1. What is communication
Communication refers to the transmission and exchange of information between people, people and things, and things and things through certain media and behaviors.
2. What is network communication?
Network communication refers to communication between terminal devices through a computer network.
3. Common terms
| the term |
illustrate |
| data payload |
The final message you want to convey |
| message |
Data unit exchanged and transmitted in the network |
| head |
An information segment added in front of the data payload |
| tail |
Information segment added after the data payload |
| encapsulation |
The process of adding headers and trailers to the data payload to form a new message |
| Decapsulation |
The process of removing the header and tail of the message and obtaining the data payload |
| gateway |
Network equipment that provides functions such as protocol conversion, routing, and data exchange |
| router |
Network device that selects the delivery path for packets |
| Terminal Equipment |
The end device of the data communication system, serving as the sender or receiver of data |
4. What is a data communication network?
A communication network composed of routers, switches, firewalls, wireless controllers, wireless access points, as well as personal computers, network printers, servers and other equipment.
Function: The most basic function of a data communication network is to realize data interoperability.
5. Switch
The device closest to the end user, used for end users to access the network, exchange data frames, etc.
Function: Network access of terminal equipment (PC, server, etc.), Layer 2 Switching (Layer 2 Switching)
6. Router
Network layer device that can forward data packets on the Internet. The router selects an appropriate path based on the destination address of the received message and transmits the message to the next router or destination. The last router in the path is responsible for delivering the message to the destination host.
Functions: Realize communication between networks of the same type or heterogeneous networks, isolate broadcast domains, maintain routing tables (Routing Table), run routing protocols, path (routing information) selection, IP packet forwarding, WAN access, network address translation, Connect to a Layer 2 network built through switches
7. Firewall
Network security device used to control secure communications between two networks. It achieves network security protection by monitoring, restricting, and changing the data flow across the firewall, and shielding the information, structure, and operating status of the network from the outside as much as possible.
Functions: Isolate networks with different security levels, implement access control (security policy) between networks with different security levels, user identity authentication, implement remote access functions, implement data encryption and virtual private network services, and perform network address translation
8. Network division
According to the geographical coverage, the network can be divided into Local Area Network (Local Area Network), Metropolitan Area Network (Metropolitan Area Network) and Wide Area Network (Wide Area Network).
(1) Local area network (LAN):
A network consisting of computers, servers and various network devices within a certain geographical area. The coverage area of a local area network is generally within a few kilometers.
Typical LANs include: a company's office network, an Internet cafe network, a home network, etc.
(2) Metropolitan area network (MAN):
A computer communication network established within a city.
Typical metropolitan area networks include: broadband metropolitan area network, educational metropolitan area network, municipal or provincial e-government private network, etc.
(3) Wide Area Network (WAN):
Usually cover a large geographical range, from tens to thousands of kilometers. It can connect multiple cities or even countries and provide long-distance communications to form a large international network.
Typical wide area networks are: Internet (Internet).
9. What is network topology?
Network topology refers to the structured layout presented by interconnecting various devices (such as computer terminals, routers, switches, etc.) using transmission media (such as twisted pairs, optical fibers, etc.).
According to the topology of the network, the network can be divided into star network, bus network, ring network, tree network, full mesh network and partial mesh network.
