Circuit Switching and Packet Switching Networks

2023-11-03 10:48

本文主要是介绍Circuit Switching and Packet Switching Networks,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!

from:http://www.tcpipguide.com/free/t_CircuitSwitchingandPacketSwitchingNetworks.htm

Circuit Switching and Packet Switching Networks
(Page 1 of 3)

In my “grand overview” of networking, I describe networks as devices that are connected together using special hardware and software, to allow them to exchange information. The most important word in that sentence is the final one: information. As you will see in your exploration of this Guide, there are many methods for exchanging information between networked devices. There are also a number of ways of categorizing and describing these methods and the types of networks that use them.

One fundamental way of differentiating networking technologies is on the basis of the method they use to determine the path between devices over which information will flow. In highly simplified terms, there are two approaches: either a path can be set up between the devices in advance, or the data can be sent as individual data elements over a variable path.

Circuit Switching

In this networking method, a connection called a circuit is set up between two devices, which is used for the whole communication. Information about the nature of the circuit is maintained by the network. The circuit may either be a fixed one that is always present, or it may be a circuit that is created on an as-needed basis. Even if many potential paths through intermediate devices may exist between the two devices communicating, only one will be used for any given dialog. This is illustrated in Figure 1.


Figure 1: Circuit Switching

In a circuit-switched network, before communication can occur between two devices, a circuit is established between them. This is shown as a thick blue line for the conduit of data from Device A to Device B, and a matching purple line from B back to A. Once set up, all communication between these devices takes place over this circuit, even though there are other possible ways that data could conceivably be passed over the network of devices between them. Contrast this diagram to Figure 2.

 

 

The classic example of a circuit-switched network is the telephone system. When you call someone and they answer, you establish a circuit connection and can pass data between you, in a steady stream if desired. That circuit functions the same way regardless of how many intermediate devices are used to carry your voice. You use it for as long as you need it, and then terminate the circuit. The next time you call, you get a new circuit, which may (probably will) use different hardware than the first circuit did, depending on what's available at that time in the network.

 

 

Packet Switching

In this network type, no specific path is used for data transfer. Instead, the data is chopped up into small pieces called packets and sent over the network. The packets can be routed, combined or fragmented, as required to get them to their eventual destination. On the receiving end, the process is reversed—the data is read from the packets and re-assembled into the form of the original data. A packet-switched network is more analogous to the postal system than it is to the telephone system (though the comparison isn't perfect.) An example is shown in Figure 2.


Key Concept: One way that networking technologies are categorized is based on the path used to carry data between devices. In circuit switching, a circuit is first established and then used to carry all data between devices. In packet switching no fixed path is created between devices that communicate; it is broken into packets, each of which may take a separate path from sender to recipient.

Figure 2: Packet Switching

In a packet-switched network, no circuit is set up prior to sending data between devices. Blocks of data, even from the same file or communication, may take any number of paths as it journeys from one device to another. Compare this to Figure 1

 

 

Comparing Circuit Switching and Packet Switching

A common temptation when considering alternatives such as these is to ask which is “better”—and as usually is the case, the answer is “neither”. There are places where one is more suited than the other, but if one were clearly superior, both methods wouldn't be used.

One important issue in selecting a switching method is whether the network medium is shared or dedicated. Your phone line can be used for establishing a circuit because you are the only one who can use it—assuming you can keep that pesky wife/husband/child/sister/brother/father/mother off the phone.

However, this doesn't work well in LANs, which typically use a single shared medium and baseband signaling. If two devices were to establish a connection, they would “lock out” all the other devices for a long period of time. It makes more sense to chop the data into small pieces and send them one at a time. Then, if two other devices want to communicate, their packets can be interspersed and everyone can share the network.

The ability to have many devices communicate simultaneously without dedicated data paths is one reason why packet switching is becoming predominant today. However, there are some disadvantages of packet switching compared to circuit switching. One is that since all data does not take the same, predictable path between devices, it is possible that some pieces of data may get lost in transit, or show up in the incorrect order. In some situations this does not matter, while in others it is very important indeed.

While the theoretical difference between circuit and packet switching is pretty clear-cut, understanding how they are used is a bit more complicated. One of the major issues is that in modern networks, they are often combined. For example, suppose you connect to the Internet using a dial-up modem. You will be using IP datagrams (packets) to carry higher-layer data, but it will be over the circuit-switched telephone network. Yet the data may be sent over the telephone system in digital packetized form. So in some ways, both circuit switching and packet switching are being used concurrently.

Another issue is the relationship between circuit and packet switching, and whether a technology is connection-oriented or connectionless. The two concepts are related but not the same; the next topic discusses this in much more detail.

 

 

Note: Note that the word “packet” is only one of several terms that are used to refer to messages that are sent over a network. Other terms you will encounter include frame, datagram, cell and segment.

 

 

 

 

这篇关于Circuit Switching and Packet Switching Networks的文章就介绍到这儿,希望我们推荐的文章对编程师们有所帮助!



http://www.chinasem.cn/article/337643

相关文章

音视频入门基础:WAV专题(10)——FFmpeg源码中计算WAV音频文件每个packet的pts、dts的实现

一、引言 从文章《音视频入门基础:WAV专题(6)——通过FFprobe显示WAV音频文件每个数据包的信息》中我们可以知道,通过FFprobe命令可以打印WAV音频文件每个packet(也称为数据包或多媒体包)的信息,这些信息包含该packet的pts、dts: 打印出来的“pts”实际是AVPacket结构体中的成员变量pts,是以AVStream->time_base为单位的显

A Comprehensive Survey on Graph Neural Networks笔记

一、摘要-Abstract 1、传统的深度学习模型主要处理欧几里得数据(如图像、文本),而图神经网络的出现和发展是为了有效处理和学习非欧几里得域(即图结构数据)的信息。 2、将GNN划分为四类:recurrent GNNs(RecGNN), convolutional GNNs,(GCN), graph autoencoders(GAE), and spatial–temporal GNNs(S

Circuit Design 贴片晶振的区分

贴片晶振脚位的区分(非常详细,尤其是如何区分四脚的有源无源晶振): http://ruitairt.com/Article/tiepian_1.html 如何区分有源和无源晶振: http://ruitairt.com/Article/yzjddbfqsq_1.html

Circuit Design RC 震荡电路

为了测试一个信号放大器,手边又没有合适的信号发生器,所以就需要自己手动来一个信号发生器。。。。。由于所需的频率大概也不会太高,手边也没有电感,所以选择用RC震荡电路来实现这个功能。 借鉴的网页: http://www.eepw.com.cn/article/283745.htm RC振荡电路,采用RC选频网络构成,适用于低频振荡,一般用于产生1Hz~1MHz(fo=1/2πRC)的低频信号。

Circuit Design 三极管驱动蜂鸣器电路 及 蜂鸣器两端电压正确但是不响的解决方案

利用三极管进行电流放大的蜂鸣器驱动电路图: (百度图片找的) 我用有源蜂鸣器实现的这个电路,但是蜂鸣器不响。 details: 1. VCC =5V 蜂鸣器两端的直接电压约为4.5V, 但是蜂鸣器不响。 2. 将蜂鸣器直接接在4.5V的电源两端,蜂鸣器响。(说明蜂鸣器是好的) 3. 测了三极管各个管脚的电压, 和理论上的是一致的。 情况很奇怪,换了好几个三极管结果都是一样的,

Complex Networks Package for MatLab

http://www.levmuchnik.net/Content/Networks/ComplexNetworksPackage.html 翻译: 复杂网络的MATLAB工具包提供了一个高效、可扩展的框架,用于在MATLAB上的网络研究。 可以帮助描述经验网络的成千上万的节点,生成人工网络,运行鲁棒性实验,测试网络在不同的攻击下的可靠性,模拟任意复杂的传染病的传

Convolutional Neural Networks for Sentence Classification论文解读

基本信息 作者Yoon Kimdoi发表时间2014期刊EMNLP网址https://doi.org/10.48550/arXiv.1408.5882 研究背景 1. What’s known 既往研究已证实 CV领域著名的CNN。 2. What’s new 创新点 将CNN应用于NLP,打破了传统NLP任务主要依赖循环神经网络(RNN)及其变体的局面。 用预训练的词向量(如word2v

【机器学习】生成对抗网络(Generative Adversarial Networks, GANs)详解

🌈个人主页: 鑫宝Code 🔥热门专栏: 闲话杂谈| 炫酷HTML | JavaScript基础 ​💫个人格言: "如无必要,勿增实体" 文章目录 生成对抗网络(Generative Adversarial Networks, GANs)详解GANs的基本原理GANs的训练过程GANs的发展历程GANs在实际任务中的应用小结 生成对

Image Transformation can make Neural Networks more robust against Adversarial Examples

Image Transformation can make Neural Networks more robust against Adversarial Examples 创新点 1.旋转解决误分类 总结 可以说简单粗暴有效

【UVa】 10735 Euler Circuit 混合图的欧拉回路 最大流

题目链接:http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=1676 题目要求:求混合图的欧拉回路+输出路径。 题目分析: 先看一段比较流行的说法吧~: -----------------------------------------