September 29th, 2005, 07:48 PM
CISCO Router lab issues
I am helping out with a CISCO class at my high school. We are running a lab with CISCO series 1600 and 1700 routers. Every once in a while, one of these routers will turn up without a IOS image. Do you guys think this is a "evil" kid, or just an accident. If the latter, what commands could accidently delete the IOS from flash?
September 29th, 2005, 09:07 PM
It is very easy to erase the IOS from flash...
Copying a file from a tftp server will prompt you to erase the flash.
You have to tell it "n". If you just press "enter" then bye bye flash contents.
Here is an example:
Even something as simple as "erase flash:" will do it.
router#copy tftp flash:
Address or name of remote host [192.168.x.x]?
Source filename [test.txt]?
Destination filename [test.txt]?
Erase flash: before copying? [confirm]n
Loading test.txt from 192.168.x.x(via Ethernet0): !
[OK - 4 bytes]
Verifying checksum... OK (0x1826)
4 bytes copied in 0.048 secs (83 bytes/sec)
Restoring an IOS is rather quick and easy using ROMMON and TFTP.
Erasing the flash filesystem will remove all files! Continue? [confirm]n
Its slow and painful if you're trying to do it via xmodem or ymodem...
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September 29th, 2005, 10:17 PM
Yep, happens a lot on my lessons! Usually after ive been taking them through backing-up to a TFTP server! You really have to stress the "N" that goes after the erase flash before copying prompt!
It is highly unlikley that it is a fault in the router if it only happens every now and then - but i suppose it is possible.
AND - when I finished the practical part of a lesson I have an ACL I enable that will deny all traffic exept from my machine to the routers - you always get some smart-ass who thinks its funny to erase the flash memory or change the paswords etc which usually results in me missing my most of my lunch!
September 30th, 2005, 01:25 PM
Thanks a lot guys! I have installed tftp servers on all of our lab stations, but knowing what can cause this problem will make things a lot easier. And thanks for the quick response!