Computer Network review: Topic 1. How does the Internet organize its connection structure?

Computer Network review: Topic 1. How does the Internet organize its connection structure?
1. essential differences between early "networks" and modern networks:
Early "network": Host-centric
Modern Network: group-based exchange network
2. The network and the network are connected through routers to form a network with a wider coverage.
3. computers connected to the Internet are both called hosts and end systems.
4. Data Exchange and forwarding groups through the group exchange network. If a link fails, the group will avoid this link and select another link.
5. Internet structure from a macro perspective:
Edge part:
Host composition, which is directly used by users for communication and resource sharing
Access Network and physical media:
Connect the end system to the physical link (wired and wireless) of the edge router)
△ Core part:
Consists of a large number of networks and routers connected to these networks, providing services for the edge part


6. Communication between hosts (End Systems)-C/S Mode
The host runs the client program and sends the request service instruction to the server.
The server runs the server program and receives the command to provide services to the corresponding host.
Communication between hosts (End Systems)-P2P mode
Host C Requests the services of D, C is equivalent to the customers of C/S, and D is the server
But C also provides services to F, and C also plays the role of server at the same time.


7. Data is transmitted over the network through circuit switching and group switching.

8. China Telecom and China Unicom have only two first-layer Backbone Network ISPs in China


9. There are currently nine backbone networks in China: (learn more)
CHINANET)
China Unicom computer internet (UNINET ),
China Netcom public Internet (CNCNET ),
China Mobile Internet (CMNET ),
CERNET ),
China Technology Network (CSTNET ),
CGWNET ),
China International Economic Trade Internet (CIETNET ).