Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
In Cisco parlance, it's the "brains" of a chassis type switch. Other vendors may call it by another name.
Cisco chassis that take supervisor engine often take different variants (often new variants over time). For example, in the 4500 series you have (somewhat recently) sup-6, sup-7 and sup-8, and in the 6500 series, sup720 and sup2T. In the forgoing, there's some variants of particular sups, for example, the sup7L-E vs. sup7-E, or the sup720B vs. VS-S720 (and the XL variants of the last two).
The principle advantage, and why such was introduced, you can swap "brains" like you can swap other module cards; often using all or most other chassis components. The disadvantage of this approach, it's more expensive, uses more space, and advances in technology might be held back by other components. I.e. it's difficult to make major advances in a chassis, unless many or all other components are upgraded, especially if you're trying to maintain support for older components.
