Cisco router info.

[techs]

I need to understand something about Cisco routers. I see used ones advertised with 8/16 where it is explained as Flash/Dram. I am trying to find out if there is a third type of memory called NVRAM in Cisco routers or is that the Flash ram?
thanks

[dddwarp]

I need to understand something about Cisco routers. I see used ones advertised with 8/16 where it is explained as Flash/Dram. I am trying to find out if there is a third type of memory called NVRAM in Cisco routers or is that the Flash ram?
thanks

Flash is basically an erasable reprogrammable ROM that holds the OS. It is retained even when the power is off.

RAM provides caching and holds the routing tables. It is cleared when powered off.

NVRAM is nonvolatile RAM that holds the router's startup config and it also retains when powered off. This is what you "write memory" to to save your config when you make changes.

Cisco did a great thing by seperating Flash which is holds the OS and the NVRAM that holds the config. You make as many changes you want without screwing with the OS

[tommo666]

Plus the flash is often removeable ie in a pcmcia card, which means it's upgradeable. Cisco sell various levels of OS from basic to the 'kitchen sink' versions which contain everything. They all vary is size plus each release seems to get bigger :-) so larger flash is required.

The IOS is stored on the flash as a compressed image which is uncompressed to the system ram, normally simms or dimms.