmware but I only get the following line:

Firmware compiled 27-Jan-06 16:09 by integ Build [100]

How can I determine the difference between firmware and software? I must be missing something?
HellmarkLinux Systems AdministratorCommented:
As said, firmware for cisco typically is referring to the bin file that contains IOS. The bootloader is just something that starts when the system powers up, and brings that bin file into memory, so IOS can run. Sometimes that can be upgraded, sometimes it doesn't. Most of the time, even if it can be upgraded, there really isn't much point, unless a newer version of IOS requires boot loader upgrade (which I can't even remember when that has happened last).
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