This document explains how to download a software image to a Cisco 2600/2800/3800 Series Router using Trivial File Transfer Protocol (TFTP) over the first LAN port using the ROMmon tftpdnld command.
There are no specific requirements for this document.
This document is not restricted to specific software and hardware versions.
Refer to Cisco Technical Tips Conventions for more information on document conventions.
First, you must set ROMmon environment variables prior to the TFTP download. All variable names are case sensitive.
You can view the ROMmon environment variables by using the set command, as shown here:
rommon 3 > set PS1=rommon ! > IP_ADDRESS=172.18.16.76 IP_SUBNET_MASK=255.255.255.192 DEFAULT_GATEWAY=172.18.16.65 TFTP_SERVER=172.18.16.2 TFTP_FILE=quake/rel22_Jan_16/c2600-i-mz
The variables to set for tftpdnld are shown here:
usage: tftpdnld [-ur] Use this command for disaster recovery only to recover an image via TFTP. Monitor variables are used to set up parameters for the transfer. (Syntax: "VARIABLE_NAME=value" and use "set" to show current variables.) "ctrl-c" or "break" stops the transfer before flash erase begins. The following variables are REQUIRED to be set for tftpdnld: IP_ADDRESS: The IP address for this unit IP_SUBNET_MASK: The subnet mask for this unit DEFAULT_GATEWAY: The default gateway for this unit TFTP_SERVER: The IP address of the server to fetch from TFTP_FILE: The filename to fetch The following variables are OPTIONAL: TFTP_VERBOSE: Print setting. 0=quiet, 1=progress(default), 2=verbose TFTP_RETRY_COUNT: Retry count for ARP and TFTP (default=7) TFTP_TIMEOUT: Overall timeout of operation in seconds (default=7200) TFTP_CHECKSUM: Perform checksum test on image, 0=no, 1=yes (default=1) Command line options: -r: do not write flash, load to DRAM only and launch image -u: upgrade the rommon, system will reboot once upgrade is complete rommon 14 >
Note: As detailed in Cisco bug ID CSCdk81077 (registered customers only) , for Cisco 2600 and 1720 Series Routers running the ROM monitor command tftpdnld, the command might report a bad checksum comparison when it loads Cisco IOS software images of Cisco IOS Software Release 12.0(2.2)T or later.
Note: As a workaround to this problem, set the ROM monitor variable TFTP_CHECKSUM to 0. This is done by defining the variable TFTP_CHECKSUM=0 from the ROM monitor setcommand, and then proceeding with the tftpdnld procedure.