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New Member

Loading IOS from TFTP on 2500, where the router store the image for exec?

Hello,

My question is: the 2500 series routers, generally, have a flash memory where resides the IOS software image, so, this series execute IOS directly from flash memory, this model does not load the software image from flash to RAM...

Well... when the 2500 loads a IOS software image from TFTP (not from flash)... where this device store the software image to execution????

Sds

Jefferson

7 REPLIES
Bronze

Re: Loading IOS from TFTP on 2500, where the router store the im

Jeff,

Both 1600 and 2500 series are run-from-flash routers which means it will execute image on flash no matter where it loads from.

Ming

New Member

Re: Loading IOS from TFTP on 2500, where the router store the im

OK Minie...

but, when this router loads a image from a TFTP Server.... for example using the command

boot system tftp .....

where this router will store this image for execution?

I read that the router will store the image in the RAM, so a little memory will be free for other process....

this is true?

Look this.. read this part:

"Before setting up your router to boot from a TFTP server, you must do the following:

Understand that booting from a TFTP server consumes more dynamic RAM (DRAM) than booting from Flash memory. The amount of DRAM lost is equivalent to the software image size and is displayed when the router boots."

http://www.cisco.com/en/US/products/hw/routers/ps380/products_configuration_guide_chapter09186a008007c98d.html

New Member

Re: Loading IOS from TFTP on 2500, where the router store the im

Adding...

Imagine a router that will run-from-tftp..... so...when the router boots... it will download the image from TFTP to ????

I think that will download the image to RAM... so a smaller free RAM memory will be available to other proces...

correct?

Bronze

Re: Loading IOS from TFTP on 2500, where the router store the im

You raised a good point. Remember, the image with "l" in it is a run-from-flash image and is not compressed. It's designed to be saved on flash memory and run from there.

The RAM in 2500s are only for I/O data, it's not designed to run IOS image. And boot from tftp will attemp to load the image into DRAM and it will fail. So, to correct my previous reply a little bit that boot run-from-flash image over network will not work.

HTH,

Ming

Bronze

Re: Loading IOS from TFTP on 2500, where the router store the im

I guess never say never. Guess what, Jefferson, you are absolutely right. Once I tried on a router with larger DRAM, it works just fine.

Even thought the image claims as run-from-flash image, it works just fine in DRAM. The catch is, the now DRAM size needs to be "required image size + required DRAM size". The first one is for process memory and second one is need for I/O data. I even erase the flash totally to test if the image still relies on Flash, and nothing happened. And the beauty is flash is now "read/write", and since image runs from DRAM, it's much faster.

Thanks for raising this question. It's very good one.

Ming

New Member

Re: Loading IOS from TFTP on 2500, where the router store the im

Well Ming...

living and learning...

Yet on this question....

if the 2500 series has the resource of run IOS from DRAM... why it run IOS from flash, that is very slower???

Bronze

Re: Loading IOS from TFTP on 2500, where the router store the im

I agree. I guess at the time 2500s were introduced, DRAM is still a big deal.

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