- So before we get into the details
of downloading the software and pairing it up
with Cisco iOS images and everything else
that's involved with that I just want
to take a step back for a moment and talk
a little about GNS3 from the standpoint
of is it a simulator or is it an emulator
and what's the difference and quite frankly
why should I care what the difference is?
Now GNS3, even though it does have the word
simulator in it, graphical network simulator,
the word simulator's in there because it's really
simulating network topologies, it's allowing you
to build network topologies without the real hardware
and the real cables in front of you.
So that's where it's really simulating things.
But GNS3 itself is actually what we call an emulator.
Now what's the difference?
Well when we say that something is an emulator
that that means that that software is running
an actual network operating system.
It's actually running in this particular case,
the real Cisco iOS image or maybe the June OS image
or whatever other images your import into it.
What's the difference between that and a simulator?
Well a simulator is a program that was built
from scratch to sort of look and feel like the software
but it's not really the software.
For example, way back when you were first learning
about let's say Microsoft Windows,
let's take that as an example,
there's some soft route there that you can,
on a CD plug into your CD rom drive your DVD rom drive
of your laptop and it will bring up a window
that looks like Microsoft Windows and for tutorial purposes
it'll say okay move your mouse over here
and click on this button.
Move your mouse over here and click over here.
So it's a software that's built to look like windows
but it's very limited right?
Maybe it only allows you to hit start and run
or maybe it only allows you to click
this particular icon but all the various things
that Windows can do it can't do because a simulator
is not the real software.
So I'm sure you're familiar with a lot
of simulation platforms out there,
especially when you're studying for
your Cisco certification exams.
A lot of simulations out there but what's one
key component that they all have in common
that's kind of difficult?
They don't give you access to all the commands,
there's a lot of stuff that you can't do in simulators
because Cisco iOS is huge, it's massive,
it's hundreds of thousands of lines of code
and a simulator just can't come close to that.
But GNS3 is an emulator.
In other words, GNS3 provides the platform
where you import your actual Cisco iOS images,
real Cisco iOS that would run on a real router
and then GNS gives you a nice gooey,
a nice front end that runs those iOS images.
So actually whatever those iOS images support,
whatever commands, whatever debugs,
whatever show commands they support, you now get in GNS3.
It's not just a simple, very generic vanilla
simulation program it is actually emulating real Cisco iOS.
So that is why when you're using GNS3
you have to somehow have access to a Cisco iOS image
because it's going to require that.
So that's all I want to talk about
in this section about the difference
between a simulator and an emulator and hopefully
I've gotten across to you the idea that an emulator
is much more powerful, gives you a full set
of the features, it's the exact same thing
you are using the exact same software as you would use
in a real environment with real hardware.
So in the next section we're going to start
talking about considerations.
You know once you've got this opportunity
to select various iOS images, what are some
of the things you have to think about
because you want to make sure you select
the correct one and put it in GNS3
so everything works according to
your specifications and your needs.
And we'll talk about that in the next set of videos.