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Re: Thanks WAS: any cisco experienced...

  • From: barton
  • Date: Tue Sep 29 22:16:58 1998

Sorry if this is the wrong topic for NANOG but some mis-information
needs to be fixed before it spreads any further.

>I appreciate the assistance several of you provided.  As it turns out the
>image that was installed on the flash was a compressed image only for the
>1605, and not for the 1601-1604 routers.  It looks like someone at RMA
>inadvertantly loaded the wrong software to flash, and it ended up throwing
>most off guard.  I knew it had to be something simple.

WRONG, WRONG, WRONG. NOT just for 1605.

It is a perfectly fine image and one I would routinely recommend for any
1601-1604 user, but you *MUST* understand the implications of running
it.

You don't mind running about 35% faster, I would assume, as that is 
what you can now do.

You have loaded an image that has to load into DRAM and then self 
decompresses. Multiple 3rd party toolkits do this routinely for 
25xx routers if someone needs more squeeze that an Unix .Z image
provides to wedge a recent IOS into FLASH.

Sadly the 1601's bootstrap has a **BUG** that precludes running mere
.Z images, but then cisco came out with the 1605 and with it came
cisco provided -mz images - to everyone's joy.

The 1601-1604 have only 2 meg soldered in, so adding a 16 meg non-parity
simm ($15 or so these days) only gets you to 18 meg. Not enough
for the monster largest images and still leave enough for buffers and
tables. Marketing decided to not let the customers only needing some
smaller image know you can just as well run from DRAM. Usual cisco arrogance.
"keep them stupid - they still pay $1000 for 16 meg DRAM which proves it"

So they made the 1605 with 8 meg soldered in. That with a 16meg SIMM is 
enough to run any image in DRAM and still leave enough for other things.

BUY A $15 (or $25 if someone is ripping you off, or $1000
if you are being "ciscoed") 16 meg DRAM simm and your box with the
-mz image will not only boot but will run 35% faster than running
from FLASH.

And, with FLASH left (READ/WRITE), updates are trivial on a running
router.

This has been rehashed repeatedly on c.d.s.c. Check an archive.

>For the record in the 1600-series world..  images with c1600-mz* are
>compressed and will only work on the 1605 model.

NO NO! - only will work in a 16xx router with adequate DRAM, but since
you can MAX that box for a $15 16 meg DRAM SIMM, this is hardly
a problem.

>Images with c1600-l* are for the 1601-1604 models and are not compressed.

Unless someone uses one of the available toolkits to make a -mz. Using 
a unix compressed .Z image ***SHOULD*** be ok but there is a good 
old fashioned *BUG* is their boot code. The TAC says so, too (I can probably
dig out an old case number if really pressed).

Now that cisco ships the -mz images for 1605s, every 16xx should be 
running them. Many many 25xx users run .Z or -mz images and
cisco's code says "wrong image type" which everyone doing this
simply ignores.




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