Original subtitles

Well, hi, guys.

Hey.

So in this lesson, we're going to learn some well-known network architectures and by well known, I

mean, you're going to already you've heard about them.

I hope.

I think maybe does matter because after this you will.

So networks, right?

These are all divided into two groups.

We've got peer to peer and we've got client server.

And this is according to networking principles and communication types of the devices on the network.

So we'll talk about peer to peer network architecture first.

So networks with this type of architecture, all computers have the same rights and structure.

There's no concept of a service unit or host at a workstation or terminal.

Each client on the network has its own hard disk, and users can easily access and communicate with

another other users resources whenever they want.

So in this context, terminals share the data or service like a file or printer or the internet, that

kind of thing.

That they want to make available to the other terminals themselves.

So in other words, all computers in the network can act as both clients and servers.

And these such networks are often used in homes and small businesses that don't really require any centralized

management.

Now there's the client server architecture.

But don't worry.

Because each computer on the network now has a different role.

So these roles can be client and server.

And in this architecture, the server computer is located.

Well, sometimes it just at the very center and is responsible for setting the use of files and resources

and the privileges of all the other users.

Now, in terms of hardware.

Well, it's way bigger and has superior features than the average client computer, right?

In fact, all of the client computers are connected to the server computer and can perform operations

in line with the authorizations given by the server.

And in addition to that, client computers can act independently of the server as well.

But check this out.

They would not be able to access or use any files or resources that this server does not provide and

approve.

All right, so what about internet access that we use on a daily basis, right?

Constantly, some of us.

What is it, though, is it the client server model?

Well, yes, it is.

So the web browser is the client makes web page requests and and a web server sends the requested web

page to the client.

So the client server architecture actually has two different structures in terms of its layout.

We've got two tier and three tier.

Right, so in the two tier model, the client can communicate directly with the server, as the name

suggests.

There are two layers in the architecture of the client and the server layer.

And the model may cause some security vulnerabilities, as well as some performance problems, because

web browsers and web servers.

Well, they'll work in this architecture and right, sometimes you might have heard that there might

be some problems connecting to the internet or what you get back from the internet.

That's why.

They use something called SSL or secure socket layer.

Right, so SSL is used here to avoid security problems.

So, for example, if the server is a database server, the client can retrieve information directly

from this database server.

Yes.

Now in the three tier architecture, there is an intermediate layer between the client and the server.

Now this layer is used to provide security and grant rights and privileges to clients.

So this layer receives all the requests from all the clients and then forwards them to the server after

authentication.

So in the client's request returns from the server, it's been transmitted first to the middle layer

and then to the client.

So here there are three layers the client application and server.

All right, so now let's have a look at the server types.

So we've got a file server, OK?

And it's used to share various folders on the server and perform operations such as who can use the

folders, the file types that can be created here, and whether or not people can read or write.

And these are called permissions.

But its main task is essentially file sharing, right?

That's why it's called a file server.

So apart from sharing, it will also provide central storage services to clients.

And we've got a database server.

So these are the servers that are created to provide database services so clients can use a variety

of SQL statements, depending on the authorization given over the database servers.

For example, there's a SQL server, MySQL or Oracle.

These are some of the most well known database servers.

Now there's another thing called the transaction server.

So the transactions here actually allows using SQL statements, just like in a database server.

But it's kind of different because it allows multiple SQL statements to be run on the server in batches.

So it basically works with all or nothing logic.

In other words, if one of the SQL statements encounters an error, the changes made by the running

ask you, well, statements are reversed.

So, for example, when transferring money between two accounts, there are two school statements deducting

from the account and adding to the other account.

If there's a problem with one of them, there's going to be a lot of money in the accounts.

So transaction servers avoid such problems and reflects results to the accounts.

If both SQL statements work.

Otherwise, it just cancels both of them.

Web server, so this is responsible for storing the Web pages on the internet and sending these pages

to the requesting users and making everybody happy with cat videos and things.

So moving right along, we've got a proxy server, so a proxy server is used during internet access,

the computer that will access the internet access is through the proxy server.

That's a heavily visited page is cached by the proxy server, increasing the access speed by sending

it to the web page from a cache of the requesting computer.

Now, in addition to all of that, it can prevent users from accessing the page by banning the pages

to be accessed, or it can send the requesting computer after cleaning the inappropriate parts of the

pages containing the inappropriate content.

So proxy servers can actually clean infected files automatically.

They also reduce the chances of spreading a virus or malicious program, as no one on the network has

direct access to the internet.

Right.

They're all done through proxy.

So let's take a look and see the types of networks classified geographically.

All right, so we've got a pan, which is a personal area network.

So the personal area network or pan, is a type of network that has been used in recent years, it covers

an average area of maybe 10 meters, but under ideal conditions it can actually reach up to 100 meters.

It's a type of network that's created by mobile devices.

So a pen can be used to connect mobile devices to each other, as well as to connect to the internet

or share the internet, you know?

So wired pans can also be set up by connecting to a computer with the device's USB or FireWire ports,

or even wirelessly using network technology such as IATA, Bluetooth, Wireless, Z-Wave, Zigbee,

these kinds of things.

A land or local area network?

Is it type of network created for the communication and sharing of resources of devices in a small geographical

areas, such as a home, school and office or workplace, whatever?

So the speed in the network can actually reach gigabit level?

Twisted pair of cables, coaxial cables and fiber optic cables.

These were all used when creating land.

There's also bus ring, star and mesh.

These are topologies.

And today, lands are usually formed as a star topology with twisted pair cables.

Now we've also got a man, but don't be confused because this is the metropolitan area network.

So it covers a larger area geographically than a typical land.

It's also known as a campus network, so it can be used on university campuses and very large workplaces.

Networks created by enterprises spread across the country are also included in this class.

It's in fact often used to interconnect lands using fiber optic cable and high capacity backbone technology.

So an example of this would be intranet if you've heard of intranet.

Now, while the backbone of a man application can be provided by using one or two cables, modems are

actually widely used today.

And then we've got our wide area network or when.

So this is a type of network that is created by local networks at very far distances, so geographically

it's larger than a land and a man.

It actually can be a country or worldwide network.

The Inter Network connection can be made with fiber optic cable or with the help of satellites.

And although different from lens router devices are used in these networks.

So the most well-known when you've probably heard of it, too, we call it the internet.

Then we come to VPNs.

Now this is a virtual private network.

And this is something that probably is in everybody's email box or advertisement portfolio because everybody's

getting ads for the newest VPN.

But I'll explain to you what it is.

It's the lowest cost when creation method.

Right.

Because it's a virtual network that's created to provide encrypted and secure access to the networks

within an organization over the internet.

And it basically works as if it's part of the network.

So the same can be done with leased lines, but VPN is very low cost and easy to configure because the

VPN is virtual.

Multiple VPN users can use the network at the same time, and since the traffic on the VPN has provided

over the internet, security measures such as encryption, data verification and authorization can also

be taken for security purposes.

So VPN is set up to provide a confidential and private information flow between neighboring networks,

even if the package go over the internet, you see, even if they are listened to thanks to the security

measures used, the person attacking the encrypted packets cannot make sense of the information that

they could harvest.

So that means that VPN is actually divided into two.

According to the purpose of its use.

So these are remote access VPNs and site to site VPNs.

So we'll talk about remote access VPNs, because these will allow the networks to join the roaming corporate

network from anywhere.

Right?

Remote Access VPN.

Or it can be used for different offices of companies to communicate with the center.

Now we've got site to site VPN.

Site to site VPN is used to enable different companies to communicate over VPN and to enable different

offices of the company to communicate with its center office.

So the difference between remote access VPN and site site VPN is there's a VPN server between two points

that perform the VPN operation.

What about can?

Yeah, there's a can it's called Controller Area Network.

So it's a serial network technology that was developed by Bosch in the mid-1980s for use in automotive

automation.

Although it was developed, especially in vehicles, it has found its use in many branches of the industry.

So its purpose is actually to make cars safer and to save fuel because they can also make them lighter

and quicker.

So Can is essentially a system for automobile systems that works on the principle that the electronic

elements in the vehicles will send data to a single central executive element over a serial path.

For example, it enables systems such as the ABS and the ACR that need to be answered in a really short

period of time to be managed from a single center.

Can eliminate the crowd cabling structure, thanks to the bus structure and twisted pair cable it uses.

Although bus is the most commonly used topology in the Khan network, structure star and ring topology

can also be used.

Now, don't get that confused with Cam as the abbreviation for a campus area network.

This naming refers to the network that universities create within themselves.

So let's talk about the sand.

It's also known as a storage area network.

So it's a type of network that emerged when the storage areas of the servers on the network started

to become insufficient.

Can you believe that too small?

So storage area networks are basically lands used for storing and transmitting large amounts of data.

It provides a fast and reliable connection with fiber optic cable, oftentimes between servers and storage

units.

A storage unit on the network does not belong just to one server, but maybe is even common property

of the entire network.

Although servers do their part as storage media, their capacity can be limited and bottlenecks can

occur when many people try to access the same information.

Therefore, many organizations use peripheral storage device such as tape units, raid disks and optical

storage systems.

He says devices play an active role in backing up data online and storing large amounts of information.

Now, as server sizes and heavy applications increase, the traditional storage strategies mentioned

above are also failing because these peripheral devices are pretty slow to access and and transparent

access to these storage devices may not even be possible for every user.

So sand storage area networks offer faster access to data and more options.

So storage networks can provide high speed direct fibre channel connectivity between each server storage

system, as well as a tape backup library.

So this means that the local network will no longer be used to move data in the backup and restore process.

You see how that would be improving performance for those services and users on the local network.

It's always moving up.

So thanks for hanging in there, guess what, we've got somewhere else to go in the next lesson.

So I'll see you then.