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November 2, 2006
Recovering IOS from ROMMON via TFTP
This information is here primarily for my reference at customer sites; for some odd reason, I seem to be recovering IOS images through ROMMON quite a bit lately. These are the minimum fields to get this going through TFTP rather than XModem.
rommon 1 > IP_ADDRESS=192.168.1.100
rommon 2 > IP_SUBNET_MASK=255.255.255.0
rommon 3 > DEFAULT_GATEWAY=192.168.1.1
rommon 4 > TFTP_SERVER=192.168.1.50
rommon 5 > TFTP_FILE=c2600-adventerprisek9-mz.124-5a.bin
rommon 6 > tftpdnld (this command kicks off the tftp download)
Posted by JC at November 2, 2006 3:39 PM
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Comments
When you do this, what interface is getting assigned the IP address? Does the router use the first Ethernet/FastEthernet interface?
Thanks,
Jeff
Posted by: Jeff at November 2, 2006 4:44 PM
Now THIS is handy to have! Thanks for the tip!
Jeff,
I may be wrong, and JC may correct me. But, I believe rommon builds it's own virtual interface, during the rommon session. When you leave the rommon session, you lose the configuration you made in it.
Cheers!
Aaron
Posted by: Aaron Paxson at November 2, 2006 6:34 PM
Yeah, it's the first LAN port (http://www.cisco.com/warp/public/471/76.html confirms this).
doing a "sync" (I think? check the rommon help) before the tftpdnld oughta make it remember the settings.
Posted by: cos at November 3, 2006 2:57 AM
I've used this same procedure to recover from an error of my own creation on my home lab. I only had one FE interface so I assume that the ip address would be assigned to the 0 interface (ie ethernet0, fe0/0).
Posted by: Dedan at November 3, 2006 11:34 AM
I believe this only works with an onboard fe interface. I had no luck on a 3640 that had nm interfaces in the past. Maybe I just got lucky with 2620xm. Way cooler than waiting on XModem. Like sledding on rocks to ice.
Posted by: David Lundgren at November 11, 2006 11:08 PM
It's funny you say that David - I just tried it on a 3640 and found the TFTPDNLD command missing from RomMon - I'd definitely say this is for routers that have a on-board FE interface.
Posted by: JC at November 12, 2006 3:42 PM
Did anyone catch my question/post about HSRP in the routing section? It's a little different since it applies to an ISP scenario. If I need to clarify the layout a little more for an answer I can do that.
Posted by: David Lundgren at November 13, 2006 8:17 PM
When assigning ip address in rommom of cisco router to which ethernet port the ip address will get assigned(If i had two ethernet port on my router)
Posted by: raghu at February 16, 2007 2:33 AM
Hey JC, I experienced exactly this. I couldn't find the command. But when I did a reboot on the machine, something odd happened. It seemed to download the image file after reboot.
Posted by: FR at April 13, 2007 1:39 AM
Thank yo very much. It did the work for me.
Posted by: Shams Iqbal at June 19, 2007 5:14 AM