Disaster Recovery with TFTP Download
The standard way to load new software on your router is using the copy tftp flash privileged EXEC command from the Cisco IOS software command-line interface (CLI). However, if the router is unable to boot the Cisco IOS software, you can load new software while in ROM monitor mode.
This section tells how, in ROM monitor mode, to download a Cisco IOS software image from a remote TFTP server to the router Flash memory. Use the tftpdnld command only for disaster recovery because it erases all existing data in Flash memory before downloading a new software image to the router.
Note A 10BASE-T Ethernet Port is not active in ROM monitor mode and, thus, cannot be used for TFTP download. The Cisco 1700 modular routers do not support the WIC-1ENET card in ROM monitor mode.
TFTP Download Command Variables
This section describes the system variables that can be set in ROM monitor mode and that are used during the TFTP download process. There are required and optional variables.
Note The commands described in this section are case sensitive and must be entered exactly as shown in the lists.
Required Variables
The following variables must be set with the commands shown before using the tftpdnld command:
Variable
Command
IP address of the router.
IP_ADDRESS= ip_address
Subnet mask of the router.
IP_SUBNET_MASK= ip_address
IP address of the default gateway of the router.
DEFAULT_GATEWAY= ip_address
IP address of the TFTP server from which the software will be downloaded.
TFTP_SERVER= ip_address
The name of the file that will be downloaded to the router.
TFTP_FILE= filename
Optional Variables
The following variables can be set with the commands shown before using the tftpdnld command:
Variable
Command
Whether or not the router performs a checksum test on the downloaded image:
1-Checksum test is performed.
0-No checksum test is performed.
TFTP_CHECKSUM=setting
Number of times the router attempts ARP and TFTP download. The default is 7.
TFTP_RETRY_COUNT= retry_times
Amount of time, in seconds, before the download process times out. The default is 2400 seconds (40 minutes).
TFTP_TIMEOUT= time
Configures how the router displays file download progress.
0-No progress is displayed.
1-Exclamation points (!!!) are displayed to indicate file download progress. This is the default setting.
2-Detailed progress is displayed during the file download process. For example:
Initializing interface.
Interface link state up.
ARPing for 1.4.0.1
ARP reply for 1.4.0.1 received. MAC address 00:00:0c:07:ac:01
TFTP_VERBOSE= setting
Using the TFTP Download Command
The steps described in this section should be performed while in ROM monitor mode.
Step 1 Use the appropriate commands to enter all the required variables and any optional variables.
Step 2 Enter the tftpdnld command as follows:
rommon 1 > tftpdnld [ -r ]
Note The -r variable is optional. Entering this variable downloads and boots the new software but does not save the software to Flash. You can then use the image that is in Flash the next time you enter the reload command in the Cisco IOS software CLI.
You will see output similar to the following:
IP_ADDRESS: 10.0.0.1
IP_SUBNET_MASK: 255.255.0.0
DEFAULT_GATEWAY: 1.3.0.1
TFTP_SERVER: 223.255.254.254
TFTP_FILE: c1700-bnr2sy-mz.070298
Invoke this command for disaster recovery only.
WARNING: all existing data in all partitions on flash will be lost!
Do you wish to continue? y/n: [n]:
Step 3 If you are sure that you want to continue, enter y in response to the question in the output:
Do you wish to continue? y/n: [n]:y
The router will begin to download the new file.
Pressing Ctrl-C or Break stops the transfer before the Flash memory is erased.
