Chapter four of our text book describes how data is transferred from one computer to another. What the book is actually discussing (in the most basic sense possible) is the 7 layer OSI model. OSI (Open System Interconnection), model “defines a networking framework for implementing protocols in seven layers.” [1] Each time a computer attempts to transfer data, the individual bits have go through a process twice, once when the data leaves the first computer and once when it enters the second computer. The second time around, the process is done in reverse. The Process is broken down into 7 layers. These layers are:
Application
Presentation
Session
Transport
Network
Data Link
Physical
[2]
Application
Presentation
Session
Transport
Network
Data Link
Physical
[2]The diagram above shows why data goes through the OSI model twice. As you can see, the first time is because the data is being transmitted and the second time is because the data is being received.
In the application layer (7), the user is interacting with the computer to either send data or view received data. The presentation layer (6) takes the data and converts it to a standardized format. The session layer (5) is next. In this layer, communication between devices is established and maintained. After communication has been established, the transportation layer (4) takes over, where error checking takes place. The network layer (3) is next, here is where a determination is made as to how the data will be transmitted between the devices (the route or path that is taken.) The data layer (2) determines what protocol should be assigned to the transmission. The physical layer (1). The physical layer consists of the actual hardware used in the networks. This includes modems, routers and cabling. Once the data hits the physical layer, the process is repeated but instead of the procedure going from layer 7 to 1, it goes from layer 1 -7 and the information is put back together so it can be readable. [3]
I can understand that our textbook is written for a fundamentals class, but I believe that ideas discussed should be addressed by their appropriate names. The OSI model is the backbone of network transmission and should never be overlooked.
In the application layer (7), the user is interacting with the computer to either send data or view received data. The presentation layer (6) takes the data and converts it to a standardized format. The session layer (5) is next. In this layer, communication between devices is established and maintained. After communication has been established, the transportation layer (4) takes over, where error checking takes place. The network layer (3) is next, here is where a determination is made as to how the data will be transmitted between the devices (the route or path that is taken.) The data layer (2) determines what protocol should be assigned to the transmission. The physical layer (1). The physical layer consists of the actual hardware used in the networks. This includes modems, routers and cabling. Once the data hits the physical layer, the process is repeated but instead of the procedure going from layer 7 to 1, it goes from layer 1 -7 and the information is put back together so it can be readable. [3]
I can understand that our textbook is written for a fundamentals class, but I believe that ideas discussed should be addressed by their appropriate names. The OSI model is the backbone of network transmission and should never be overlooked.
[1] The 7 Layers of the OSI Model – September 24th, 2010. http://www.webopedia.com/quick_ref/OSI_Layers.asp
[2] OSI Model Concept – January 8th, 2009 – http://www.petri.co.il/osi_concepts.htm
[3] CompTIA Network Study Guide” Exam N10-004 by Sybex April 13th, 2004
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