Cisco IOS Image Recovery via xMODEM

hello and welcome to life strings video-on-demand library my name is Matt George and in this video I will be discussing and demonstrating the Cisco IOS image recovery via X modem so there's three key points that I want to touch in this video prior to doing my demonstration which is when you'll be required to perform an X modem and how long an X modem takes as well as how you can speed it up and how you can change the bot rate of the device so let's going to get started here as you can see I have one big question here at the top of the slide which is when when would you be required to perform a X modem recovery and of course I've given three examples here in a slide with the first one being the number one reason which is a corrupt iOS image in flash let's say you go to work one morning and you receive several telephone calls and emails from end users on your network saying they cannot access resources on the network and after further investigation you discover that one of these switches mysteriously booted into rom monitor mode and of course you pursued the investigation and you discovered that the switch is failing to boot into Cisco IOS because it is crashing at the time that is extracting the image from flash into Ram and of course if you know the architecture of the iOS images you will know that most of your newer images are compressed so and if the CRC fails or something like that the switch or device will crash and instantly reboot and it will boot into rom monitor mode and of course the second example I've given here is the example that I personally have experience with which is an accidental flash erasure so one night I was working late for a client and I was in a hurry to get home because the season premiere of 24 was coming on television and I was typing really fast and I was wanting to get out of there so I typed in copy run tart and pressed enter twice really fast and I grabbed my console cable off the switch and threw everything in my bag and the next morning I go to work and I receive a few telephone calls saying that the network is down and of course after investigation I discovered that the flash is completely empty because when I pressed enter twice it erased the flash so pretty stupid a pretty stupid incident on my part but we all make stupid mistakes so and of course the last one being no image at all this is pretty common let's say if you purchase a used router or a switch off eBay and the company that you purchase it from has used sanitation procedures which erase the non-volatile Ram as well as the flash you will be required to x-mode the main image to the switch or specific router such as a 2500 or a 3600 of course with the 3600 you do have the option of booting the router from a PCMCIA flash card but if you do not have one of those on hand to you will be required to ex modem and image to the device so let's go ahead and continue here and this night I'm going to answer two of the common questions that everybody has about X modem which is how long it takes and how can you speed it up the default console baud rate for a Cisco device is 9,600 bits per second 9.6 kilobits per second and that means that it would take a four megabyte image file over 55 minutes 2x modem and an 8 megabyte image file would take over an hour and 51 minutes approximately 2 hours 2 X modem and of course you can't speed this up by setting the console baud rate to 115 kilobits per second or 115,200 bits per second whereas a 16 megabyte image file would take approximately 17 minutes 2x modem so how do you get the BOD rolling that is the best ever title for a slide to increase the baud rate of a Cisco device for a catalyst series switch you use the set bod variable under ROM monitor mode or for a Cisco router you would change the configuration register to 39 22 which increases the console baud rate to 115200 bits per second so let's go ahead and see the demonstration now you can see that I have my secured CRT window open and I have a console session established with this switch and in this demonstration I will be using a Cisco 3560 series catalyst which currently running 12 to 46 and for the purposes of this video what I'm going to do is erase the flash intentionally so I'm going to go ahead do that now and I'm going to pause the video here because it does take several moments alright now you can see the flash has been erased and I can go ahead and verify this by going that directory flash and now let me do is I'm going to go ahead and reload the switch and since the flash is empty the switch will automatically be forced into a rom monitor mode so let me go ahead and do that now I'm going to pause the video here and wait till the switch to go ahead and boot in the ROM monitor mode so this may take a few moments all right so now the solution is finished booting up and you can see that the switch did fail to boot into iOS obviously because the flash is empty but the first thing we need to do prior to attempting your next modem is set the baud rate to 115 kilobits per second if we don't do this then exploding me a 16 mega image remember would take over two hours so in order to set the baud rate we must use the set command which sets the environmental variables now typically you would probably see body equals 9600 but if you don't then it would default to 96 enter so what we need to do is set I'd keep in mind it is case sensitive so you have to type in all capital and 115 200 and soon as I press enter here you'll notice that I get all kinds of funny characters because soon as you press ENTER it does take effect immediately so what we need to do is disconnect from the serial console and edit the properties of the connection and change it up to 150 kilobits per second and reconnect back now you can see that I have access to the switch console again and if you look under the set environmental variables you'll be able to see the BOD is equal to 115 kilobits per second now so now we to go ahead and issue the copy command copy X modem to the flash and of course we have to give it a name so what I want to do is I'm going to minimize this and I already have the image that I want to export them so I'm going to right click to rename it and copy the name I just paste it here and type in bin as soon as I press enter it will ask me to go ahead and begin the expo so we need to go up here to transfer and CID X modem and go to the desktop and click on the image so now the switch has already initialized the X modem and you can see that it's starting to transfer here roughly about 6 kilobytes per second and yes to mate at time to completion is 25 minutes give or take so I'm going to pause the video here again and wait for this to complete and I will return after it's completed to continue alright as you can see here that my X modem transfer is just now finishing and so now we can go ahead and verify it and you can see that the image is indeed in flash alright first off we need to go ahead and set the console body right back to 9600 so in order to do this we use the unset command and soon as we issue that command you can see that does take effect immediately so I'm going to have to disconnect from the switch and change the baud rate of the connection here to 9600 and connect back to the switch and keep in mind that when you ex modem an image to a switch you may be required to change the boot parameters in order to view them you just use the set command and you can see that boot equals flash in the image name earlier when I erase the switch intentionally I copied back the same image so therefore I don't have to change this but let's say you buy a switch off ebay and it's been sanitized and you expose them a new image to it you may have to change this to another image name in order to do this you just use the set boot keep in mind boot is case-sensitive and the image name bib and after that you can just type in the boot command or if you don't want to change it in rom monitor mode you can use the boot flash and image name been this way and when you boot into iOS you can change it from there as well since I don't have to change this I'm just going to go ahead and type boat and as you can see the switch automatically extracts the image and loads it into memory and base the image well I hope this video has been helpful for you and I definitely like to thank you for viewing

Channel: Lextraindotcom

Views: 195,822

Keywords: Cisco, IOS, Image, Recovery, xmodem, Catalyst, Switch, 2950, 3550, 3560, 3750

Id: zxTO5qxti-I

Length: 9min 21sec (561 seconds)

Published: Fri Jan 09 2009