Can you install an IOS without the recommended ram and flash?

Cubuntu28

Can you install and have the router run slow in a lab environment, or will I be forced to upgrade the ram and flash in order to install the IOS I want?

If anyone is wondering I ordered a couple of 3640s and a 2950switch. I do not have the specs in front of me, but I know they are not maxed out. I was so sick of not committing to some hardware, I decided to just buy something, and figure it out as I go along, and learn even if it meant the hard way.

Thank you,

Roguetadhg

No.

The size of the IOS usually is what required. For example a 16 MB IOS won't fit on a router with 8 MB Flash.

IOS's also differ with model numbers. It's just not a good idea.

You'll have to look at the specs with a /show ver. as well as look at the cisco documentation to figure out what is the maximum. It's decently cheap, so it's not a major investment

jdballinger

CAN you install it? If you have enough flash memory, yes you can. Will it RUN if you don't have enough RAM? No, not at all. This was one of my first mistakes I made when I got me initial routers for my lab. I wasn't paying close enough attention and installed an image I did not have enough RAM for on my beefiest router. It transferred just fine from my TFTP server to the router, and I did a reload. Upon reload however, it entered an infinite loop where it would POST, get half way through expanding the IOS image, and then fail out because there wasn't enough RAM. Rinse lather repeat.

Basically, unless you want to end up having to spend like 4 hours doing an XMODEM transfer of a correct image back onto your device, pay attention to the memory and storage requirements! They really are there for a reason!

MAC_Addy

jdballinger wrote: »

CAN you install it? If you have enough flash memory, yes you can. Will it RUN if you don't have enough RAM? No, not at all. This was one of my first mistakes I made when I got me initial routers for my lab. I wasn't paying close enough attention and installed an image I did not have enough RAM for on my beefiest router. It transferred just fine from my TFTP server to the router, and I did a reload. Upon reload however, it entered an infinite loop where it would POST, get half way through expanding the IOS image, and then fail out because there wasn't enough RAM. Rinse lather repeat.

Basically, unless you want to end up having to spend like 4 hours doing an XMODEM transfer of a correct image back onto your device, pay attention to the memory and storage requirements! They really are there for a reason!

I did exactly the same thing. Very frustrating indeed. Lesson learned. Experience gained.

xXErebuS

jdballinger wrote: »

CAN you install it? If you have enough flash memory, yes you can. Will it RUN if you don't have enough RAM? No, not at all. This was one of my first mistakes I made when I got me initial routers for my lab. I wasn't paying close enough attention and installed an image I did not have enough RAM for on my beefiest router. It transferred just fine from my TFTP server to the router, and I did a reload. Upon reload however, it entered an infinite loop where it would POST, get half way through expanding the IOS image, and then fail out because there wasn't enough RAM. Rinse lather repeat.

Basically, unless you want to end up having to spend like 4 hours doing an XMODEM transfer of a correct image back onto your device, pay attention to the memory and storage requirements! They really are there for a reason!

GUILTY and it stinks! Mine wasn't due to this reason; If I remember correctly I deleted the image to upgrade b/c the new was too large to fit both and someone tripped over the power and unplugged it before transfer of new image =(.

Legacy User

You could but once you try to run it, it will crash and probably going into an never ending reboot cycle.

networker050184

You can store the IOS on a TFTP server and boot from there. Not recommended for production, but probably not too bad for a lab.

Corndork2

As others have said, you must have the required amount of FLASH. However, you can run some images without the reccomended amount of DRAM, however you should still be close to that amount.

For example, I have some router images that "require" 192M of DRAM, but I run them at 128M. The boot takes longer, and if you used it in production it would likely crash. But for a lab, it works just fine

networker050184

You don't need the required flash. You can store it on a remote server and boot from there.

Hondabuff

If you dont have enough RAM to run the IOS, you will brick the switch despite booting from a tftp. Then you have to boot into rom and reload the IOS from a tftp. Everyone should brick a Cisco Device just once for the experience.

oli356

Hondabuff wrote: »

If you dont have enough RAM to run the IOS, you will brick the switch despite booting from a tftp. Then you have to boot into rom and reload the IOS from a tftp. Everyone should brick a Cisco Device just once for the experience.

There isn't tftp in ROMmon mode is there? Or is there on routers but not switches or something?

jdballinger

You can TFTP from ROMmon, and that's the usual method of recovery. Unless of course you can't get a port configured for whatever reason, then you have to go the XMODEM method.

oli356

Was under the impression that switches didn't have it and have to use xmodem. Something I was told last week, also found http://www.cisco.com/en/US/products/hw/switches/ps628/products_tech_note09186a0080169696.shtml

I think that said to xmodem. It's 2:30 am, I'm on phone so don't want to double check!

JeanM

If it POSTs or boots to ROMMON it's not bricked

MAC_Addy wrote: »

Lesson learned. Experience gained.

+1 on that!

jdballinger

@oli356 You may be correct on that one. I have used XMODEM on both routers and switches, but now that I'm thinking about it I have only used TFTP from ROMmon on a router, 2621xm to be exact.