I have Cisco 2610 and it has version 12.0.

I want to upgrade to 12.3

The DRAM is 32MB and Flash is 2 slots of 8MB and 8MB.

Which IOS to get that fits in 8MB with 12.3?

2 Answers 2


If you can't find 12.3 image that fits in the 8MB flash partition, you'll need to repartition the flash with no partition flash in the configuration mode. Then format it as one big partition, which should give you 16MB of space, and finally put some 12.3 IOS image on it which should then work fine.

Ah, and BTW, the IOSes tend to reserve some space, and if you're fighting with pushing every available bit to use, erase the flash in this manner:

erase /no-squeeze-reserve-space flash:

  • you saved my day man. thank you very much. din't knew if we can combine them
    – Mirage
    Mar 30, 2014 at 11:12
  • i get this when i load new image Smart Init is disabled. IOMEM set to: 15 Configured I/O memory percentage was too large. Using 10 percent iomem. and Smart-init will be disabled and new I/O memory size will take effect upon reload.
    – Mirage
    Mar 30, 2014 at 12:40
  • That's "normal". IOMEM is trying to set proper amount of RAM with regards to the new IOS version. Mar 30, 2014 at 17:11

A more generic answer first: Check which downloads are available for your device.

On http://software.cisco.com/download/navigator.html you can search for your device and see which downloads are available and how much Flash/RAM they need.

You don't need a login or special access rights to access these pages. And yes the web site is sometimes confusing.

I just did for the 2610 and 12.3 is only listed under "Deferred Releases".

  • i tried but i am not able to download. there is lock and says service contract required. how can i download it
    – Mirage
    Mar 30, 2014 at 11:36
  • You didn't ask for a download just which version you can install. ;-) In order to download Cisco software image you need a Cisco CCO account (easy part, just create one) and a valid service contract for the device (hard part because a 2610 is rather old). One thing that might work is asking Cisco to provide a new image because of a security vulnerability. You need to find an advisory for your platform and follow the instructions provided there.
    – user2084
    Mar 30, 2014 at 15:08

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