Original subtitles

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So what is the USA model and how does it work.

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Of course you recall when we talked about the USA model so why don't we take a closer look.

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Get into some of these details as you may recall the U.S. model consists of seven layers and the U.S.

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I model raw data starting from the very top layer is transferred to a layer below by adding some additional

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information about that layer in Each subsequent layer.

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Then when the data is transmitted to the other party the data is transmitted from bottom to top

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So data is transmitted according to this always a model as follows Layer 7 application the application

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layer is where users actually communicate with a computer.

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OK so it doesn't have a top layer so that means it's not possible to provide service to that layer.

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The way we do another layer even if you remove all network components network guards etc from your system

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you can still use a browser such as Google Chrome Firefox to browse local HDL documents.

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Yeah however if you do want to access a Web page via HDP your browser will contact the application layer

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and then respond to your request.

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Well your 6 presentation so layer in which the data to be sent is converted into a common format that

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can be understood by the computer receiving the data resides on layer 6.

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This way is actually a converter if you will and it provides encoding and translation functions it performs

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tasks such as data compression and encryption and it ensures that the data that's transmitted from the

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application lever system can be read by the application layer of the other party layer five session

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on setting it up using and ending the session between two computers is done in this layer.

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So when a computer is in communication with multiple computers at the same time it will allow the user

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to speak to the current computers when necessary.

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Therefore transport this layer segments and then reassemble as data into a data stream the services

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in this layer divide reassemble and then combine data from top tier applications into the same data

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stream so in this way in case of data loss it will be a lot easier to respond because the data will

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be smaller.

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It also assigns a sequence number to each part in order to ensure that any missing parts will be identified

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and then completed by the recipient and TTP as well as UDP protocols will work in this layer.

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Layer 3 network so Layer 3 manages device addressing monitors the location of devices on the network

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determines the best way to move data it's responsible for transmitting traffic between devices that

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are not connected locally.

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So this is the layer that will select the best way to achieve the targeted data and this process is

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called routing and the device that performs this process is called you guessed it router Layer 2 data

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link.

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So basically this layer will convert messages from the network layer into bits for the physical layer

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most of the data link layer occurs within the network car it identifies other computers on the network

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it determines who is currently using the cable performs the tasks of checking data from the physical

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connection for errors and switches devices according to their MAC addresses so this layer faulty packages

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are checked and then sent again layer one physical layer the physical layer or the lowest layer is the

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layer closest to the physical network environment it's one that sends and receives bits so it deals

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with how to convert ones and zeros to electrical light or radio signals both parties must agree on the

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same rules to ensure communication and then when the data is transmitted to the other party this time

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the process from the first layer to the seventh layer is performed in reverse order.