Alright, here's our challenge scenario.
We have a network here and we've got some wireless LAN controllers, a couple of
layer
two switches, and then this layer three device here in the middle, creating
layer three segmentation
among some of the wireless LAN controllers that otherwise would just have layer
two connections
because these layer two switches are just going to carry VLAN straight across.
So the scenario is that we are this person down here at the bottom.
We've got a mobile device and we're going to take a stroll. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We've got a mobile device and we're going to take a stroll.
We're going to walk from one end of the network to the other, physically, and
we're going
to start on access point one here, and then we're going to roam to access point
two and
from there, roam to access point three and so on and so forth.
And so what I want to have us do from a challenge perspective is, first of all,
we're going
to identify the roaming type.
We talked about those three different roaming types in the lightweight
architecture.
So let's go ahead and start with that. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So let's go ahead and start with that.
Second of all, we want to identify whether there's an anchor controller
involved with
this specific roam.
And finally, what I'd like to do is identify where the point of presence is for
our device.
So if our device sends a wireless packet into the network, where does the
network first
see it show up?
Now, just to be clear, once again, we have layer three device in the middle.
These are layer two switches, and all of these here are representing our capweb WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
These are layer two switches, and all of these here are representing our capweb
tunnels.
So go ahead and pause the video, take a moment to answer these three questions
on a per-roam
basis.
For example, as I roamed from access point one to access point two, what is the
roaming
type?
Do we need an anchor controller?
And what is the point of presence?
Namely, which switch do I first show up on?
All right, so hopefully that was enough time for you to hit the pause button
and answer
these questions.
It's a great exercise for helping us to identify what exactly is happening here WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
It's a great exercise for helping us to identify what exactly is happening here
with our wireless
network.
So let's go ahead and start with moving from access point one to access point
two.
As we see, this is staying within the same wireless LAN controller.
So this is going to be known as that intra layer two roam.
intra controller means that it's within the same controller, and if it's within
the same
controller, it's always going to be layer two.
So we don't need an anchor controller, because generally speaking, we're only
going to need
one if it's a layer three roam, and our point of presence is going to be right WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
one if it's a layer three roam, and our point of presence is going to be right
here.
We're going to be showing up on this interface on this switch when we get to
access point
two.
So next we roam to access point three here.
We are now on access point three, which is on this wireless LAN controller.
So we went for we're going from this WLC to this WLC down here, and now check
it out.
We are going across this layer three boundary.
We're going from this wireless LAN controller down to here. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We're going from this wireless LAN controller down to here.
So in this scenario, we are going to have this be an inter, meaning we're
between two
different wireless LAN controllers.
And then again, we're going across a layer three boundary.
So this is inter layer three.
So that's the roaming type.
We do need an anchor.
Absolutely, we're going to need an anchor controller for this roam, because it
's layer
three.
And lastly, our point of presence is actually believe it or not the exact same.
So this is what might trick us up a little bit with this scenario. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So this is what might trick us up a little bit with this scenario.
Remember, the use of the anchor controllers to say this is my anchor.
And as I roam across, let's do it like this.
But I roam to access point three here, now, yes, I'm attached to access point
three, but
as traffic comes in from a layer three perspective, it's going to get routed
towards where that
subnet lives, which is where the anchor controller lives.
And so even though there's communication back and forth here, my packet is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so even though there's communication back and forth here, my packet is
going to go to
the anchor controller and then show up on that switch up there.
So clean up our diagram, just a little bit here, but do understand that the
point of
presence is once again, in the same location.
Now next, we're going to roam from a one wireless lane controller here to this
wireless
lane controller.
Now I will say this, given the use of anchor controllers and all of these
things, we're
kind of treating each one of these as a separate scenario. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
kind of treating each one of these as a separate scenario.
So if we're migrating, if we're roaming from one foreign controller to another,
the anchor
controller is actually going to stay that whole time.
And so this creates an interesting situation.
So let's just go ahead and evaluate this one step at a time.
So we are going to make this an inter controller roam.
However, there's only a layer two boundary in the path here.
There's no layer three boundary.
So this is inter layer two.
This means that I can stay on the same subnet.
But again, this was a foreign controller, which just means that this is going WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But again, this was a foreign controller, which just means that this is going
to be my
new foreign controller.
And I'm going to keep the anchor controller in place.
So if that was your answer to say that, hey, my point of presence stays where
the anchor
is, then that's actually a perfectly viable solution in this situation.
If however, we took this as saying, hey, I'm going to start over, let's say
that now
I'm just using this as my initial wireless lane controller.
And now I'm migrating over to this wireless lane controller, while an inter WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And now I'm migrating over to this wireless lane controller, while an inter
layer two
isn't going to use an anchor.
And it is going to make it so that my point of presence now belongs with the
new wireless
lane controller.
So either one of these would work depending on whether you felt like you're
starting over
or whether we were going to continue to use that anchor controller.
And lastly, we're going to see something similar here as we migrate to access
point five.
We're going back across that layer three boundary, which means that it is inter
, meaning multiple
wireless lane controllers, and it's layer three, meaning we will need an anchor WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
wireless lane controllers, and it's layer three, meaning we will need an anchor
controller.
And our point of presence is going to be wherever the, whoops, it's a really
wrong spot, wherever
the anchor controller is.
So if this is our anchor controller in this situation, then it would be there.
If we're continuing to pass around the foreign controller, then it gets
interesting because
we're going back to the scenario up here.
But as we see, it's a pretty fascinating conversation to unpack this
architecture because we do
have to track which type of room we're talking about and also, hey, as I roam WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
have to track which type of room we're talking about and also, hey, as I roam
from access
point to access point, my station might be bouncing around from one wireless
lane controller
to another.
And a lot of our networks for the most part will largely see most of our APs be
part of
a set of wireless lane controllers that are in the same location.
And that would largely be intra and inter layer two rooms.
But in the real world, we might have a situation again, campus.
I walked to an adjacent building.
It might have different subnets. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
It might have different subnets.
It might be part of a different wireless lane controller, whatever the
situation.
Now we're going to potentially use that anchor concept.
And always remember as well that the anchor concept can be used intentionally,
especially
for guest traffic forming a guest anchor controller that goes into the DMZ.
I hope this has been informative for you and I'd like to thank you for viewing. www.technet24.ir