Loading IOS IMage on router without sufficient memory

[dvaggalis]

I have a 3640 router with 16M flash and 28M DRAM. I want to upgrade to a new IOS image but the requirements are 16M flash and 32M DRAM.

Can I get away with loading the new image, even though I don't meet the minimum requirements?

[michael-faust]

No

[dvaggalis]

No, because the router will recognize there is not enough memory and will not complete the boot cycle?

Or it will boot, but not perform efficiently?

[mpervere]

Actually, you MIGHT get away with it (for a while). With FLASH no, but with DRAM maybe. At least that's true on the 2600 (I have at least one over-IOS'ed right now), and I assume also with the 3600.

It really depends on what image you're using, what features of it you're using, how much traffic is being processed, what routing protocols are running, etc. The problem is, you might get away with it for a while, until you start to run up the traffic volume or implement some more complex, memory-intensive function, at which point the router starts to flake out when you can least afford the down-time. Consider though that the same features that caused you to want to upgrade are quite likely the same features that cause you to need more RAM (or you wouldn't be doing the upgrade).

Oh yeah, you probably won't get real far with TAC, if you're running an IOS on an under-DRAM'ed router.

Mike