Computer Network Architecture

The problem of computer networks is mainly to solve the problem of correct and reliable communication between computers working independently in different regions. The computer network architecture is designed to solve the key problem of computer networks.

For the architecture of computer networks, we must first clarify two concepts: protocols and interfaces. A protocol is a rule between entities at the same layer. A protocol consists of three elements: syntax, semantics, and timing rules. An interface is also called a service access point. A set of protocols and layers is collectively referred to as a service access point.

After years of efforts, the International Organization for Standardization proposed an "open Interconnection Reference Model" in 1984 ". The following describes the hierarchical structure of the ISO/OSI reference model:

ISO divides the OSI reference model into seven layers: physical layer, data link layer, network layer, transmission layer, Session Layer, presentation layer, and application layer.

1. The physical layer involves the original bit stream transmitted on the channel and provides bit stream transmission between adjacent devices.

2. The data link layer is mainly responsible for transmitting frame-based data without errors on the line between two adjacent nodes.

3. The network layer is related to subnet transportation control. One of the key issues is to determine how to select a route from the source end to the target end.

4. The basic function of the transport layer is to receive data from the Session Layer and divide it into smaller units for transmission to the network layer.

5. The session layer allows users on different machines to establish session relationships.

6. The presentation layer is used to complete certain functions.

7. the application layer contains a large number of protocols that are commonly needed.