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So, now it's time to talk about the access layer.

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The access layer's job is to connect our endpoints.

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Our users have laptops and tablets and PCs and phones and all kinds of things

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that need

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to be connected to the network and they come in on the access layer.

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This means that once again we're going to care about port count.

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But things get a little bit more interesting than just talking about port count

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on a pair

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of switches like at the core layer, the distribution layer.
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of switches like at the core layer, the distribution layer.

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Because once again the biggest difference with the access layer versus all of

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the other

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layers is we're going to have many switches.

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And typically these switches are going to be organized into access closets.

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So if we walk around a building we're going to find that there are closets

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where they

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have racks built in and we might have two, three, four switches in there.

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We might have as many as eight or nine switches in there.

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Or more if we have a really dense environment.

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And so we have to consider for example, do we deploy 24 port switches?
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And so we have to consider for example, do we deploy 24 port switches?

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Do we deploy 48 port switches?

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And for that matter are we going to deploy things like one gig, base T, or are

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we going

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to go with multi gig switches.

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Multi gig switches support two and a half gig and five gig and even though most

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of our

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laptops and PCs don't need to and a half gig or five gig, guess what does we

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might want

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to deploy access points that want to take advantage of multi gig capabilities.
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to deploy access points that want to take advantage of multi gig capabilities.

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And so there's a lot to talk about when it comes to access layer features, but

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just starting

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with our basic port type and port count count conversation, which as we've said

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is happened

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at every single layer so far.

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Well now we're introducing a new level of conversation when it comes to the

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access switches.

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Now when we talk about the features that are required for our access layer,
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Now when we talk about the features that are required for our access layer,

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they're definitely

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going to be different than core and distribution.

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For example, we mentioned earlier power over ethernet.

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Well, power over ethernet isn't required at core and distribution layer because

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we're

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not connecting access points or phones at those layers.

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We're absolutely going to connect phones to our access layer.

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We're going to connect access points here and there could be all kinds of other

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devices

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that require it.

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For example, we might find that we're connecting cameras.
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For example, we might find that we're connecting cameras.

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These could be security cameras.

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We could have lighting these days that leverages power over ethernet and there

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are all kinds

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of other systems that are going to take advantage of P O E. They're all going

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to come in at

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the access layer and so we need to make sure number one that we support the

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proper P O E

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type.

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For example, do we need 30 watt or 60 watt or even 90 watt capabilities.

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But then we also need the proper P O E budget.

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This feels a little bit like the bandwidth versus packets per second
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This feels a little bit like the bandwidth versus packets per second

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conversation.

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It's great to be able to have the proper amount of bandwidth but we have to

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handle all that

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bandwidth on the back plane.

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Well, P O E is the same way.

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I could have 90 watts supported on every single port but can I actually support

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90 watts

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of power draw on every port.

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Now the good news is that very rarely do we actually need that.

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The bad news is we might completely still under spec the power budget.

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So let's keep that in mind when we're speccing out our access layer switches.
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So let's keep that in mind when we're speccing out our access layer switches.

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The next thing we need to worry about is edge configurations.

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So we're going to add configurations in here as well.

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We need to worry about VLAN assignment.

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This is typically via access port type of configuration.

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We might have trunks going out to devices.

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For the most part we don't see that even to access points these days.

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So for the usually we're talking about again access port assignment and the tr
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So for the usually we're talking about again access port assignment and the tr

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unks would

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exist upstream to the distribution switch.

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But it's not just VLANs that we have to assign as traffic comes in.

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A big part of the access layer configuration is going to involve QOS marking

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which can also

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be known as tagging.

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When a switch an access layer switch receives a packet from a host we are going
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When a switch an access layer switch receives a packet from a host we are going

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to have to

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send that packet upstream to the distribution layer.

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Well, the distribution layer is going to have policies for how to process that

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traffic.

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And so we need to tell the distribution switch what type of traffic this is.

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Well the two ways we do that primarily are going to be with a VLAN ID and with

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a QOS tag.

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And so this is an important part of what's happening at the edge of our network

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.
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The access layer sort of our first point of entry and it's the first

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opportunity for

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us to identify the traffic type.

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Now as part of QOS we also have the concept of the trust boundary.

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I need to decide do I trust the device that's sending me QOS marked frames.

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If for example this is a laptop then I'm probably not going to trust it.

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But if it's an IP phone well then I probably do want to trust it.
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But if it's an IP phone well then I probably do want to trust it.

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And so this is what we call establishing the trust boundary.

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There we go.

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Establishing the trust boundary at the edge of my network.

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And so QOS is definitely a topic of conversation throughout this course.

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It's going to be but also we need to make sure we understand that the initial

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marking,

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tagging and trust boundary configuration all happens at the access layer not at

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the

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distribution or the core layers.

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And then lastly we do have some amount of access control here as well.
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And then lastly we do have some amount of access control here as well.

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Now at this point we're concerned about whether the device deserves or should

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be on the

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network at all.

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Not just whether they can access certain resources.

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Remember the access control between resources exists at distribution layer.

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Here we're talking about should they have any amount of network access.

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And so we're going to use maybe a protocol like 802.1x which is an
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And so we're going to use maybe a protocol like 802.1x which is an

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authentication mechanism

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that allows us to control whether somebody gets online or not.

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The other way we can do this is with port security which simply uses MAC

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addresses to filter

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out whether devices are allowed on the network.

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So whether we're talking about hardware features like POE or configurations

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like VLAN and QOS

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marking and assignment either way the access layer does have some of these

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features and configurations

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that are required that actually belong here at the network edge rather than at
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that are required that actually belong here at the network edge rather than at

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the core

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or distribution layers.