Hi, Guys. This is Tadaki. I recently broke my rule to update this blog as early as one month after the start of te blog.
I think it’s important to continue habits when they are broken, so I’d like to share with you what I learned about IT today without regretting my past.
Last time, I talked about computer components. When you talk about a computer, it is a collection of parts that are specialized in one role.
However, no matter how hard one computer works, if the system is not in place, it will not be possible to communicate with other computers. This time, I would like to talk about the “network architecture” that supports computer communication.
If you are good at English, you can imagine what it will do just by looking at the network architecture and letters.
A network means to a communication network between personal computers, and the architecture is a mechanism for realizing that communication. Just as parts are divided according to function in a personal computer, the field in charge of each communication role is different in the network. Then, in the case of computers, the OSI reference model method is unified all over the world within the rules of communication protocol.
The reason why the OSI reference model is unified is that if the communication method is different for each computer, problems such as not being able to exchange emails between a Windows PC and a Mac book will occur. By sharing unified rules between computers, we can enjoy computers comfortably.
OSI reference model is divided into 7 layers in total. The 7 layers are as follows.
| Layers | Name | Roles |
| 7 | Application Layer | File transfer and email transmission / reception that are directly required by application programs and users. |
| 6 | Presentation Layer | Standardize data format (extraction syntax ⇒ transfer syntax). |
| 5 | Session Layer | Common transfer control functions required by communication applications (dialogue management, priority control, synchronization point control, etc.). |
| 4 | Transport Layer | Complement the services provided by the lower three layers and the services required by the upper three layers. |
| 3 | Network Layer | Data communication between terminal nodes. |
| 2 | Data Link Layer | Data communication between adjacent nodes (between two points). |
| 1 | Physical Layer | Physical signal transfer |
I will summarize the detailed roles of each layer at a later date.
Thank you for reading today as well!
1,335 days until 2025.
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