So, now it's time to talk about the access layer.
The access layer's job is to connect our endpoints.
Our users have laptops and tablets and PCs and phones and all kinds of things
that need
to be connected to the network and they come in on the access layer.
This means that once again we're going to care about port count.
But things get a little bit more interesting than just talking about port count
on a pair
of switches like at the core layer, the distribution layer. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
of switches like at the core layer, the distribution layer.
Because once again the biggest difference with the access layer versus all of
the other
layers is we're going to have many switches.
And typically these switches are going to be organized into access closets.
So if we walk around a building we're going to find that there are closets
where they
have racks built in and we might have two, three, four switches in there.
We might have as many as eight or nine switches in there.
Or more if we have a really dense environment.
And so we have to consider for example, do we deploy 24 port switches? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so we have to consider for example, do we deploy 24 port switches?
Do we deploy 48 port switches?
And for that matter are we going to deploy things like one gig, base T, or are
we going
to go with multi gig switches.
Multi gig switches support two and a half gig and five gig and even though most
of our
laptops and PCs don't need to and a half gig or five gig, guess what does we
might want
to deploy access points that want to take advantage of multi gig capabilities. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
to deploy access points that want to take advantage of multi gig capabilities.
And so there's a lot to talk about when it comes to access layer features, but
just starting
with our basic port type and port count count conversation, which as we've said
is happened
at every single layer so far.
Well now we're introducing a new level of conversation when it comes to the
access switches.
Now when we talk about the features that are required for our access layer, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Now when we talk about the features that are required for our access layer,
they're definitely
going to be different than core and distribution.
For example, we mentioned earlier power over ethernet.
Well, power over ethernet isn't required at core and distribution layer because
we're
not connecting access points or phones at those layers.
We're absolutely going to connect phones to our access layer.
We're going to connect access points here and there could be all kinds of other
devices
that require it.
For example, we might find that we're connecting cameras. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
For example, we might find that we're connecting cameras.
These could be security cameras.
We could have lighting these days that leverages power over ethernet and there
are all kinds
of other systems that are going to take advantage of P O E. They're all going
to come in at
the access layer and so we need to make sure number one that we support the
proper P O E
type.
For example, do we need 30 watt or 60 watt or even 90 watt capabilities.
But then we also need the proper P O E budget.
This feels a little bit like the bandwidth versus packets per second WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
This feels a little bit like the bandwidth versus packets per second
conversation.
It's great to be able to have the proper amount of bandwidth but we have to
handle all that
bandwidth on the back plane.
Well, P O E is the same way.
I could have 90 watts supported on every single port but can I actually support
90 watts
of power draw on every port.
Now the good news is that very rarely do we actually need that.
The bad news is we might completely still under spec the power budget.
So let's keep that in mind when we're speccing out our access layer switches. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So let's keep that in mind when we're speccing out our access layer switches.
The next thing we need to worry about is edge configurations.
So we're going to add configurations in here as well.
We need to worry about VLAN assignment.
This is typically via access port type of configuration.
We might have trunks going out to devices.
For the most part we don't see that even to access points these days.
So for the usually we're talking about again access port assignment and the tr WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So for the usually we're talking about again access port assignment and the tr
unks would
exist upstream to the distribution switch.
But it's not just VLANs that we have to assign as traffic comes in.
A big part of the access layer configuration is going to involve QOS marking
which can also
be known as tagging.
When a switch an access layer switch receives a packet from a host we are going WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
When a switch an access layer switch receives a packet from a host we are going
to have to
send that packet upstream to the distribution layer.
Well, the distribution layer is going to have policies for how to process that
traffic.
And so we need to tell the distribution switch what type of traffic this is.
Well the two ways we do that primarily are going to be with a VLAN ID and with
a QOS tag.
And so this is an important part of what's happening at the edge of our network
. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
The access layer sort of our first point of entry and it's the first
opportunity for
us to identify the traffic type.
Now as part of QOS we also have the concept of the trust boundary.
I need to decide do I trust the device that's sending me QOS marked frames.
If for example this is a laptop then I'm probably not going to trust it.
But if it's an IP phone well then I probably do want to trust it. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But if it's an IP phone well then I probably do want to trust it.
And so this is what we call establishing the trust boundary.
There we go.
Establishing the trust boundary at the edge of my network.
And so QOS is definitely a topic of conversation throughout this course.
It's going to be but also we need to make sure we understand that the initial
marking,
tagging and trust boundary configuration all happens at the access layer not at
the
distribution or the core layers.
And then lastly we do have some amount of access control here as well. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And then lastly we do have some amount of access control here as well.
Now at this point we're concerned about whether the device deserves or should
be on the
network at all.
Not just whether they can access certain resources.
Remember the access control between resources exists at distribution layer.
Here we're talking about should they have any amount of network access.
And so we're going to use maybe a protocol like 802.1x which is an WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so we're going to use maybe a protocol like 802.1x which is an
authentication mechanism
that allows us to control whether somebody gets online or not.
The other way we can do this is with port security which simply uses MAC
addresses to filter
out whether devices are allowed on the network.
So whether we're talking about hardware features like POE or configurations
like VLAN and QOS
marking and assignment either way the access layer does have some of these
features and configurations
that are required that actually belong here at the network edge rather than at WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
that are required that actually belong here at the network edge rather than at
the core
or distribution layers.