All language subtitles for Free-CCNA-LAN-Architectures-Day-52-CCNA-200-301-Complete-Course_en

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In this video we’ll look at LAN architectures.

By architectures, I mean how devices like\n

These LAN architectures are exam topics 1.2.a,\n

The other topics in 1.2, 1.2.d which is WAN\n

will be covered in separate videos.

Here’s what we’ll cover in this video.

Actually, it’s exactly the exam topics I\njust pointed out.

First we’ll cover 2-tier and 3-tier LAN\narchitectures.

These are common traditional LAN designs used\n

Then we’ll cover spine-leaf architecture,\n

Finally I’ll briefly cover SOHO, Small Office/Home\n

Small networks like this are different than\n

network device acting as router, switch, firewall,\n

Watch until the end of the video for a bonus\n

ExSim for CCNA, my recommended practice exams\nfor the CCNA.

Before actually getting into the topics for\n

You have studied various network technologies\n

and switching, STP, EtherChannel, OSPF, FHRPs,\n

So, now let’s look at some basic concepts\n

Network design is a very deep topic and to\n

architect, requires a deep understanding of\n

Although there are standard best practices\n

The answer to most general questions about\n

the requirements of each network are different.

Now, in the early stages of your networking\n

That’s usually left for the more experienced\nengineers.

However, to understand the networks you will\n

important to know some basics of network design\n

So, in this video and the next few we’ll\n

And now, before introducing the two-tier and\n

topics of this video, I want to briefly introduce\n

and which I might use throughout this video.

These are general terms, not only for LAN\n

The first one is called a ‘star’ topology.

When several devices all connect to one central\n

below, so this is often called a star topology.

In the diagram below, all PCs connect to one\n

a star shape around the switch.

Note that in network diagrams the devices\n

But if many devices are all connected to one\n

regardless of how the diagram is drawn.

The next term is full mesh, which is when\n

6 routers, and each router is connected to\neach other router.

This is called a full mesh topology.

The last one I want to introduce is partial\n

Here’s an example with four switches.

Notice that the top two switches are both\n

two switches are not directly connected.

This is a partial mesh topology.

Okay, those are the three general terms I\nwanted to introduce.

You’ll see examples of them throughout this\n

Now let’s get into the basics of campus\nLAN design.

By campus LAN, I mean a LAN of devices in\n

Remember, LAN stands for Local Area Network.

First we’ll look at the two-tier LAN design,\n

the access layer and the distribution layer.

The two tier design is also called a ‘collapsed\n

is found in the three tier design, the core\nlayer.

Or more accurately, it combines the two together\ninto one layer.

So, in the next slide I’ll show you an example\n

This is the layer that end hosts connect to,\n

They will usually connect to an access layer\nswitch.

So, typically access layer switches have lots\n

QoS marking is typically done here.

This is the layer that end hosts connect to,\n

a good practice to mark traffic as early as\n

Security services like port security, DAI,\n

Also, switchports might be PoE, Power over\n

points or IP phones in the LAN.

So that’s the access layer, the switches\n

Then there is the distribution layer.

These switches aggregate connections from\n

So, depending on how many end hosts there\n

Those connections are then usually aggregated\n

switches, as you’ll see in the next slide.

Typically, this is the border between Layer\n

So, the distribution layer switches run both\n

protocols such as spanning tree.

This is not always the case, but usually the\n

to the distribution layer switches are Layer\n

SVIs on the distribution layer switches as\n

The distribution layer is used to connect\n

Okay, let’s look at an example.

Here’s a simple two-tier campus LAN network.

The two access-layer switches, A1 and A2,\n

and each also has a wireless access point\nconnected too.

D1 and D2 are the distribution layer switches,\n

This provides redundancy, by having extra\n

However, the connections between the access\n

So, spanning-tree protocol disables a few\n

Now, D1 and D2 are multilayer switches, and\n

So, they will probably be using a first hop\n

provide a redundant virtual IP address for\n

As I said before, the distribution layer is\n

or the WAN, as well as other parts of the\nLAN.

So, here’s the connection to the Internet,\n

And perhaps there’s another set of distribution\n

servers connected to the access layer switches.

Notice that each distribution layer switch\n

By the way, in a collapsed core two-tier design\n

called the core-distribution layer, because\n

These connections between distribution switches\n

Routing information can be shared via OSPF,\nfor example.

So, this is an example of a two-tier network\narchitecture.

The end hosts connect to the access layer\n

The distribution layer switches aggregate\n

to services like the Internet and to other\nparts of the LAN.

Now let me relate this back to those common\n

Although I haven’t drawn the diagram like\n

all connecting to one central device, each\naccess switch.

So, these are four small star topologies.

If I put more end hosts on the diagram and\n

would look more like a star, but I think you\nget the point.

And here we have a couple partial mesh topologies\n

Notice that the distribution switches are\n

switch, but the access switches aren’t directly\nconnected.

So, these are two partial meshes.

And finally, between the four distribution\n

Each distribution switch is connected to each\n

You’ll see elements of full-mesh, partial-mesh,\n

designs, and often combinations of them sometimes\n

Now, if the network gets larger we might have\n

Do you see anything wrong with this?

In large LAN networks with many distribution\n

across a campus, the number of connections\n

This makes it much more difficult and complicated\n

So, to help scale large LAN networks you can\nadd a Core Layer.

By the way, Cisco recommends adding a Core\n

In this case there are 6, so we should add\na core layer.

Here’s how it looks with a core layer added.

Each distribution layer connects to the core\n

between the distribution layer switches.

These core layer switches are a pair of very\n

So let’s take a look at how the core layer\nworks now.

When we add a Core Layer we now have a three-tier\n

Let’s talk about that core layer.

It connections separate distribution layers\n

The focus of this layer is speed, you might\n

CPU-intensive operations such as security\n

etc should be avoided at this Layer.

We just want fast forwarding of packets, nothing\nextra.

And the connections are all Layer 3.

We definitely don’t want spanning tree at\nthe Core Layer.

The core layer should maintain connectivity\n

Because it’s the backbone of the LAN, redundancy\n

Let’s take a look at the previous topology\n

Here’s how the network might look with the\n

This time, the core switches connect to the\nInternet routers.

And if we have additional distribution and\n

As you know, they will also connect to the\ncore switches.

So, this is an example of a three-tier campus\nLAN.

For smaller LANs two tiers is sufficient,\n

Okay, let’s review those tiers once more\nand then move on.

Here are those attributes of each Layer again.

For the access layer, remember that it is\n

often performs services like QoS marking,\n

For the distribution layer, remember that\n

the access layer and serves as the border\n

In a two-tier design it connects to services\n

a three-tier network usually those connections\n

Notice I added an extra note saying that it\n

Remember that, as aggregation of connections\n

Finally, the core layer is used in large LANs\n

the focus is on speed, so we avoid operations\n

All connections here are Layer 3.

Okay, that’s all for the two- and three-tier\ncampus LAN designs.

Keep in mind what I said earlier, there are\n

Although these two- and three-tier LAN designs\n

in the real world there are countless variations\n

Let’s move on to the topic of Spine-Leaf\narchitecture.

This photo I’m showing you was taken in\n

you it is because spine-leaf architecture\n

Currently I work for a large data center provider,\n

So, what exactly is a data center?

Data centers are dedicated spaces or buildings\n

They typically contain halls of racks, like\n

devices are mounted onto the racks.

Traditional data center designs used a three-tier\n

This traditional design worked well when most\n

Well, if we look at this diagram, north-south\n

distribution, core, and then perhaps out to\n

distribution and access layers.

These other sections of the LAN are drawn\n

north-south when drawing the arrows in this\n

This is in contrast to east-west traffic,\n

servers in the same part of the network like\n

parts of the LAN or out to the Internet.

With the precedence of virtual servers, which\n

by the way, applications are often deployed\n

servers, which increases the amount of East-West\n

If you’re not sure what a virtual server\n

is, like I said I’ll cover it soon in another\nvideo.

Anyway, the point is that with this increase\n

architecture led to bottlenecks in bandwidth\n

latency depending on the path the traffic\ntakes.

To solve this, spine-leaf architecture, also\n

one of the designers, has become prominent\nin data centers.

Here’s what spine-leaf architecture looks\nlike.

It’s two-tier, but different than the traditional\n

There are spine switches and leaf switches,\n

Every leaf switch is connected to every spine\nswitch.

If you look at the diagram below, there are\n

has three uplinks, one to each spine switch.

Therefore, every spine switch is connected\n

However, leaf switches do not connect to other\n

Finally, end hosts, for example servers, only\n

They are like the ‘access layer’ of the\nspine-leaf architecture.

Okay, those are the main rules of spine-leaf\narchitecture.

The path taken by traffic is randomly chosen\n

And each server is separated by the same number\n

same leaf switch which have fewer hops of\n

for east-west traffic, traffic between the\nservers.

For example, for this server on the left to\n

And then to reach this other server it once\n

So, that’s spine-leaf architecture.

It’s also very simple to scale, because\n

add another leaf switch and connect it to\n

As with all topics in the CCNA, there is a\n

than what I just mentioned, but make sure\n

for the CCNA exam, and you should be set.

Now let’s move on to the final topic.

That final topic is SOHO networks.

Small Office/Home Office, also called SOHO\n

a small home office with few devices.

Now, it doesn’t actually have to be used\nas an office.

If your home has a network connected to the\n

SOHO networks don’t have complex needs,\n

provided by a single device which is often\n

There is no need for a dedicated device for\neach function.

This one device can serve as a router, connecting\n

Also a switch, as there are usually a few\n

Also there are usually simple firewall functions,\n

coming from the outside network, but to allow\n

It also serves as a wireless access point,\n

for example, to the network using WiFi.

Also in some cases it can serve as a modem\n

the modem is a separate device.

Here’s an example of a simple home router,\n

For very small networks, there’s no need\n

a device dedicated to switching, a device\n

This one device can do it all.

So, although an enterprise network would have\n

combines them all into one small device.

Now, throughout this course we are focusing\n

Very small companies or home offices don’t\n

to hire a dedicated network engineer.

So, they often just rent a wireless router\n

Here’s a review of what we covered in this\nvideo.

First, traditional 2-tier and 3-tier LAN architecture.

Make sure you know the three layers, access\n

Then I introduced spine-leaf architecture,\n

Again, make sure you know the basic rules\n

Finally we took a brief look at SOHO, Small\n

They are small networks that typically have\n

with routing, switching, security, and wireless\naccess.

As always, watch until the end of the quiz\n

ExSim for CCNA, my recommended practice exams\nfor the CCNA.

Okay, let’s go to quiz question 1.

Which Layer typically serves as the boundary\n

Pause the video now to select the best answer.

The answer is B, distribution.

Typically, the connections from access layer\n

The connections from distribution to core\nare Layer 3.

So, the distribution layer serves as the boundary\n

Which of the following would you NOT expect\n

Pause the video now to select the best answer.

Okay, the answer is B, STP, spanning tree\nprotocol.

Because the connections at the Core Layer\n

not be running in the core layer.

Okay, let’s go to question 3.

At which layer would you expect to find PoE-enabled\n

Pause the video now to select the best answer.

Devices that use PoE like wireless access\n

all connect to the access layer, so that’s\n

In a Spine-Leaf architecture, which of the\n

Pause the video now to select the best answer.

The answer is B, a leaf switch.

Endpoints like servers can connect to leaf\n

to all spine switches, but leaf switches should\n

Okay, let’s go to question 5.

Which of the following functions might be\n

Pause the video now to select the best answer.

Okay, the answer is F. A wireless router,\n

network device that can provide routing, switching,\n

This kind of device is often used in SOHO,\n

Okay, that’s all for the quiz.

Now let’s take a look at a bonus question\n

There are supplementary materials for this\nvideo.

There is a flashcard deck to use with the\nsoftware ‘Anki’.

There will also be a packet tracer practice\n

In this case, although we didn’t cover any\n

opportunity to demonstrate an important concept\n

spanning tree protocol and FHRPs such as HSRP.

That will be in the next video.

To get the free flashcards and lab files for\n

Before finishing today’s video I want to\n

To join, please click the ‘Join’ button\nunder the video.

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