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User cannot get into ROMmon mode to download a Cisco IOS Software image into the router

Core Issue

The Xmodem software download procedure can be used when there are no TFTP servers or network connections and a direct PC connection (or modem connection) to the router's console is the only viable option. 

Because this procedure relies on the console speed of the router and the serial port of the PC, it can take a long time to download an image. For example, it takes approximately 25 minutes to download the Cisco IOS  Software Release 12.1(16) IP Plus image to a Cisco 1600 series router using a speed of 38400 bps.

Resolution

To get into ROM monitor (ROMmon) (rommon 1>) mode, perform these steps: 

  1. Launch a terminal emulator program.
  2. Configure Windows Hyper Terminal for 8-N-1 at 9600 bps and connect your PC's serial port to the console port of the router.
  3. Once connected, get into the ROMmon prompt (rommon 1>).
    • Typically, if the router's Cisco IOS Software image and bootflash image are both corrupt, the router only comes up in ROMmon mode.
    • If the router's Cisco IOS Software image and bootflash image are not corrupt, and you need to get into the ROMmon prompt, change the configuration register to 0x0, as shown in this example. The configuration register is typically 0x2102, as shown in the output of the show version command.
      1600#configure terminal
      Enter configuration commands, one per line.  End with CNTL/Z.
      1600(config)#configure
      1600(config)#config-register 0x0
      1600(config)#^Z
      1600#
      00:22:06: %SYS-5-CONFIG_I: Configured from console by console
      1600#reload
      System configuration has been modified. Save? [yes/no]: n
      Proceed with reload? [confirm]
      00:22:16: %SYS-5-RELOAD: Reload requested
      System Bootstrap, Version 12.0(3)T, RELEASE SOFTWARE (fc1)
      Copyright (c) 1999 by Cisco Systems, Inc.
      
      Simm with parity detected, ignoring onboard DRAM 
      C1600 platform with 16384 Kbytes of main memory
      rommon 1 >

For a complete list of steps on how to perform an Xmodem software download, refer to Xmodem Console Download Procedure Using ROMmon.


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