Network architecture
osi reference model: [Internet of Things Shuhui Trial]-This is the formula put forward by Wang Dao’s teacher, a better girl Shuhui tries the Internet of Things
The figure below is a comparison between the osi model and the ip model. Although the osi model was first proposed, it is not biased towards any protocol and is not practical. The ip model is used in practice.
Next, we will discuss layer by layer
Physical layer
The physical layer is also called the "fool layer", and it accomplishes very few functions. This one mainly introduces the basics of communication, including Nai Shi's criterion, Shannon's theorem, etc., and then introduces the transmission medium of the physical layer and two devices
data link layer
The data link layer has many functions. In addition to the three functions, it also introduces the medium access control method and various local area networks, wide area networks and equipment.
Network layer
The network layer has a lot of content, focusing on ipv4, ipv6 and routing protocols
Transport layer
The transport layer talks about UDP and TCP
Application layer
Note that the other layers are not within the scope of investigation. The application layer is not the focus of the postgraduate entrance examination, but it is definitely the focus of the school recruitment interview. The application layer focuses on several protocols.
