3-12
Catalyst 2948G-L3 and Catalyst 4908G-L3 Software Feature and Configuration Guide
78-10408-01, Cisco IOS Release 12.0(7)W5(15d)
Chapter 3 Initial Switch Router Configurations
Recovering a System Image Using Xmodem and Ymodem
To copy a Cisco IOS image from a computer or workstation to a router using the Xmodem or Ymodem
protocol, use the following commands:
The computer from which you transfer the Cisco IOS image must be running terminal emulation
software and the Xmodem or Ymodem protocol.
Xmodem Transfer Example Using the ROM Monitor
This example shows a file transfer using the ROM monitor and the Xmodem protocol. To transmit with
the Ymodem protocol, use the xmodem -y command.
The Catalyst 2949G-L3 and the Catalyst 4908G-L3 switch routers must have enough DRAM to hold
the IOS image file being transferred. The transferred IOS image runs only in DRAM and cannot be
stored in boot flash memory. Once your switch router boots up with the transferred image, you can copy
a good IOS image from a TFTP server onto the boot flash file system.
Caution A modem connection from the telephone network to your console port introduces security
issues that you should consider before enabling the connection. For example, remote users
can dial into your modem and access the router’s configuration settings.
To download an IOS image from ROM monitor (using the Xmodem and Ymodem protocols), use the
following steps:
Step 1 Place a Cisco IOS software image on the remote computer’s hard drive. You can download an image
from Cisco Connection Online.
Step 2 Transfer either from a remote or a local computer.
• To transfer from a remote computer, connect a modem to the console port of your switch router and
to the standard telephone network. The modem and console port must communicate at the same
speed, which can be from 1200 to 57600 bps, depending on the speed supported by your modem.
Use the confreg ROM monitor command to configure the console port transmission speed for the
switch router. You can also set the transmission speed with the -s option.
Note We recommend that you use the maximum speed of 57600 bps.The size of an IOS
image is approximately 3MB and takes about 10 minutes to transfer at 57600 bps.
Connect a modem to the remote computer and to the telephone network. The remote computer dials
through the telephone network and connects to the router.
Command Purpose
xmodem [-c | -y | -s ] Copies a system image from a computer to DRAM
using the ROM monitor.
The -c option provides CRC-16 checksumming;
-y uses the Ymodem protocol;
and -s sets the console port data rate or speed.
Speeds range from 1200 bps to 57600 bps.
