0, introduction

There are two main types of network hierarchical models, one is academic: OSI seven-layer network model; One is application-oriented: TCP/IP network model, which is divided into four layer model and five layer model.

1. What are the differences between these two types of network layering models?

OSI seven-layer model is put forward by the academic circle, which is known from the number of layers that it divides the network into more details, which also makes its implementation more complex, so its academic value is greater. TCP/IP network model is proposed and implemented by computer oligarchy, which is a simplified version of OSI seven-layer model. Belong to open source product, can provide the user directly to use.

2, TCP/IP four layer model and five layer model difference?

The four-tier model is an industry standard that integrates some of the OSI layers (application layer, presentation layer, and session layer into application layer, data link layer and physical layer into network interface layer) or distributes functions to other layers, so it is more widely used in practice.

The five-layer model is only a compromise method often adopted in learning the principles of computer network, because the OSI seven-layer model has too many layers and is too detailed for learning, and the four-layer model is too simplified, so the five-layer model is proposed by integrating the advantages of OSI and TCP/IP. This is concise and illustrates concepts (you can’t learn the OSI and TCP/IP four-tier model at the same time).

3. Representative agreements at each level?

Appendix I has a detailed chart.As you can see from the figure, the bottom two layers of the four-tier model always have different names, and it is more important for us to understand these two layers.

  • The first layer from host to network layer, also known as network interface layer, is responsible for monitoring data exchange between host and network, that is, receiving data packets from the network interconnection layer and sending them out through the network, or receiving physical frames from the network, taking out IP datagrams and giving them to the network interconnection layer; It corresponds to the data link layer and physical layer in the OSI seven-layer model. In the TCP/IP four-layer model, the protocol of this layer is not defined. Instead, each network participating in the interconnection uses its own physical layer and data link layer protocols. Why is “each network” mentioned here? Because from the physical layer and data link dealing directly with the hardware, and the underlying protocol used by different network types are often not consistent, such as to distinguish between transmission medium according to the wired network (twisted pair/coaxial cable), wireless networks, light nets, etc., as a result of difference of signals, frequency, etc, their data resolution protocol must be different.
  • Network interconnection layer, also known as the Internet layer, as the name implies, is the communication between networks, it is the core of the entire TCP/IP protocol stack, its function is to send packets to the target network or host. This layer needs to address congestion control issues.

Refer to the link

  • Simple and profound – network seven – layer model and four – layer model
  • The network layer
  • *** TCP/IP four-tier model
  • *** Difference between congestion control and flow control

Appendix a