We spent a lot of time in the last lesson
talking about the different physical and logical topologies.
Now, all of those logical ones
are still going to apply to our wireless networks,
but when we talk about it from a physical perspective,
wireless does add two different modes
that we need to understand.
So when we look at the first one,
this is called infrastructure mode.
Infrastructure mode is the most common type
of wireless network.
In fact, it's probably the one you're using
to watch this video.
If you're sitting at home, you have wireless in your house
and it connects to an outside provider
through your cable or your fiber modem,
this is infrastructure mode.
You have a centrally managed device,
your wireless access point,
and that you've given it a name, probably a password,
and you use that as you would a star topology
in a physical network, but you're doing it wirelessly.
Now, this is going to support wireless security controls
and other benefits that you just don't get
when you go to our second mode, which is known as ad hoc.
Now, ad hoc is decentralized.
It operates like a peer-to-peer network does.
There's no routers, there's no access points.
Instead, I connect my laptop to your laptop,
and we can make those routing decisions on the fly
and make them dynamically.
This can allow people to jump in
and jump out of the network as much as they want.
It's almost like the old school chat rooms we used to have
on AOL or CompuServe, right?
People would come in, they'd talk, and then they'd leave
and they would just come in and out all of the time.
Well, that's how this wireless network would work
when you're dealing with ad hoc mode.
Now, there is a third type that we have,
which is called a wireless mesh,
and you might think, oh, well,
that's just going to be a combination of the other two.
Well, not really.
A wireless mesh is actually completely different.
A wireless mesh is an interconnection
of different types of nodes, devices, and radios
to create this mesh topology.
So if we're going to have different routers
and gateways and clients and servers and radio antennas,
we're going to mesh them all together
and create this unique network.
So we can use different radio frequencies
like Bluetooth and Wi-Fi, and microwave and cellular
and satellite, and all of them can combine
into this single wireless network
so that we can expand our network access.
This gives us redundant and reliable connections
as we move forward, especially in harsh environments.
So where might we use a wireless mesh topology?
Well, after there's a hurricane
or another disaster-related event, people may come in
to do humanitarian assistance in the area,
and when they come,
they're going to bring their networks with them
because they need a way to communicate back
to where they came from.
So some of them will communicate over cellular
if the cellular network still works,
some over wireless that they bring in and set up,
some over satellite, some over microwave,
some over a landline.
But even if you had a landline, it may not be reliable
because there was a disaster there,
and so they might back that up using a wireless signal
or a satellite or a cellular modem.
Now as we have
all these different connections working together,
this gives us our mesh topology.
So maybe we set up a basecamp that has Wi-Fi in it
for everybody to access,
but then we have it connecting to another base camp
over a microwave link,
and then we have that connecting back over satellite
back to their home country.
This is the idea of using this wireless mesh network.
We're combining these two or three or four
different technologies to create a mesh network
that can be used by anyone.
Now, as we keep expanding our networks over a large area
by combining things with microwave and satellite
and cellular, this is going to allow us
to be able to have all the stuff working together well,
because we have wifi,
that can only go maybe a hundred or 200 feet, right?
But a microwave link can go 30 or 40 miles,
and satellite can go hundreds or thousands of miles.
And so this is the idea here.
As we create this mesh, we can keep expanding our access.
As you can see here in the diagram
where I'm going to be using satellite
to go for thousands of miles,
microwaves to go tens of miles,
and then wireless, which goes, you know,
maybe tens of feet or hundreds of feet.
And we can pull all of this together
to create this great, reliable,
redundant network that we can use
during a disaster or humanitarian assistance type mission.
That's the idea.
So as we talk about topology specific to wireless,
I want you to remember the three types,
infrastructure, ad hoc and mesh topology.