From: Jay Hennigan (jay@xxxxxxxx)
Date: Tue Apr 02 2002 - 05:12:16 GMT-3
On Tue, 2 Apr 2002, [gb2312] Eric Wee wrote:
> one shows 14336K/2048K,the other shows 16384K/2048K
> ,why?I use the same version ios
Your revision D router has an additional 2MB soldered to the mainboard.
See comments below.
> the above is the output:
>
> cisco 2522 (68030) processor (revision M) with
> 14336K/2048K bytes of memory.
> Processor board ID 11370986, with hardware revision
> 00000003 Bridging software.
>
> cisco 2511 (68030) processor (revision D) with
> 16384K/2048K bytes of memory.
> Processor board ID 02383484, with hardware revision
> 00000000 Bridging software.
Early 2500s had 2MB of RAM on board, and could run earlier IOS with
some configurations with only this RAM, and no SIMM in place. If you
add the SIMM, then the SIMM would be used for main processor and the
onboard for shared I/O. With no SIMM, the on-board would be split
1MB and 1MB. These routers could have a total of 18MB, 16 in the SIMM
plus 2 onboard.
At Revision "I" of the hardware, it bacame obvious that 2MB would no
longer be adequate in most cases, and thus a SIMM would be required.
At that point Cisco stopped populating the mainboards with the 2MB.
So, the newer routers always require a SIMM and support a maximum of
16MB. This is allocated logically between processor and I/O at boot.
Gory details here:
http://www.cisco.com/warp/public/63/arch_2500_5750.shtml#memory
-- Jay Hennigan - CCIE #7880 - Network Administration - jay@west.net NetLojix Communications, Inc. - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323
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