Computer network-Composition of the Internet, computer network-internet

Computer network-Composition of the Internet, computer network-internet

Computer network-Composition of the Internet

(1) edge part

All hosts connected to the internet.

The communication methods between the end systems on the edge of the network. There are two main types: C/S (B/S is a special C/S) and P2P (peer-to-peer, peer mode ).

Differences:

C/S: Shared Resources in the client/server network can be placed on a dedicated computer-server, and resources are not directly shared between workstations.

The C/S architecture is a typical two-layer architecture. The full name is Client/Server, that is, the Client/Server architecture, the client contains one or more programs running on the user's computer, and there are two types of servers. One is the database server, and the client accesses the data on the server through the database connection; the other is the Socket server, where the program communicates with the client program through the Socket.

P2P: computers can communicate with each other and share resources.

"Peer-to-peer" technology is a new network technology that relies on the computing power and bandwidth of participants in the network, rather than gathering dependencies on a few servers.

? P2P is also short for Point to Point. It is a term for download, which means that while you download your own files, your computer will continue to upload files to the host, the more people there are, the faster the speed, but the disadvantage is that the hard disk is greatly damaged (read at the same time), there is a large amount of memory occupation, affecting the speed of the entire machine.

P2P networks are flexible and suitable for working group-level small networks. When the network size is large, management and security become more difficult. In this case, the Client/Server structure should be used.

(2) core part of Internet

The core part consists of a large number of networks and routers connected to these networks. It provides connectivity and exchange services for edge parts.

Vrouters play a special role in the network core.

A vro is a key component for packet switching. Its task is to forward received packets.

"Exchange" means to dynamically allocate resources of transmission lines in some way.

There are three main methods: circuit switching, packet switching, and message switching ).

1. circuit switching.

Always occupies end-to-endAll resources.

The basic process of circuit switching can be divided into three stages: Connection establishment, information transmission, and connection removal.

2. packet switching.

In the communication process, both parties are grouped and used Storage-forwarding mechanismThe communication method for implementing data interaction is called group switching (PS: packet switching ). Group exchange is also called Packet Exchange. It refers to the data that users communicate. Divided into multiple smaller and longer data segmentsBefore each data segment, add Necessary control information as the header of the Data Segment, Each data segment with a header constitutes a group.. The header specifies the address sent by the Group. After the switch receives the packet, it forwards the packet to the destination based on the address information in the header. This process is group exchange. A communication network capable of group exchange is called a group exchange network. The essence of group exchange is storage and forwarding. It stores the accepted groups temporarily and queues them on the destination route. When it can send information, then, the information is sent to the corresponding route to complete forwarding. The process of storing and forwarding is the process of group exchange. The idea of group exchange comes from Packet Exchange, Message exchange is also called storage and forwarding exchange,The essence of their exchange process is storage forwarding, The difference is that the smallest unit of information for group exchange is grouping, while Packet Exchange is packets.Packet Exchange is faster than Packet Exchange because it is transmitted and exchanged in a small group. Message exchange is mainly used in public telegraph networks.

3. Message switching.

Message switching is an information transmission method. A dedicated channel is not required between two communication nodes for message exchange. NodeThe sent information is organized into a data packet-a messageWhich contains the address of the target node,Complete MessageOne station and one station forward in the network.