Remote IOS Upgrade

[patni_systems]

Hi Guys,

Normally when I upgrade the IOS image of my Cisco Router, I boot it in ROMMON mode, and then do the upgrade activity.

I have a special requirement for which, I have to remotely upgrade the IOS without console access to a Cisco box. Flash capctiy of the router is not enough to hold both the old and new image, so when I load the new IOS image, my old one will be deleted.

Can someone tell me how this can be done with only a telnet connection to the router?

Best Regards

Nandan

[pkhatri]

Hi Nandan,

As long as it's not a run-from-flash router like a 2500, you can reasonably safely delete the old image on the flash without affecting the operation of the box. Once you do that, you can then copy the new one over and then reboot the box to make it come up with the new IOS. There's still a possibility that the router may come back after the reboot and there is absolutely nothing you can do to reach it via telnet if that happens. You will need to have out-of-band connectivity if that happens.

However, as I said, you should just be able to delete the old image and copy the new image and reboot the box, following which you can telnet back into it.

Hope that helps - pls rate the post if it does.

Paresh

[ewang]

You can surely tftp remotely an IOS to router while older IOS is being erased. You just need to ensure new IOS is not corrupted in the process, or use ftp which runs on tcp

[Richard Burts]

I have updated the IOS on remote routers many times. There is a safety factor if the router flash is large enough to hold two images, but as was pointed out in an earlier post, as long as the router is not run from flash router you can delete the IOS in flash without impacting the running router.

You will use the copy command to do the remote upgrade. You will telnet to the router, get into enable mode, and issue the copy command which will do the upgrade.

Depending on the router model, most routers in the copy process will check to see if there is room in flash and will prompt asking if you want to erase flash. If the router does not prompt then you may need to manually erase the existing image.

The IOS supports several transports in the copy command. You can do copy tftp: flash: or you can copy ftp: flash: In doing the upgrade on a remote router I would suggest that using ftp is better than using tftp (assuming that you have an ftp server as well as a tftp server). I find the file transfer time is shorter with ftp than it is with tftp (and in doing a remote update quicker is better).

HTH

Rick

[gschertz]

Nandan, I have upgraded a lot of cisco routers remotely on networks I manage. As long as it is not a run from flash, you have ethernet connectivity for a tftp program to load the IOS it is faily safe. BE sure to varify the flash and ram are enought to run the new IOS!! the last thing you want to happen is when you reboot there is not enough ram to run the IOS!!.

On the 1700,2600 when you tell the router to load the IOS to flash it will erease the flash before loading the new IOS. the newer routers you can delete the old IOS then load the new one (example the 2800 series) and then reboot the routers.

If you have a spare or a simmilare product in the shop you can test with that to become familare with the process.

Basic command is copy tftp flash

and the router will prompt for the rest. I use pumpkin as a tftp server for this process.

Gene

[jdewing]

One final you should do is enter the reload in (# of minutes) command. While this wont necessarily save you if things are corrupted, it is a necessary back door that MAY increase your chances of getting back into the router should the process fail.

[Richard Burts]

While I am a strong advocate of scheduled reload when making config changes on a remote router, I think that scheduling a reload when you are erasing flash and loading a new IOS is very dangerous and I would argue against it. The scheduled reload in making config changes will undo any changes you may have made and return the router to its original state (potentially a good thing). But when erasing flash and loading a new IOS it could make the router reload part way through the download (especially if the download takes longer than you thought it would).

So I say scheduled reload is a good suggestion for some situations but not for the topic of this post.

HTH

Rick