I am afraid that your router is probably experiencing a hardware problem. I am not sure if the NVRAM memory in 3660 is physically distinct from FLASH or if it can be influenced by problem with FLASH, but your problem also encompasses the FLASH memory, as the router is not able to access it and load the IOS stored there.
Is it possible for you to enter the ROMMON mode and try to download the IOS file back to the FLASH using the tftpdnld command? The following URL contains a discussion how to use this command. It is written for 2600 series routers but I believe that the 3600 will work in the same way.
If you manage to load and boot the IOS, try to issue the commands erase startup-config and copy running-config startup-config to reinitialize the NVRAM and to store data there. If this does not work, then I am afraid there is not much more you can do.
There was no IOS on the flash of the router model 3660. We are trying to download with xmodem. Since it is very slow could you tell me the cmd syntax for the ymodem command. I tried it as xmodem -cyrx iamge_name. Pls give the correct syntax.Also we tried to do the 'dnld" cmd for the tftp download.
Please give the correct syntax. It is gives timeout error after entered all config entries.
Pls confirm me the IP address we use in tftpdnld process is the PC IP address where the console is being used or any unique IP address.
How to ping the gateway IP from the ROMmon console>.
If possible, do not download the IOS over the XModem and the console - that will take ages.
Proceed via the following steps:
Turn on the router and enter the ROMMON mode.
Connect your PC's network card to the router's first Ethernet interface (i.e. E0/0 or Fa0/0) using a crossover cable.
Assign the IP address 10.0.0.1/24 to your PC's network card. Do not assign a gateway nor DNS.
Start the TFTP server on your PC and make sure that it contains the proper IOS in its directory for the router once it starts downloading it.
In the ROMMON mode of the router, enter the following commands exactly as they appear here, including the lower/upper case. You may directly copy and paste them but of course change the image file name. Do not use the TAB key or the arrows to move on the command line in the ROMMON. If you make a typo, use only the backspace to delete the line. If you hit the TAB or any of the arrow keys, the entire command will be rejected by the router as unknown and you will have to type it again completely anew after hitting Enter.
To explain what's going on here: The router will be assigned the IP address 10.0.0.2/24. Your PC will serve both as a default gateway for the router (this is only formal - the gateway has to be set but because your PC is running the TFTP server as well, there is no need to use the gateway) and as the TFTP server. Hopefully, this setup will allow you to download the proper IOS back to the FLASH of your router.
You cannot ping an IP from the ROMMON. Regarding the networking support, the ROMMON has almost no network support at all.
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