I don't remember all of the details, but the traditional IOS is one file, that the device loads/decompresses/boots, loading the whole thing into memory (which is quite large when you are talking about a 6500). The installed version is an extracted version into the flash memory system, and it boots in a new manner.
This new method uses a micro-kernel, that runs under the whole system, and then loads up other modules as needed, sort of like a Virtual Machine, where it then loads up sub-systems based on the needs of the device, where it can also enforce the proper running of the sub-systems. The traditional IOS loads up all modules into one memory space, and relies on the other components doing what they are supposed to do.
Due to the micro-kernel based setup, one component of the IOS crashing doesn't cause the whole switch to crash, it can restart just a portion of the system.
Lower memory usage (at least initially, since it doesn't load the line code for cards not in the system, so that if you don't have a WiSM, the WiSM code stays on the flash and out of RAM).
It is possible to patch the system (incremental small updates to fix problems) with minimal installation/down time, instead of full upgrades each time.
Higher processor utilization (the micro-kernel adds overhead), which is a problem if you have a high load on your current system (I believe as of when I last heard it caused up to a 20% increase in processor usage).
Less tested than the traditional IOS method.
As of when I last heard about it (at the Cisco Live! conference last year) not all line cards were supported that are supported in the traditional IOS.
Full upgrades/new installs are a little bit more complex (a few extra steps).
AFAIK, the new method will be the future/default for later generations of Supervisors (which will take into account the additional processor overhead needed). I've been running it on my core at work, and it seems to work well, at least for our purposes.
I'm sure I've missed some things, but this is what I remember of the differences.
Hi everyone, I would like to thank you in advance for any help you can provide a newcomer like myself!
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