-: We spent a lot of time in the last lesson, 2 2
talking about the different physical and logical topologies. 3 3
Now all of those logical ones 4 4
are still going to apply to our wireless networks. 5 5
But when we talk about it from a physical perspective, 6 6
wireless does add two different modes 7 7
that we need to understand. 8 8
So when we look at the first one, 9 9
this is called Infrastructure Mode. 10 10
Infrastructure Mode is the most common type 11 11
of wireless network. 12 12
In fact, it's probably the one you're using 13 13
to watch this video. 14 14
If you're sitting at home, you have wireless in your house 15 15
and it connects to an outside provider 16 16
through your cable or your fiber modem. 17 17
This is Infrastructure Mode. 18 18
You have a centrally managed device, 19 19
your wireless access point, 20 20
and that you've given it a name, probably a password. 21 21
And you use that as you would a star topology 22 22
in a physical network, but you're doing it wirelessly. 23 23
Now this is going to support wireless security controls 24 24
and other benefits that you just don't get 25 25
when you go to our second mode, which is known as Ad Hoc. 26 26
Now Ad Hoc is decentralized. 27 27
It operates like a peer-to-peer network does, 28 28
there's no routers, there's no access points. 29 29
Instead, I connect my laptop to your laptop 30 30
and we can make those routing decisions on the fly 31 31
and make them dynamically. 32 32
This can allow people to jump in and jump out 33 33
of the network as much as they want. 34 34
It's almost like the old school chat rooms 35 35
we used to have on AOL or CompuServe, right? 36 36
People would come in, they'd talk and then they'd leave. 37 37
And they would just come in and out all the time. 38 38
Well, that's how this wireless network would work 39 39
when you're dealing with Ad Hoc mode. 40 40
Now there is a third type that we have, 41 41
which is called a Wireless Mesh. 42 42
And you might think, oh, well, 43 43
that's just going to be a combination of the other two. 44 44
Well, not really. 45 45
A Wireless Mesh is actually completely different. 46 46
A Wireless Mesh is an interconnection of different types 47 47
of nodes, devices, and radios to create this mesh topology. 48 48
So if we're going to have different routers and gateways 49 49
and clients and servers and radio antennas, 50 50
we're going to mesh them all together 51 51
and create this unique network. 52 52
So we can use different radio frequencies 53 53
like Bluetooth and WiFi and microwave 54 54
and cellular and satellite. 55 55
And all of them can combine 56 56
into this single wireless network 57 57
so that we can expand our network access. 58 58
This gives us redundant and reliable connections 59 59
as we move forward, especially in harsh environments. 60 60
So where might we use a Wireless Mesh topology? 61 61
Well, after there's a hurricane 62 62
or another disaster related event, 63 63
people may come in to do humanitarian assistance 64 64
in the area. 65 65
And when they come, they're going to bring 66 66
their networks with them because they need a way 67 67
to communicate back to where they came from. 68 68
So some of them will communicate over cellular, 69 69
if the cellular network still works, 70 70
some over wireless that they bring in and set up, 71 71
some over satellite, some over microwave, 72 72
some over a landline. 73 73
But even if you had a landline, 74 74
it may not be reliable because there was a disaster there. 75 75
And so they might back that up using a wireless signal 76 76
or a satellite or a cellular modem. 77 77
Now, as we have all these different connections 78 78
working together, this gives us our mesh topology. 79 79
So maybe we set up a base camp that has WiFi in it 80 80
for everybody to access, 81 81
but then we have it connecting to another base camp 82 82
over a microwave link. 83 83
And then we have that connecting back over satellite, 84 84
back to their home country. 85 85
This is the idea of using this wireless mesh network. 86 86
We're combining these two or three or four 87 87
different technologies to create a mesh network 88 88
that can be used by anyone. 89 89
Now, as we keep expanding our networks over a large area, 90 90
by combining things with microwave 91 91
and satellite and cellular, 92 92
this is going to allow us to be able to have 93 93
all this stuff working together well. 94 94
Because if we have WiFi that can only go maybe 95 95
100 or 200 feet, right? 96 96
But a microwave link can go 30 or 40 miles 97 97
and satellite can go 100s or 1,000s of miles. 98 98
And so this is the idea here, as we create this mesh, 99 99
we can keep expanding our access. 100 100
As you can see here in the diagram 101 101
where we're going to be using satellite 102 102
to go for 1,000s of miles, microwaves to go 10s of miles 103 103
and then wireless, which goes, you know, 104 104
maybe 10s of feet or 100s of feet. 105 105
And we can pull all of this together to create this 106 106
great, reliable, redundant network that we can use 107 107
during a disaster or humanitarian assistance type mission. 108 108
That's the idea. 109 109
So as we talk about typologies specific to wireless, 110 110
I want you to remember the three types, 111 111
Infrastructure, Ad Hoc, and Mesh Topology.