Cisco constantly releasing new versions of the Cisco iOS, which include new features as well as resolve
issues such as bugs in the iOS.
In this video, we'll look at upgrading Cisco iOS images
the high-level steps are that you firstly need to select and download the correct iOS image for your
router.
You then need to verify connectivity to your TFTP server where you've downloaded and stored the new iOS
image.
You should verify that your router has sufficient flash memory space for the new iOS image, and then you
copy the iOS file from the TFTP server to the router, you then configure the router to boot using the
new Cisco iOS image and then lastly, reload the router so that it reboots and loads the new iOS image
into memory.
In this example, I've got an 1841 router, so show version shows me the platform.
We are running currently the Cisco iOS 1841 software
so this is the current release and version of software that we're running.
This is the boot ROM operating system version
and once again, this is a Cisco 1841 router. So on the Cisco website, I've gone to support and downloads
and I'm going to select 1841 Integrated Services Router.
I'm going to select software on Chassis
and in this example, I'm going to look at Cisco IOS images rather than ROM monitor or other operating
systems
and what you need to do now is download the relevant version of iOS.
Now it's important that the D RAM and Flash B large enough for the operating system that you're
downloading.
This router has this amount of memory, so you need to add those two together.
So that's this amount plus this amount
which gives us about 130 meg of RAM.
We've got about 62 meg of flash, so my router would not be able to use this version of operating system
because the RAM and Flash requirements are greater than what this router currently has installed.
So very importantly, make sure that your router can support both the DRAM and flash requirements
of any new operating system that you download from Cisco.
So click on the download link to download the operating system, you need to login and make sure that
you have a service contract.
So do that and then download the operating system to your local PC.
In my example, I'm going to use this operating system, which I've already downloaded.
You're going to want to make sure that your router has enough Flash space for the new image that you're
downloading. So use the command show flash to ensure that the amount of available space is enough for
the image that you want to copy to flash. On my example, I've already copied this image.
The image is only 15 meg in size and I have enough space in Flash to copy another version of this image
or a different image into the flash of the router.
At the moment, this router is using this operating system
12.4-2.T4 that can be seen in the Flash of the router, so this is the image that's being used.
Let's pretend that we are going to upgrade the router to a newer version, even though it's the
same.
I'll show you the full process.
So what you would do is download the relevant operating system from Cisco and put it in your TFTP servers
directory.
In this example, I'm using solarwinds and this is the directory that the TFTP server is pointing to.
So you would type copy in this example, TFTP
Flash
press enter.
What is the IP address of the TFTP server?
So in my example, it's 192.168.1.199.
What is the source file that we want to copy?
So that file make sure that you put the bin extension in the file name.
What is the destination file name in this example?
I'll make it file 2.
We are warned that that file already exists.
Do we want to override it? And in this example, I'm going to override it so that file will be overridden
with this new file that's copied down from the TFTP server.
So we can see some messages on the TFTP servers stating that the file has been fetched, so there's a get
message.
We can see the file being copied down to the router from the TFTP server.
That'll take a while and the length of time depends on how large the iOS file is and what kind of connection
you've got between the TFTP server and the router.
If you're doing this across a WAN or wide area network, as an example, it could take a lot longer.
Now, in that example, there was a problem where part of the file wasn't successfully copied, but
here it won't be a problem, even though we're using TFTP because the TFTP protocol has retransmissions
and checks of files received.
So even though user datagram protocol or UDP is being used, the TFTP protocol ensures that the full file
is copied
and we can see that we had a check of the file that succeeded so the file was copied successfully.
So once again, in Flash, this is the file that we've copied down and now we can tell the router to
boot the system from the flash and the file that we're going to use is this new file.
So I've added that command to the running-config once again at the moment, it's not using that file,
it's using this file
so T4.bin
but we have now told the router to use T4_2 so it's a different file to the original file
that the router is using.
So I'll save the configuration and then I'll reload the roster.
So when the router boots now it will use this new file rather than the previous file as the operating
system that's loaded into memory.
I'll speed up the boot process in the video to save you the time of watching the router boot up.
OK, so router is booted up, I'll press enter to continue,
put in my relevant password,
show version,
shows us now that it's using the T4_2.bin file, so it's now using the new operating system
that we downloaded from the TFTP server.
It's not using the original file that we had in flash,
it's using this file rather than this file.