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When the end user sends data, that data will go through all seven layers of the OSI model. The data is broken up into smaller and smaller parts beginning at Layer 4 ( The Transport Layer ) until it's in the form of electric signals that can be sent across the physical media.
As the data flows down the OSI model, it's referred to by different terms. You really have to master these and watch for them on your exams. There are four different terms you need to know :
- At the Application, Presentation, and Session layers, data is simply called "data". (these three layers has nothing to do with the data breaking )
- At the Transport layer, data is placed into segments.
- At the Network layer, data is placed into packets.
- At the Data Link Layer, data is placed into frames.
- Finally, at the Physical layer, data takes the form of bits - and remember, it's all ones and zeros!!!
If I mention "segments", you should know I'm discussing the Transport layer of the OSI model without any other hints, because you might not get any other hints!!!!
As data flows down the OSI model, each layer adds a header that will be removed by the same layer on the other end of the session. These headers are layer-spedific in that the Network layer couldn't care less about the contents of any header except the Network layer on the other end of the session.
As an end user enters data for transmission to a remote host, the first six layers of the OSI model will add a layer-specific header that contains information to be read by the same layer of the OSI model at the remote location. Note that Layer 2, The Link layer, adds both a trailer and a header.
The combination of data and a layer-specific header is called a Protocol Data Unit(PDU). There's a PDU for each layer; that is, the combination of data and L7 header information is called an L7 PDU, the data and L6 header information is called an L6 PDU, and so forth.
After the data is successfully transmitted by the Physical layer to the remote location , the data begins to travel back up the mode. Each layer will remove the header added by its counterpart - that is, Layer 3 removes the L3 header and reads it, L4 removes the L4 header and reads it, and so forth.
The term same-layer interaction describes the process of a give OSI layer removing the header placed on the data by the same layer on the sending side. For example, the Application layer on the receiving end will remove only the header placed onto the data by the Application layer on the sending side, and so forth.
The term adjacent-layer interaction refers to the interaction between layers of the OSI model on the same host. That is, the Application layer interacts with the Presentation layer, the Presentation layer interacts with both the Application layer ( the one above it ) and the Session layer (the one below it ), and so forth.
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When the end user sends data, that data will go through all seven layers of the OSI model. The data is broken up into smaller and smaller parts beginning at Layer 4 ( The Transport Layer ) until it's in the form of electric signals that can be sent across the physical media.
As the data flows down the OSI model, it's referred to by different terms. You really have to master these and watch for them on your exams. There are four different terms you need to know :
- At the Application, Presentation, and Session layers, data is simply called "data". (these three layers has nothing to do with the data breaking )
- At the Transport layer, data is placed into segments.
- At the Network layer, data is placed into packets.
- At the Data Link Layer, data is placed into frames.
- Finally, at the Physical layer, data takes the form of bits - and remember, it's all ones and zeros!!!
If I mention "segments", you should know I'm discussing the Transport layer of the OSI model without any other hints, because you might not get any other hints!!!!
As data flows down the OSI model, each layer adds a header that will be removed by the same layer on the other end of the session. These headers are layer-spedific in that the Network layer couldn't care less about the contents of any header except the Network layer on the other end of the session.
As an end user enters data for transmission to a remote host, the first six layers of the OSI model will add a layer-specific header that contains information to be read by the same layer of the OSI model at the remote location. Note that Layer 2, The Link layer, adds both a trailer and a header.
The combination of data and a layer-specific header is called a Protocol Data Unit(PDU). There's a PDU for each layer; that is, the combination of data and L7 header information is called an L7 PDU, the data and L6 header information is called an L6 PDU, and so forth.
After the data is successfully transmitted by the Physical layer to the remote location , the data begins to travel back up the mode. Each layer will remove the header added by its counterpart - that is, Layer 3 removes the L3 header and reads it, L4 removes the L4 header and reads it, and so forth.
The term same-layer interaction describes the process of a give OSI layer removing the header placed on the data by the same layer on the sending side. For example, the Application layer on the receiving end will remove only the header placed onto the data by the Application layer on the sending side, and so forth.The term adjacent-layer interaction refers to the interaction between layers of the OSI model on the same host. That is, the Application layer interacts with the Presentation layer, the Presentation layer interacts with both the Application layer ( the one above it ) and the Session layer (the one below it ), and so forth.
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