When we think about the management of our wireless networks, things are a
little bit different
than when we're managing our switches and our routers, primarily because of the
sheer
number of access points.
We're talking about wireless communications.
We usually have an access point, which is our network device that maintains a
wired connection
to the switched infrastructure.
And then we're wirelessly communicating to devices that are referred to as
stations.
And abbreviated like so with STA capitalized. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And abbreviated like so with STA capitalized.
So sometimes I'll refer to these as clients as well, but either way we have
devices that
are wirelessly communicating to these access points.
And I know that back in the day when I was first just very young and entering
into the industry
I was responsible for largely just physical layer things like hanging access
points.
And eventually I learned how to do site surveys.
And I would go into a school and this is like in the mid 2000s and I could do a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And I would go into a school and this is like in the mid 2000s and I could do a
wireless
site survey and for the entirety of this building we just need to have six
access points.
And the reason for that was because six access points would get the job done.
We were using 2.4 gigahertz which could go a lot further.
We had lower client density and so we didn't need a lot of AAPs.
And so we might go into a school system and across many different schools maybe
in total
we had 50 or 60 access points.
So still a lot of AAPs but it was at least somewhat manageable to manage every WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So still a lot of AAPs but it was at least somewhat manageable to manage every
single AP on its
own.
But even 60 was a lot and as we've had to get into more modern applications and
modern
wireless devices we've seen the number of AAPs increased dramatically.
That same school system that maybe needed 60 access points today might need 300
or 600.
And so we needed a better way even in the mid 2000s and late 2000s to manage WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so we needed a better way even in the mid 2000s and late 2000s to manage
these access
points.
And that led to the creation of the lightweight architecture.
In a lot of ways lightweight wireless was sort of a first step into the world
of software
defined networking.
Because what we did was we said that the amount of intelligence that's required
on this
access point here could be lowered.
I didn't write that very well.
So let's try that again. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So let's try that again.
We could lower the intelligence level and ultimately the functions of the
software that's
running on this access point.
So it's a more lightweight software image which is where the name comes from.
And then we are connecting back to a wireless LAN controller.
This wireless LAN controller is responsible for maintaining the management of
that device.
And so we could have again lots and lots of access points all communicating WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so we could have again lots and lots of access points all communicating
back to the
wireless LAN controller.
And I don't have to manage each one of these access points individually, which
is what
I had to do before a lightweight came around back when it was what we refer to
as an autonomous
architecture.
So lightweight does a lot of good for us and a lot of times it's commonly
centered around
the idea of deploying wireless LAN controllers into our environment.
And this is a beautiful thing because if I were to deploy let's say another WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
access point
into the environment, it will automatically find the wireless LAN controller.
And there's a lot of ways that we can help it discover it.
We'll talk about that momentarily.
And the wireless LAN controller is going to push configuration down.
Furthermore, as these access points are nearby each other, we might have one
access point
on channel 40 in the 5 gigahertz space.
And therefore we wouldn't want this wireless or access point to be on channel WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And therefore we wouldn't want this wireless or access point to be on channel
40 instead.
The wireless LAN controller would say, all right, we're detecting channel 40 in
the area.
Maybe we're detecting a bunch of other channels.
We think you should deploy on channel 60.
And this might change over time.
But in the end, we're trying to dynamically manage a wireless environment that
isn't static.
Wireless needs change dramatically even within the course of a day.
The amount of interference and the amount of other wireless activities could
prompt us WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
prompt us
to change not only the channel, but also the transmit power level.
And so the wireless LAN controller is capable of monitoring the wireless
environment and adjusting
it on an as needed basis.
From a, again, management perspective, me as the admin, I don't have to go out
and manage
all of these access points.
Instead, I manage them all through one device.
That's the wireless LAN controller.
So what exactly is this wireless LAN controller? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So what exactly is this wireless LAN controller?
Well, for the most part, a wireless LAN controller is going to be a physical
device or appliance
that's going to live on the network somewhere.
And where it lives is very important.
And we'll talk about that later on.
Now they can also take different forms as well these days.
For example, we could deploy it as a virtual appliance.
And a virtual appliance just means that it has to live on one of my virtual WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And a virtual appliance just means that it has to live on one of my virtual
hosts inside
my data center.
We don't often want our wireless LAN controllers to live inside of our data
center.
And so we could deploy this on a virtual host that connects in at a
distribution layer somewhere.
But either way, we could deploy the Cisco makes it available.
First is download the software for a wireless LAN controller.
And rather than purchase an appliance that is a physical set of hardware like
CPU and memory
and all of these things, I can create my own server and deploy the software WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
and all of these things, I can create my own server and deploy the software
onto that.
So that's the concept of deploying it as a virtual appliance.
We can also deploy it into the cloud as a virtual appliance.
Now there's two different aspects to the cloud.
So first of all, I could deploy this concept here, but rather than deploying it
onto my own
physical host, I just deploy the virtual appliance into a cloud space known as
infrastructure
as a service. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
as a service.
It's basically me saying I'm going to spin up a virtual machine in the cloud
and run it
there.
And I could also run this as a controllerless environment.
The best example of this from a Cisco perspective would be Miraki.
Miraki is a product line that originally was a competitor to the Cisco.
Cisco acquired them quite a long time ago at this point.
And I connected an access point to my network and it goes out to the cloud and
just finds WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
just finds
the controller that exists out in Miraki's space.
So that means that I don't have to deploy anything here.
I have to deploy something myself here.
I don't have to deploy anything.
And either way, the controller and the management functions exist in a cloud
space.
So both of those might be something we'd consider.
Now the other thing is in smaller environments, we might even see this showing
up inside of
other devices.
For example, we could see this embedded either in switches. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
For example, we could see this embedded either in switches.
Cisco has switches that allow you to embed a wireless LAN controller in there.
And then we also have the ability to convert an access point into a very
lightweight type
of controller, which can be very useful for small locations.
I take a bunch of access points that are in an area.
I turn one of them into the wireless LAN controller from a functionality
perspective.
And that way I can manage this very small space without having to purchase a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And that way I can manage this very small space without having to purchase a
larger than
needed wireless LAN controller set of hardware.
And so this is known as the embedded wireless controller, EWC solution when we
're deploying
it onto an access point.
Now it's worth noting that Cisco actually had two different products and they
're trying
to migrate towards one of those.
So originally when I talk about the mid-2000s Cisco made an acquisition of a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So originally when I talk about the mid-2000s Cisco made an acquisition of a
company called
Airspace.
And previously they had acquired an access point company called Aeronet.
So quite a few different products here that they purchased.
And the funny thing about this is that this architecture existed for a very
long time.
It survived a couple of decades and probably even longer than that.
And when we look at these products together this is at this point considered to
be a legacy WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
be a legacy
product line.
If I were to go out and purchase for example a 5500 controller or an 8500
controller or
a 3500, these are the old Aero-S.
So running the operating system from Airspace, Aero-S as we called it.
Those are a more legacy product line.
And Cisco isn't actively selling these anymore.
And the configuration of these was quite different thanks to the underlying
operating system.
These days Cisco has an iOS Xe platform that they put underneath the catalyst WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
These days Cisco has an iOS Xe platform that they put underneath the catalyst
product umbrella.
Meaning that we used to refer to catalyst as just switches.
Nowadays it can apply to routers and it can apply to access points and it can
apply to
wireless LAN controllers.
For example they have the catalyst 9100 access point line and they have the
catalyst 9800 wireless
LAN controllers.
And if I want to configure these again they are running iOS Xe.
It feels a whole lot like I'm logged into a Cisco switch from a CLI perspective WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
It feels a whole lot like I'm logged into a Cisco switch from a CLI perspective
.
Whereas the CLI for these legacy products it required studying because it was
very different
than anything else that Cisco had.
Now we mentioned that when we come online the access points are automatically
able to discover
the wireless LAN controller.
So they perform this WLC discovery process.
They're going to start by performing a broadcast to find out if the wireless WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
They're going to start by performing a broadcast to find out if the wireless
LAN controller
is on the same subnet as me.
In larger networks this is rarely the case.
Usually the wireless LAN controller lives out in the middle of the network
somewhere and
we have access points all over the place on all kinds of different subnets.
So this is only going to work in lab environments in very small spaces.
The most common way that we perform discovery is via DHCP.
One of the cool things about migrating to a lightweight architecture back in
the day was
we were able to leverage DHCP for our access points. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
we were able to leverage DHCP for our access points.
When it was autonomous I had to manually configure all of these access points
while I needed
to track their IP addresses.
With lightweight I can perform DHCP and DHCP by default doesn't include
wireless LAN
controller information but it can provide lots of other information via options
.
So I can use DHCP option 43 which is a configuration on pretty much every DHCP
server these days. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
server these days.
I can tell that server hey you need to pass a particular IP address via this
option.
So when I receive the IP address I'm going to receive the IP address and the
gateway and
the subnet mask and all these things but I'll also receive a wireless LAN
controller IP address.
So that's the value of using DHCP and again it's the most common option in my
experience
for locating a wireless LAN controller that's remote.
Nesisco does give us a DNS option when we come online we'll get as part of DHCP WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Nesisco does give us a DNS option when we come online we'll get as part of DHCP
we're
also given DNS servers so if I don't get an IP address via this DHCP process I
can instead
get the DNS entry or the DNS server rather and then I can perform a name
resolution of
sysco capwapcontroller.local.
And so this is actually dot local dash domain.
So this is an option that we can use if we for whatever reason aren't able to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So this is an option that we can use if we for whatever reason aren't able to
use DHCP
option 43 then we can certainly perform this DNS look up.
And lastly we can actually perform this as a or perform a manual operation.
I can log into the access point I could console into it for example and I could
tell it
the IP address of the wireless LAN controller.
So regardless we have lots of options and lots of ways for our access points to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So regardless we have lots of options and lots of ways for our access points to
figure
out where in the network the wireless LAN controller is.
Now once an access point comes online and performs this discovery it's going to
maintain
a list of all of the wireless LAN controllers that it becomes aware of.
This way when it reloads it doesn't have to go through this discovery process
again it
can just immediately go out to its list of known controllers and if it can't
find a wireless
LAN controller maybe that WLC is down it can then perform this discovery WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
LAN controller maybe that WLC is down it can then perform this discovery
process again.
But ideally we only have to do this for initial discovery because for the most
part our wireless
LAN controller configurations are going to be relatively static and they're not
going
to be moving around.
Now we do have a lot of design considerations to make when it comes to our
wireless LAN
controllers and that's going to be the focus of this part of this course is to
be drilling
into the idea of how do we deploy a wireless architecture what is going to be WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
into the idea of how do we deploy a wireless architecture what is going to be
required from
a design perspective.
I've got to think about things such as licensing to make sure that I have
wireless LAN controllers
that are large enough and licensed enough for the number of access points in my
environment.
So I do need to consider the hardware sizing of my wireless LAN controllers.
We have small, medium, large wireless LAN controllers for example we've got to
consider failover
because if a wireless LAN controller goes down we don't want to lose access to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
because if a wireless LAN controller goes down we don't want to lose access to
our wireless
network.
They rely on the wireless LAN controller because the APs are lightweight and
they aren't functioning
fully on their own.
And lastly we mentioned it earlier we do need to worry about the wireless LAN
controller
location. This is a critical part of a wireless architecture design and we'll
talk about the
reasons for that here shortly.
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