We have a router in which we dont have much memeory to keep the existing IOS and upload the new IOS.
i have to delet the old ios and upload the new.
my question? how much time it will take to upload the new ios using the console connection.
please help, any suggestion would be highly appreciated. Thanks in advance.
No the telnet session would not disconnect just because you deleted the old IOS.
Perhaps it would help to be clear that flash is where the code is stored that is loaded and executed at boot time. After the code is loaded then the router will continue to run the code no matter what happens in flash. so you can easily delete the image in flash and load another image and that will not impact the running of the router.
However you should be aware that there is some risk in doing this. If there is any problem in loading the code over the network there could be a problem. And if the router should reload (power cycle or whatever) before the new code is loaded then the router would not be able to load code and run - and recovery over the network is more challenging. So you should be aware of these risks as you make the decision to erase the image from flash and then to load a new image over the network.
I do not want to be alarmist or to give too negative an impression. I frequently do erase images and load code over the network. And you can do this also. But I just want to be sure that you understand the possible problems as you make your decision.