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How to downgrade to 7.X from 8.X IOS on a Cisco Pix : Issue & Solution

This is about downgrading PIX Version 8.0(4) & ASDM 6.1(5) to PIX 7.2(4) and ASDM 5.2(4) but with only 64MB RAM and 16MB flash.


You have a Cisco Pix 515E which was running on PIX 7.2(4) and its supporting ASDM 5.2(4) without any issues with 64MB RAM and 16MB Flash. You upgrade it to 8.0(4) and ASDM 6.1(5).

1) You find that the Pix fails in applying a configuration or wont execute the packet trace utility once in a while. The memory usage would be 62MB out of 64MB.

2)You also cant upload old Pix 7.2(4) back as there is no space in Flash even after deleting the ASDM 6.1(5)

Issue and Solution

Pix 515E etc supports PIX IOS version 8.X and its supporting ASDM. The issue is PIX Version 8.0(4) & ASDM 6.1(5) needs 128MB memory to work efficiently . With 64MB, memory utilization will be high and usage wander around 62MB which can be an issue since 4MB is used for cache/buffering.

Another issue is you have only 16MB on your flash and you cant upload older IOS/ASDM to flash without deleting rest of files from Flash.
This is what I would suggest.

1)Upgrade to 128MB. Use a normal SD 64MB PC100 memory strip ( two strips). This will give  you enough memory to work ( you need buffer when you upload PIX 7.2(4) to Flash which your 64MB wont provide.

2) Boot up & please access via CLI .

3) Delete ASDM first so that you make space on Flash

4) Upload new IOS to Flash :- copy tftp: flash command

5) Make it the new boot image:- boot system flash:/pix724.bin (delete old one!)

6) Write and reboot

7) Delete 8.0(4) IOS from Flash

8) Upload new ASDM using the copy tftp: flash command.

9) Make it the default ASDM :- asdm image flash:/asdm-524.bin

10) Write and reload.


Comments (2)


Update; This is the solution ONLY if you cant buy the memory (SDRAM PC100, ideally 64MB X 2). I used memory from old PC and hence it's taller  which means you can't close the cover of the Pix. You will have to revert back to the 64MB memory that came with the Pix after you have successfully downgraded.
it is really a right way to downgrade to 7X from 8X IOS on Cisco pix issue

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