cisco 3900 series router not Xmodem

[Basavaraj Ningappa]

Hi Team,

Needed some advice here

We have one scenario in which we are using Cisco 3900 series router and some how router got corrupted. We tried using tftpnld for loading the IOS again and we are not able to load the IOS. I'm thinking of using XMODEM and tranfer the file but surprisingly this router not supporting XMODEM on the rommom mode.

Can anyone help me how can we enable XMODEM transfer on the cisco 3900 series router ?

[Peter Paluch]

Hello,

I am surprised at the notion that 3900 series no longer support XMODEM - how did you come to that conclusion?

Anyway, with a bit of luck, you could try using an USB flash stick to boot from. Try to format it using either FAT16 or FAT32 on a PC, copy the IOS image onto the USB stick and then in ROMMON try using the boot usbflash0: command:

http://www.cisco.com/c/en/us/td/docs/routers/access/1900/software/configuration/guide/Software_Configuration/appendixCrommon.html#pgfId-1014725

You may want to test a couple of different USB flash stick vendors and sized as ROMMON can be picky about the particular type.

Best regards,
Peter

[Basavaraj Ningappa]

Thank you peter for your response.....

if you see the below help output from the rommon mode, you dont see the xmodem feature in this router.

rommon 3 > help               
alias               set and display aliases command                                                   
boot                boot up an exte                                  
break               set/show/clear the breakpoint                                                 
confreg             configuration register utility                              
cont                continue executing a downloaded image
context             display the context of a loaded image
cookie              display contents of motherboard cookie PROM in hex
dev                 list the device table
dir                 list files in file system
frame               print out a selected stack frame
help                monitor builtin command help
history             monitor command history
iomemset            set IO memory percent
meminfo             main memory information
repeat              repeat a monitor command
reset               system reset
rommon-pref         Select ROMMON
set                 display the monitor variables
showmon             display currently selected ROM monitor
stack               produce a stack trace
sync                write monitor environment to NVRAM
sysret              print out info from last system return
tftpdnld            tftp image download
unalias             unset an alias
unset               unset a monitor variable
hwpart              Read HW resources partition

I have also tried with few CF's but these didnt work for me :( they didnt detect in the router itself.

I have few questions...

If i want to use TFTPDNLD should i use only cross-over cable or it will also work with staright cable ?

basically how this tftfdnld works ?

Thanks

Basavaraj

[Peter Paluch · Accepted solution]

Basavaraj,

Okay, I see. So you are saying that the USB (not CFs) flash drives did not work? Have you tried dir usbflash0: on each one of them?

The tftpdnld should be fairly easy to use, though, provided you can easily set up a TFTP server.

i want to use TFTPDNLD should i use only cross-over cable or it will also work with staright cable ?

I am not sure if the 3900 router has Ethernet ports that support auto-MDIX. However, most PCs today do, so I would believe that a straight-through cable would be working. It is sufficient to have one link partner to support the auto-MDIX feature.

basically how this tftfdnld works ?

It allows you to download an IOS available over the TFTP server from a specified IP address, then either store it into the FLASH directly, or just load it to RAM and start it from there. I personally suggest downloading the file only to the RAM and when the router boots, use the normal copy command to download the file from the TFTP once again and store it into the FLASH. The reason I suggest this is that the tftpdnld usually formats the CF card if told to store the IOS image there, and it uses an old filesystem format when doing this. It is better to format the CF card using a FAT filesystem but this format is only supported when a full IOS is running.

Therefore, after you set up a TFTP server on your computer and connect it to the Gi0/0 interface of your router, issue the tftpdnld -r command (-r says "copy to RAM and run"). Most certainly, the router will tell you that you need to set up a series of environment variables that define the router's address, mask, gateway, TFTP server address, and TFTP file. Please define them by entering them in the ROMMON CLI, one by one, as follows (this is of course just an example):

IP_ADDRESS=10.0.0.1
IP_SUBNET_MASK=255.255.255.0
DEFAULT_GATEWAY=10.0.0.2
TFTP_SERVER=10.0.0.2
TFTP_FILE=c3900-blah-blah.bin

Then enter the tftpdnld -r again. The download should start.

You can find additional details here:

http://www.cisco.com/c/en/us/td/docs/routers/access/1900/software/configuration/guide/Software_Configuration/upgrade.html#pgfId-1054647

Best regards,
Peter

[Basavaraj Ningappa]

HI Peter,

do you have any idea why 3900 series router not supporting x-mmodem ?

or is there anyway we can enable it from rommon mode ?

[Peter Paluch]

Hello Basavaraj,

I would believe that the XMODEM is a fossil of times long past, and its usability is extremely limited. IOS images for the 3900 series routers are almost 100 MB large. As the console port can be configured for 115.2 kbps max, downloading an IOS image over XMODEM will take hours. It just does not make sense to run it over XMODEM now that every PC and every notebook has a network connection and can be set up with a TFTP server easily.

That would be my personal explanation on why the XMODEM support on 3900 series routers appears to be dropped.

Best regards,
Peter