Wagner, with only a link. Bacon So the number of Charlie Chaplin bacon for 3. Further deduce down, we found that Paul “of the proms number 4, the bacon is the proms ever was in” ~ is a number of 13 to negotiate with the leg-..? The documentary plays himself. Actor list includes jean Paterson, in which is as myself from himself. Paterson later in the film “the moon treasure box” ‘ 8 Chi seems like such as generation-II tree a small role evolved, through the film, he’s got the bacon several 3. Since the is a number of the documentary about is the graph theory, therefore, a large group of mathematicians has not only a small number of the proms, and there are a very small number of the root.

If it weren’t for two computer professional students just see the Stewart show, bacon game may be over. University of Virginia glen ‘walter shaw and Brett’ ogaden was immediately realized, judge between any two actors 6 silks can be used as a feasible computer research projects, the premise is to have all the actors and release movies database. The Internet movie database (change “to claw Fletcher… 0 coffee!) Feet , namely shut claw, is a gold mine of fans. Here, they can to actor and film query almost all information. Watson and ogaden spent weeks out, “bacon’s oracle,”Web site that became a discussion of the distance between the actors ace web site. On the web site input any two name of actor, it only takes a few milliseconds time, website can plan Bi out of the shortest Apple A1281 battery path between them, and gives a contact their play farmers and movie name. In a very short period of time, the website of the day traffic, more than 20000, and in 1997 was named time magazine of the year. I recently ten best web site a post your the web site is in on August 26, 2001, the day of the traffic is 13000.

Kevin bacon game is able to play “up, because Hollywood is a circle the stomach, forms highly stomach close related network, in the network, the actor will phase , they were in node starred in film together. A movie actor and actress in a I list all the rest of the cast contact together. Such a Yin too much of the film actor soon accumulate a huge link network. Actors, the average links in 27, which is more than the minimum, forms a network that links, to be much higher, so the network inevitably there will be six degrees this network, every actor can through the average three links and any other ? 0 connected together with silk. However, my research group in the research network” actor “and to” for the network, the average doesn’t work. 41. Stone’s many actors links. The actors at least 10 is not so well known in the position in the table, the actor is by the audience, often after coming out of the cinema, their names to be there. But a small part of the actor’s link far more than 10. John “Carla d the prolific actors accumulated 4000 links life; Robert ‘m Tim Fletcher in life, and 2905 colleagues acted in movies. This contact rich actor is good, the center of the dock only remove the node, the few, contact to bacon’s road size will greatly increase the length.

From a point, we can judge, played most of the film actor, contact the most, and Hollywood other actors distance the shortest. In general, this a judgment is right: a character as the more plays, he and his colleagues average distance of the shorter. But, as the most actors play list was not contact the most actors, how much this also some let us surprised. ZhengHaoXiong edit the top 10 list below, which in part in brackets are they as a number of films: MEL brown ugly muscle to . (the , Tom. Byron the today), mark ‘Wallace sorrow, honor. Jeremy (only 6 “optimal-((4), Peter’ think 1 01110 490, fourth rides. D. 80 (measures sockets), Tom ‘London ( claws! ) [436 Yi randy’ wise, 680 425. HuoNa (like mike ” 9017160 (measures…) and jay. Hill aston villa new generation Yang) “sichuan). I to bet on said, men of most of the name may be here, we were not familiar with the same, for him are simply do not understand. Everybody was perhaps a bit familiar to brown, he gave a lot of cartoon Angle color match a noise, like” peanuts “series, and the confused the collapse of a guest tamiflu duck, three little pigs, etc. At the age of 50 years old of readers may have seen Tom London, when he is the most prolific western actor, as a governor, ranchers, etc. But for the 1 role the list of most actors, but we didn’t cooked noted. After some investigation, we finally find out the details of their. That they are level 3 piece of star.

The actor watch may well, is that once the involves network, scale doesn’t draw, is the most important factor. Although these level 3 piece of star as a number of films surprised people, but they just can’t near the center of the Hollywood. Due to the existing cluster phenomenon, only network in cluster nodes connected node, may in their circle in the center position subculture. If lack link to the outside world, they pick up mouth other nodes in the distance of each node is far from the distance. So, for only the star in x-rated slice, if he only and other x-rated slice star have league department, it’s difficult to put the he and Martin scorsese ‘ 86 or ender fierce-tal can kabalevsky (eight of the scene and sing in the film actor is connected, they are in the different world. The network really given the center reserves in DuoGe large cluster have their place of nodes. For actor nets collaterals, this node is the DuoZhong types as a film actor. For ten thousand, the node net d is that not only provide modern art links, but for the people of all questions to provide links. To society, this node is the kind of and various areas of the people have the company. They are in the proms, this kind of person never limited to any frame, multidisciplinary related topics for, they can freely. They are in the network of’ Da Vinci, whether to art or science have become adept.

Of course, bacon was a Hollywood important actor. He starred in the movie, with 46 accumulated 1800 and the link between the other actors. He was reconciled, any actor’s average interval is a 2.79-that is, most of his stomach is in only three links. Therefore, some people can put Kevin bacon game to play, “1 is good, because any actor and he were easy. Link However, silk and silk is not contact the most actor? ZhengHaoXiong do contain 1000 connections and the most and actor table (this is after Hollywood’s real core , we quite expend some of kung fu, just find bacon. In the first place was, “110 rhode-tiger , he and all the others average distance is 2.53. Donald ‘general,’s” fairy, remember? A optimal II sorrow) the average distance is 2.54, the second. The next machine (milk is Martin’ , Christopher lee the pillow…., Robert ‘m Tim Fletcher , and Chad, d.v. “on heston (Mang strong , their value is less than 2.57. We look through the hundreds of names, turned over more than ten pages, also didn’t see bacon name. Finally we in the bottom of the list to find his place, is 876.

Why are we still take Kevin bacon is a thing? Actually the name of bacon by sheer chance, mainly Lenovo IdeaPad Y460 battery to Stewart show brought him fame. The actors and most other actors have between three links, bacon is no extraordinary. He not only not in the center of the universe, is not in the center of the Hollywood.

Random universe does not exist the connection. If society is random, so in the case of Mr Rudd will only 400 people social model, everyone’s average links for 39, then the most good at communication links is the society should be much less than 118. If the world wide web is random network, then a web page with 500 points to it the possibility of link is 10-that is, for zero chance, this means the array in stochastic network, don’t allow the existence of the node center. However, a recent make of a network, covering the Chad less than 1/5 of the entire web, only to find that the network has 400 center web page, and there is a document with 2 million points to it by the chain. In the random network to find such a node in the whole universe is equivalent to the chance of a particular atoms find “. If Hollywood is random network, the tiger, the actor will should not be there, because there is the possibility of such actor is about 120 this number is too small, are not good can find to describe it analogy. It is in these data by incredibly small, so we early trying to understand the real nets and silk in the world wide web and Hollywood structure, network found center, we will node of the life surprised. We have no preparation, because whether the proms riley was based on, or watts-stowe’s model, and is not allowed to the existence of the node.

Since the discovery of the existing in the world wide web center, the researchers began to node search many other fields of center node. The result is quite by surprise: now we know way, Hollywood, the world wide web, the society and so on, from any Angle, is not all don’t speak with. For example, in a cell, through chemical reaction networks of molecules form existing in the heart of the node. A small portion of molecules, such as water molecules or three phosphorus adenosine six?, he rides the cells of tiger, is involved in the big games, they react. On the Internet, will the world’s computer connected together in line, there are also a few network nodes. They are the center of the role of the Internet is vital, and ensure the high reliability. Amy’s is the center, in the node, 507 of the proms mathematicians number one. According to the American telephone &telegraph company a study, a few phone number hit or answer the phone, this great II mainly including phone sales company and customer service electricity words etc. In most scientists have studied in the complex network, there is center section points. They are common, we become the surrounding complex connected world of gene characteristics.

And to center of the node cause pay special attention. Iraq to say good connection Manuel of the role. In his book “the marketing all by a mouth” Fletcher

, handsome “”he spent several chapters of the center section of social network

And, according to the class is that they are spreading news and the role of lies. The United States once every four years will be announcing a new social center of a node was born? Eye s new President. Franklin Roosevelt ^ ‘draenor contact list of 22000 names, and this made him become his day’s largest center node. Recently, have three important biologists in the prestigious journal nature, put forward some of the molecules of the attributes of the node similar centers such as the protein, is human from molecular water flat understand many types of cancer pathological key. Ecologists think, the center of the food chain node is one of the key species, this species conservation and ecological system for the firm to settle work.”

Center are so pay attention to node is taken for granted. Center node is special, in any existing node of the network, the center of all of them network structure, played a key role that the networks are the characteristics of small world. Center nodes and unusually more links between nodes, for the system Toshiba PA3399U-2BAS battery in any two nodes to create contact. The result is that the global, the random choice of the distance between the two is 6, and any one of the connection and the distance between the is 1 or 2. Similarly, in the world wide web, two any page’s the distance between 19 and any web page, click from turn to yahoo needed click is 2? 3 times. From the center to observe the world, node it is very small.

For decades, many people were the proms and riley, think that the Internet is the influence of the machine with. Recently this view in many ways has been challenged. Watts and stowe and watts model put forward concerning the simple explanation of cluster, the random network and cluster phenomenon unified up, center and the network node further change the state of the research. We mentioned so far the two models are unable to explain the existence of the central node. Therefore, the center node forces us to rethink about network knowledge, and put forward three fundamental questions: how is the center node in? In a set of network, might be an how many center now nodes? Why the previous model can foresee the existence of the node center?

Over the past two years, we try to answer most of the questions. We found that, the center section points and not connected with each other in the universe of rare coincidence. Instead, they comply with the existence of strict mathematical laws’ their widespread force us with new ideas to consider the problem of network. Revealing and explain the process of these laws, experience up like a roller coaster, from which a stimulus, we understand more about our complex to each other in the world. These knowledge, than in the past years of accumulation of combined.

Network TV is the Internet technology and TV technology with the product, so, it will both advantages are set at a suit. It has the following features:

(1) network TV inherited the interactivity of the Internet features. This includes IBM Thinkpad R60 battery both the interaction between the audience and network television request and response, also including the interaction between the audience. Traditional TV audience didn’t choose the right program, and could not skip the commercial breaks. In network television, audiences can choose according to the program shows and broadcast order, and the programs of also can not make an appointment. Network TV to watch TV programs, in the audience can through the relevant web site for added information, still can talk to other people, and feel; In watching football match can get some athletes relevant information, also can see the relevant statistics; Watch singing program is can see the singer resume, show the lyrics, also can buy the songs online the laser discs; Watch the son children program, animals can answer the questions, with printers print out of the picture, and into line painting, etc.

(2) network TV can provide more excellent audio-visual effects. Network TV inherited traditional analog TV image visual and vivid flexible characteristics, and can output than traditional analogue TV more high-quality image and sound effects. At present our analog TV only about 350 lines of resolution. Network TV image quality can reach a television studio quality level, to more than 1200 lines of resolution, carrier image mass can achieve DVD quality. Network TV sound quality is very high, can support 5 channel or higher.

(3) network TV marketing mode is to belong to a pay TV. Despite the cable TV users also have to pay, but this is the result of the cable TV network access, and not the channel and the service content to charge. Network television will not be allowed to commercial breaks, and according to the audience’s interest hobby, the FenShiChang fine and no advertising program will surely increase the narrow the TV channels operation, and network TV into the channel is a paid. Network TV service charge in addition to nets fee, but also including channel or program subscription fee. In addition, the network TV can carry a lot of increasing value services such as interactive games, gaming, securities business, TV bank business, TV bought things such as business services, these services are also usually Asus W7 battery requires a separate pay for it.

(4) network TV can carry a lot of service platform. Network TV service platform is the traditional TV can bear the weight of the service content. This some operations in network television, Internet and value-added service is a combination of network television, or network TV from Internet services directly reference to come here. Value-added services can be remote education, video conference, remote medical treatment and network games, online shopping and so on, these can carry on network TV platform, and traditional TV cannot provide such services.

Network status

Packet switching is post and telecommunications departments construction and development of the earliest based data communications network collaterals. Switching to CITTX25 Suggestions for group based, can satisfy different rate, not the end with the computer, the computer and the computer room and communication between the local area network. Packet switching is a foundation of the data communication network, the network platform can structure various value-added services, such as E-mail, electronic data exchange, fax store-and-forward, etc.

ChinaPAC by national backbone and the provinces (city, area) of the province nets. Before covering all eyes between backbone, capital city of the province, covering a business requirements to network of cities and towns have developed. Through the Internet and telephone network, ChinaPAC can cover the telephone netcom reach all parts of the. ChinaPAC exchange center and a level 1, level 2 change center in exchange center between the incomplete mesh structure, level 1 exchange center to the respective level 2 exchange Lenovo G450 battery center between the star shape structure; ChinaPAC in Beijing and Shanghai, guangzhou has a international inward to Hong Kong and Macao regions, to complete the entrance with international data networking.

The network characteristics and functions

Packet switching is the advantages in a physical electrical lines and open multiple virtual circuits, for DuoGe users use at the same time; Network has dynamic road out of function and complex complete error correction function. X.25 agreement is in physical link transmission quality was poor affection condition developed, in order to guarantee the reliability of the data transmission, it in every period of links to enforce a mistake inspection and error retransmission; This kind of complex error verification mechanisms although make the transmission efficiency of it is limited, but really for the safety of the user data transmission provides a good protection.

ChinaPAC provide business as follows:

Basic business functions

Basic business function is pointing to any numeral terminal equipment provides basic business functions. It can satisfy user communication basic requirements. There are two kinds of basic business, exchange type a virtual circuit; Permanent virtual circuits.

Choose a business function

Users choose a business function is to meet the special needs of customers, provide special business functions, such as the FengZu, a call FengZu call, one-way into the logical channel, one way out of the logical channel, etc.

The other business functions

Chinanet also provide other fee ITU-T suggested business functions, such as virtual private network TCP/IP packet multiple address broadcast, call redirection, etc. The net users Chinanet way provides two access. Line way

Apply to communications portfolio is large, heavy use of the high demand, applications, but need to use special line, the relatively high cost. Special line for 9.6-64 net rate kbpa. dialup

Apply to business is not big, intermittent period is longer, can tolerate failure should use the call. Because of its use the existing phone lines, the need for additional investment, and data can be Shared with voice lines, thus greatly saving investment, users are ideal for scattered the access method. Can be divided into X. 28 HP f500 battery asynchronous dial-up access or X. 32 synchronous dial-up into the net, net dial-up speed rate for 1200-9600 BPS.

Fees policy

ChinaPAC current have two kinds of charging methods, one is the timing measurement fee, 2 it is the bag fee on system.

And DDN frame relay compare, business group is cheaper, charges it is the user structure its internal wan the most economic a choice. In the need to build at the same time a multipoint connection, through the group of a virtual circuit switching function, can replace expensive more DDN line.

China public digital data networks

Digital communication network is using digital channels provide permanent, half permanent connection, to transmit data signal digital transmission network mainly. It can provide each kind of flexible data interface for transmit data service signal. Because of its simple, rate is higher, agreement in our country have developed rapidly.

By digital channels, DDN DDN node, network management system and the subscriber loop, it provides of point-to-point and point to more digital special line business, can also provide frame relay and compressed voice/G3 fax service. The main features are: DDN

Transmission quality high, because at present by using optical fiber transmission channels of DDN, 1 have to transmission quality is much improved;

The transmission rate is high, the rate between 2400 BPS-2 Mbps between; Agreement simple. Because the time multiplex and DDN main cross connection | technology

Art, the transparent to the user information transmission, and the technical requirements of users less flexible, application;

On the net, and with motions DDN advanced network technology, the line scheduling, fault

Monitor can realize the centralized management, the line of fault when still can automatic routing circuitous, users of the circuit to high utilization rate.

DDN mainly provide point-to-point digital special line business. Widely used in the silver line, securities, weather, cultural education, etc, and is suitable for the mutual lans and wans, different network interconnection al etc. For example, a company’s headquarters is in a different place and division, the communication between two points and very frequently, not only wanted to keep telephone links, and computer network communication. If renting a DDN line ends, and set the distribution for reuse, both the telephone system and computer system, can link up in two to convenient communication between. Such already save between two of the long distance telephone charges, and can realize the interworking computer system.

DDN also provide more business, mainly refers to the business, two-way radio more business (multipoint polling; and the conference TV business. Radio more business features are: data information flow in from point to transmit can be more, make more and get the same information. Multicast business apply to information issued < stock, news, weather forecast, etc); . Two-way more business mainly refers to a stood a moment can and a two-way communication from the station master station regularly visit from a standing, and from standing exchange information. Two-way communication business applies to more concentrated surveillance, credit card verification, and data services, reservations system, etc. The meeting is to use the TV business multipoint bridging DDN functions more images and the exchange of information such as voice. The meeting television system each site can serve as main communication with other sites, but a moment there can only be one host. More Dell 9400 battery business characteristic is, a point the only a interface can finish and more communications, saving client equipment and network resources, and reduce the information technology. In addition, use the online DDN frame relay resource module and words sound compression module, still can realize open frame relay business and compressed voice/G3 fax service industry.

China public frame relay nets China public frame relay broadband business backbone is China’s first will be provided to the public service of the data communication network, the broadband of our country will put into production of the informationization of the national economy have a positive impact on our country’s information, will become an important part of highway.

ChinaFRN provides more than 64 K in high speed data communication services. Business types can be an unexpected, also can be the real time.

ChinaFRN can also be for other data communication network provide high-speed relay transmission, make each network performance can strengthen, and improve the efficiency.

China public frame relay broadband business the backbone of the main characteristic is a team, ATM technology platform with, meanwhile, we also provide frame relay and believe yuan relay, etc. China public frame relay broadband business the backbone of the main technical features include:

Equipment advanced, integral sex is good single network, take the network connection backbone hub.

Network full range of business, provide frame relay PVC, ATMPVC and basic business SVC.

Port complete kinds, wide range of speed. To frame relay business, network provide the interface types including V35, X. 21, E1, channelized E1, ISDNPRI, E3, etc. For ATM business, provides the network interface type have E1, E3, STM-1, etc.

The user access is flexible. Support frame relay or eight agreement can directly access terminal equipment; LAN routers, LAN switches can be through direct access; Other agreement terminal can be through the FRAD equipment to access. In addition, because network port itself FRAD function, support built-in HDLC, SDLC and PPP agreement also direct access to the terminal.

Support frame relay ATM communication function.

China science and technology network

China science and technology network experienced four no word of the development stage, namely NCFC engineering,

CASnet, CERnet, CSTnet.

The network is we communicate, Narrows bridge and the space and time; Nets winding is human exchange of information facilities; The network is the basis of electronics, equipment, cable and agreement.

About the computer network, the americans have ever given a standard definition: “network is connected to each other the autonomy of the set of computer.” The reason this definition “standard”, because almost all of the network course in university, when introduce the concept of network to mention this sentence.

This definition has three key content: connect with each other, autonomy, and computer. We can say more specific point, the so-called computer network, is to use communication and line for a different geographical position, function of independent DuoGe HP CQ50 battery computer system interconnection up to the function is perfect network software (i.e., network communication protocol, information exchange network operating system and way of sharing resources network) and information transmission system.

Should say, the definition of network as the change of time and develop. Early, people will be dispersed computer, terminal and affiliated equipments, connected by using communication medium, can realize mutual communication system called network.

In 1970, in the United States at the information processing association spring computer joint meeting first gives a be accepted definition: “network is to share information source (hardware, software and data, etc > way connected with independent, and their respective functions of the computer system of the set.”

The aim is to build up a network resource sharing, and this is the nature of the network,

The definition of computer network involves the following four points: in a computer network contains more than two sets of different geographical position with “autonomy” function of the computer. The so-called “autonomy” meaning, it is to point to the computer does not depend on the network and be able to work independently. Usually, will have “autonomy” function of the computer says, in the network mainly machine is also known as the node. The network node is not only the computer, also may be the other communication equipment, such as, on, routers;

Each node in the network the connection between the need to have a way, that is, by the transmission medium to achieve physical interconnection. Article the physical channel can be twisted pair, coaxial cable or light fiber, etc “cable” transmission medium, also can be the laser and microwave or satellite, “wireless” transmission medium;

Each node in the network communication between each other or exchange information, need to have some agreement and rules, these conventions and the set of rules is the agreement, its function is to realize the quarter point of logic interconnected. For example, Internet use on the communication protocol is the TCP/IP protocol;

The computer network is based on data communication and network resources to realize (including hardware and software resources information source > sharing for the purpose to achieve this purpose., network the need to have power can improve network software, including the network communication protocol and network operating system.

The computer network is the computer technology and communication technology, the combination of the this is mainly embodied in two aspects: on one hand, communication technology for computer data transmission and exchange between provides the necessary means; On the other hand, the development of computer technology to penetrate the letter in the technology, and also to improve the communication network in all sorts of function.

The development of computer network process can be divided into four stages: the first stage, with a single computer as the center of the remote online system, a computer network for terminal (the 1950.

In 1946, world’s first electronic computer ENIAC was born in the United States, the computer and communication technology project technology and no direct link. In the 1950 s, the beautiful countries in order to its own security, in the United States and Canada northern territory, established a semi-automatic ground air defense system, the SAGE computer technology and communication technology, the combination of trying.

The people with the individual computer as the center of the online system called for the remote terminal online system. The system is a computer technology and communication technology, combining the form the prototype of the computer network, so also called for the computer terminal communications network. The 20 th century 60 s American airline reservation system SABRE-1 is the typical application of computer network communication network, the system by a computer and distribution center in the United States within the scope of the 2 000 DuoGe terminal composition, the terminal through telephone lines connected to a central computer.

With communication function of single machine system is the typical structure of computer through multiple lines controller and a remote terminal is linked together, along with the rapid development of computer and network, the size of the increase with the center for single remote online system soon exposed its inherent disadvantages:

The host should not only responsible for data processing, and management and terminal communications, burden, can not adapt to a large number of data processing tasks;

Each terminal used alone a root line, line utilization rate is very low, especially when it is the end of the links to increase the number of causing certain investment pressure;

Lines of software and hardware not universal, controller when access terminal, need to change to making a large adjustment.

To reduce the burden of the host, in the communication lines and between computer set to an FEP processor, the former special charge and terminal of communication between the control, and let the Lord machine data processing; In order to improve the communication efficiency, reduce communication costs, in a remote terminal most densely populated add a focus, focus on the role of the device is to place several a terminal at low speed on the communication lines up, connected to the high-speed lines, and then, after the high speed line road and front-end processor connection. Front and concentrators, the common processor by a small computer bear, so, the structure also called has the correspond dencefunction many system,

By definition, in the first stage of development network with single center for remote online system cannot be called the true network. On this point, in the field of network technology has become a consensus. But the system has the essential feature of the network resources sharing, also is the prototype of the network development and the foundation.

The second phase, DuoGe autonomy function host through the communication lines, formation of the Internet information sharing source of computer network (the 1960 s).

In this stage, realize the Internet, thus forming the real computer network. At the same time, during this period, there was a in the history of network often overlooked but for the development of the network landmark event: resources and communication subnet subnet separation.

Communication subnet and resources, eliminate the subnet separation technology barriers, to avoid the network of monopoly, reduce the network technology, a large number of outstanding threshold to the manufacturers, research institutions and scientists in the field, the network is human HP Presario c700 battery society, the network technology to the rapid development of the very important basis.

What, then, are the resources subnet and communication subnet?

By all of the network resources subnet host, terminals, terminal controller, peripherals such as; network printers, disk array, etc.) and all kinds of software resources, responsible for the entire network of several according to treatment and to network users (workstation or terminal) provides the network resources and services.

Communication subnet of communication equipment and the circuitry for resources, the data transmission, allowable subnet and transform and other communications work.

The third stage, form a unified network system structure, follow the international standardization agreement (the 1970 s computer network; ) .

The third stage of computer network development is accelerated system structure and agreement of international standards of the research and application. At the end of the 1970 s, ISO’s computer with XinXiChu

Richard standardization technical committee established a special institutions, research and make network communication standards to achieve the network system structure of international standardization. 1984 ISO formally promulgated a called “open systems interconnection basic reference model of” international standards, “ISO7498 OSI RM, the famous OSI seven layer model. The OSI RM and standard agreement and improve dramatically accelerated the development of computer network. Many large computer manufacturers have announced its support for OSI standards, and actively research and development conforms to the OSI standard product.

Follow the international standardization agreement with united network of computer network system and structure, the manufacturer should be recognized in accordance with the international standard develop their own network products, which can ensure the different products can be in same communication network. This is the meaning of “began to put”.

At present there are two dominant network system structure: one kind is the international standard organization must change ISO proposed OSI RM (open system interconnection reference model >; another kind is Internet use in fact industrial standard TCP/IP RM (and test model).

The fourth stage, to the Internet, high speed, intelligent direction development of computer network (beginning in the 1980 s >.

From the end of 1980 s, computer network technology into the new development order section, its characteristic is: Internet, high speed and intelligent. Displays in: development with the Internet as a representative of the Internet; High-speed network. In 1993 the United States government has announced a “national information infrastructure” action plan, namely the information highway plan. Here the “information superhighway” refers to the large capacity of optical fiber communication network digital, to put the government institutions, enterprises, universities, scientific research institution and the family of the computer network project. The United States government and respectively in 1996 and 1997 to investigate more quickly and with the development of Internet 2 and the next generation of the Internet.

Can say, the network interconnection Dell Inspiron 1464 battery and high-speed computer network is becoming the latest generation of the development of computer network direction;

Research intelligent network. Along with the increase of the network size and network service function, increase of the number of countries is developing intelligent network of IN research,

In order to improve the communication network began to send business ability, and more reasonable network all kinds of industry affairs management, true to distribution and open forms to customers. Intelligent network is the concept of the United States in 1984, put forward the definition of the intelligent network and no people usually Richard solution “intelligent” meaning, it is just a kind of “network”, the purpose is to improve the communication network development business ability. The emergence of the world telecom department has caused the attention of international report couplet additionally began in 1988 as its research subject. 1992 the formal definition itu-t T intelligent network, made a fast, convenient and flexible, economy, have effect to generate and implementation of new business system. The goal of this system is applied to all communications network; That not only can be applied to the existing network, N-ISDN nets and group nets, also apply to mobile telecommunication network and B-ISDN nets. With the passage of time, the purpose of intelligent network applications to a higher level.

The communication medium can be divided into two categories: cable medium and wireless medium. Cable transmission medium is using of cable or optical fiber cable conductor transmission interface as the transmission quality, such as twisted pair, coaxial cable and optical fiber cable; Wireless transmission medium is using of electric wave or light transmission of media as a conductor, such as radio waves, microwave, and infrared and satellite communication, etc.

Transmission medium to the performance of the network has a bigger impact. Measure the transmission medium of the main technical performance indicators are: the transmission distance, transmission bandwidth, anti-interference ability, connecting method and price.

(a) twisted pair

Twisted pair is currently the most widely used medium Ethernet. The popularity of the twisted pair with the success of the hub and switches and realize. Telephone cable is twisted pair.

The basic principle of twisted pair is stick with insulating copper wires for the use of for a (stranding machine) according to certain specification intertwined with each other.

In a twisted pair speaking, when the outside electromagnetic signal in PA3399U-2BAS battery the two wires produce dry interference signals equal and opposite phase, jamming signal will offset each other.

Used in network of twisted pair, there are eight line, every two root twisted together.

Twisted pair has two kinds: the shielded twisted-pair cable and shielded twisted-pair cable. Shielded twisted-pair cables external package has a metal nets, used to shield the external interference. You put the phone with metal teacup cover up immediately, you can’t hear anything, it is this principle.

But the most popular are shielded twisted-pair cable, because the shielding twisted pair of the effect is not obvious, and the cost to high. Shielded twisted-pair cable at present general used only for industrial control field. About the standard of Ethernet have different versions, each version required cable specification and the transmission distance is different. Basically, use twisted-pair cable connection, dozens of meters to more than one hundred meters between the is reasonable.

(2) coaxial cable

Coaxial cables are the most widely cable TV network, but the computer network, the coaxial cable and network with the specification is not the same.

The interior of the coaxial cable has a copper-core as conductor, filled with middle of the insulation material layer is plastic, plastic layer is shielded network, and external as another wire, the cable from PVC or teflon material to cover the sheath.

At present more commonly used have two kinds of coaxial cable: a 50 cable, used for several words transmission, also known as “baseband coaxial cable”; Another for 75 cable, used to model the transmission, to is also referred to as a “broadband coaxial cable”.

Coaxial cable has very good anti-interference characteristics, the signal attenuation is less than twisted pair, can further distance transmission. In the etheric network have used two kind of coaxial cable, one kind is thick cable, and the other is the fine cable, thick cable is more good transmission characteristic.

Coaxial cable in the local area network applications with twisted pair and the popularity of the optical fiber has been eliminated.

(3) fiber

Optical fiber is the most promising transmission media outlets that almost all of the new network trunk are using optical fiber technology. Optical fiber to the desktop refers to use fiber instead of twisted pair computer connected to the Internet.

Optical fiber is in the form of a light pulse signal transmission, and the material is glass or plastic fiber d. Cable including fiber core, the packet level and protection to three.

Optical fiber can be divided into single-mode optical fiber and multimode fiber. Single-mode optical fiber provide only a light path, processing complex, but has the greater communication capacity and further to the transmission distance. Multimode fiber DuoTiao use light path through the same signal transmission, the refraction of light to control the transmission speed.

And cable, optical cable compared with many of the advantages:

Transmission communication capacity, can achieve very high transmission rate;

The light signal transmission loss of far smaller than the electrical signals, can further distance transmission, suitable for long distance transmission;

The light signal almost from external interference of electromagnetic signal, and has a strong dv3000 battery resistance to ray electricity and anti-electromagnetism interference ability;

The light signal transmission in the fiber, almost nonexistent signal of the leak, good secrecy, information is not easy to be eavesdropping or intercept;

Fiber optic light weight, wiring easily;

The light signal transmission process is very low, ber transmission high reliability.

And cable, fiber optic cable connection at different ends of the need for electrical signals and light signal converter photoelectric conversion.

(4) wireless medium

Wireless media communication medium is a very important categories. Human beings use wireless as the communication medium of very long history, from the invention of the telegraph it started.

Wireless medium the biggest advantage is not to need to use a cable connection on both ends of the equipment, mobile flexible.

(5) infrared

Infrared almost is the earliest of the wireless medium into the computer. Infrared interface is a new generation of mobile phones with standard, it support cell phone and computer and other digital equipment according to the number communication. Infrared communication has low cost, easy to use and convenient connection, the characteristics of the structure tight gather together, so in small mobile equipment has been widely used. Through the red outside, all kinds of mobile equipment can interface free exchange data. Infrared wavelength is in 750 nm-1 the electromagnetic wave, it between nm the frequency of microwave and higher than the lower than visible light, and is a kind of the eyes of the one you can’t see the light. Due to the infrared wavelength is short, the obstacles to the diffraction ability is poor thing, so the more suitable for application in short-range wireless communication occasions need, point-to-point linear data transmission. Infrared data association will infrared data communication with the team, the range of wavelengths of light within 850 nm-within 900 nm. Equipped with infrared interface mobile phones wireless Internet access is very simple, need not connecting cables and PC CARD, as long as all Dell D630 battery set up infrared connection agreement can directly over the Internet. Infrared interface is orders in the world before range widely used a wireless connection technology, by many hardware and software platforms support; Through the data electrical impulses and infrared pulse the interaction between the turn in the wireless data transceiver to realize. Infrared interface features:

Used to replace point-to-point cable connection; New communication standard compatible early communication standard; Small Angle (30 degrees within the cone Angle), short, peer-to-peer linear data privacy is strong; the lose,

The transmission rate is higher, at present 4 M of the rate of FIR technology has been widely used, the rate of 16 M VFIR technology has been release. The main advantage of the infrared technology: make handset and computer can wireless transmission between data; Can also have the infrared interface in the exchange of information between devices; Infrared interface can save download or other information exchange the expenses; Due to the need for docking to transmit information, safety is stronger. Infrared technology faults:

In computer networks, the network card on one hand on the network to receive packets, solution after the bag, data through the motherboard bus transfers to local computer, on the other hand, the data on the local computer pack into network after. The network card in the computer has now become the standard configuration of one.

Small card, actually contains many secret? Let the door to watch. We are the most commonly used network equipment of network card when……. LAN (local area network card itself is network) equipment, through the gateway, routers equipment can hook up to the Internet this LAN, and the Internet itself is by innumerable such composed of local area network. In the local area network, the network card used for computer signals between the input and output, up to role on. When using the network card in the computer, put the expansion slots, according to support expansion slot form the main isa card, eisa card and apple MAC machine with ethercard, etc. Currently used more 16 isa card and 32 bit pci card.

Nic have their own interrupt and the I/O address, and their own cache, in order to store data. The network Lenovo U550 battery card, it will be said his job is normal or not.

The support of the network transmission rate is different, some for 10 MBPS per second, others for 100 MBPS per second. With 100 MBPS Ethernet technology popularization, the most current nets card has a 10 MBPS and 100 MBPS adaptive work model.

With remote start chip card, can be used in no disk workstation. No disk stand, no hard drive for work, can be no floppy disk. Through the nic starts computer, can protect the safety of the card system, avoid the virus. Additional, still can reduce cost.

In the notebook computer, the use of dexterity pcmcia card, used to exchange data with other computers, of course, make the notebook computer motherboard with a network card is the technology of the circuit, the mainstream.

Each card in a factory, are assigned a global addresses only logo, the logo was called network address, also known as the MAC address, physical address or hardware address. Network card by 48 bits of length address of a binary number. Among them, the first 24 bits said in after manufacturer, born for 24 bits assigned products manufacturer of serial number. If you use a hexadecimal number 12, says the six months hexadecimal number after manufacturers, said six hexadecimal number says the network card manufacturers the serial number of the product. Such as nic address-90- 99-27 11-CC:, which first six hex says the network card company production, by the corresponding intel-based network card serial number for 99-11-CC:. Network card is mainly used for the physical address equipment, and addressing behind this IP address is logical addressing role has cut the difference between very different.

There are many kinds of network card, according to the data link layer control to points have Ethernet card, token ring network card, ATM card, etc.; According to the physical layer to classification have wireless card, RJ-45 nets card, coaxial cable network card, light network card and so on. Their data link control, addressing, frame structure and so on the different; The physical connection of different ways, data coding, signal transmission medium, electricity equality is different.

The following main introduced us to the most common Ethernet network adapter. Ethernet using csma/CD (carrier protected reliably against detective multi-channel access] collision detection) control technology. He mainly defines the physical layer and the data link layer way of working. The data link layer and the physical realization of his function, since each other don’t care about each other how to operate. Between the two has a standard interface to transfer data and control.

Ethernet card of the physical layer can contain PA3450U-1BRS battery very DuoZhong technology, common are RJ45, light line, wireless, etc, the difference lies in the transmitting signals physical media and different medium. These are the 802 agreement in IEEE clan have detailed definition. This time we discussed the network card IEEE802.3 RJ45 belongs to the scope of the definition.

A piece of Ethernet network card (including the osi model’s system interconnection) two layers. The physical layer and the data link layer. The physical layer defines data to transmit and receive need electricity and optical signals, line state, clock benchmark, data coding and circuit, etc, and to the data link layer equipment to provide standard interface. The data link layer provides addressing institutions, data frame construction, and data error check, transmission control, to the network layer provides standard data by mouth etc. Function.

Ethernet card of the data link layer of the chip general Jane called MAC controller, the physical layer of the chip we Jane called phy. Many of the network card chip MAC and phy function did a chip, for example intel82559 nic and 3 com 3 C905 network adapter. But the MAC and phy mechanism or exist alone, just outside of the concept of the form is a single chip. Of course there is a lot of card MAC and phy do, such as separate d-link’s DFE-530 TX, etc.

Realize the data sending and receiving, frame encapsulation and unpacking, coding and decoding, medium access control etc. Function. The function of the physical layer of the OSI covered with the data link layer, so usually will network card to the data link layer of the equipment.

How to detect the network card in his machines? To windowsXP system for example:

Open the “control panel” of the “performance and maintenance”; Choose “check your basic computer information”, select “hardware”.

Click “device manager”, here is on your machine, all the hardware information

We have to check the information network, click Apple A1185 battery on the “network adapter,”

We can see that our network card is normal work, if the network card in the problem, and check the machine before see the work is normal or not, again another job.

(a) of a Modem

“Cat” here “cat” is the nickname “modem (); , of a modem is a modem, is a computer and telephone lines signal conversion between the device and the modulator and modem two parts, modulator computer is digital signal (such as the pieces etc) can be made in the telephone in the voice of the signal transmission device, the receiver, modem again voice signal conversion into computer able to receive digital signals. The role of the demodulation is using simulation signal transmission lines transmission digital signals. Electronic signal points two kinds, one kind is “analog signals”, was a “digital signal”. We use the telephone lines of transmission is analog signals, and transmitted between PC digital signals. Have to when you want to put himself through telephone lines of the computer connected to the Internet, you must use the system modem to “translate” two different signals. Connected to the Internet, when the PC to send information to the Internet, because the transmission line is analog signals, so must want to use a modem to the digital signal “translation” into analog signals can be transmitted to the Internet, and this process is called a “. When the PC to obtain information from the Internet, because from the Internet through telephone lines from information is to signal, so the PC want to read them, still must use a modem this “translation”, a process called “demodulation”. Add up to is “demodulation,” which is a modem the origin of the name.

Through a modem and telephone lines can realize the computer data between the letter, telephone line of analog signals turn digital signals to the computer, the computer simulation of the digital signal turn signals to telephone line. Due to the low frequency signals such as sound, transmission Lenovo U450P battery distance from very near, so need to take it to a high frequency signals loaded on to improve the transmission distance, this is a process of modulation. The high frequency signal as if the train, and the low-frequency signals than is good on the train. Modulation signal demodulation, also on the receiving end of the signal to choose our. This is called demodulation. What we call of a modem is just a modem, it is to accept data telephone line of analog signals turn digital signals to calculating machine, while sending data of computer digital signal turns the analog signals are sent to switch telephone line.

Modems generally divided into the outer type, built-in and PC KaShi 3 kinds. Can connect a telephone line or private network cable, external modem and computer serial interface; Built-in type modem directly interpolated in computer expansion slot; PC laptop computers used the KaShi is directly insert in the standard, in the pcmcia slot. At present a modem to basically have two kinds: built-in and outer type. 1. The built-in

Built-in modems in fact is a piece of the expansion of the computer, insert the card calculation of a machine expansion slot then it can be used, it need not take computer serial port. It is quite simple, the connection to the phone lines on the joint inserting the card “line” socket, card another interface “please”, and telephone connected, at ordinary times unused modems, telephone with a little affected.

2. The outer type

External modems is one on computer external cassette device, it need to take up the computer a serial port, also need to connect the power to work alone, external modems panel have the light a few state indicator light, can be easily you monitor the modem communication condition, and external modems installation and removal, set to buy and maintenance PA3420U-1BRS battery very convenient also, also easy to carry.

External modems connection very convenient also, its advantage is to a row of indicator light, you can directly see networking state, please pick up line and the method with built-in modulation is the same solution. But external modems have to have a root serial cable computer a serial port and modem serial port together, this serial line general with external modems distribution.

Modem is one of important performance parameters is the transmission rates, the present market condition 28.8 K, 33.6 K and a 56 K modem has, and 56 K modem has become the mainstream market products. But as the country’s limits, and communication lines with door too much, too little, because of the international export use at ordinary times it is difficult to reach the above rates, because of this, if you use the transmission rate per second show only a few K and even more low, you also don’t doubt computer or a modem have what problem.

To locate your computer installed in the modem type, please right click Windows desktop computer (I wish the computer) icon in the show, drop-down menu, select the properties (properties), and then click device manager (equipment management tag. In the equipment list double click of a modem (a modem), in the modem (a modem) small under the heading of modem shows that your name.

The network is with the invention of the computer and appear. Exactly is who invented the computer program, the americans and the British have Acer 5600 battery been arguing over: there is sufficient evidence can prove to be an Englishman invented first, but due to the needs of the confidential during world war two, so the British didn’t have publicly. Looks britons are too wronged, because the advent of the computer to the human shadow ring is too big, this kind of influence far beyond the motor, take credit written in American account, the English people of course were unfastened. But again, who let you confidential? Because the advent of the computer, make human computing power on a large scale improved. Because the early computer very expensive, and to the needs of the computing power and very urgent, people invented a way to use the computing power, this kind of method is called the points system.

What is a time-sharing system?

Time-sharing system allows users to monitor and keyboard contains only through the dumb terminals to make YongJi calculate machine "when the computer can also called a Host, Host >. Dumb terminals like PC, but does not have its own CPU, memory, and hard drive. By dumb terminals, hundreds of thousands of users can also visit host. Time-sharing system will be the host of time into piece, to the user when, users of distribution between in accordance with the time piece take turns using the computer. Time is very short, the user of will produce an illusion that you completely used for his host. And each user is used in that host, pay attention to a vocabulary to start in computer networks, frequently used the word "sharing (country) is".

This is the earliest prototype of the network, but, the modern network definition, not including the system when points.

As soon as possible in the first phase of the network and form: sharing host.

Integrated circuit and very large scale integrated HP NC6320 battery circuit, and finally promote the progress of the rapid development of the computer and quickly miniaturization. In the 1980 s, the United States IBM

(INternational) company get Machine invented the Personal computer (PC), Personal computers as a landmark progress. From the beginning of 1960 s, computers became a information and data processing of the main equipment, people found that need to deal with each computer data exchange in order to improve the treatment efficiency of the system. Boxing network appeared second phase and form: share data. If we say that the true sense of the computer is the 1940 s saw the emergence of words, so the true sense of the computer network appeared in the 1960 s. In human history of the development of the computer program, the emergence of the network is not late. We are now enjoying the height of the development of network environment, through the same short but rich process.

We used to have a simple premise: if all of the network, not a big pack people our computer, then come, study the decomposition of the smaller the points. For example, we extracts a small part of the network, contains 1000 node, then calculate any two nodes interval. Next we again in this foundation I selected the greater part, contains 10000 node, then calculate this part of any two nodes in the interval. We repeatedly select, repeated calculation, until I have computer system can handle the limit, and then analyses the change of interval tending to the node potential-results show that the increase of the node interval than the increase of the number of node much more slowly, and follow the cycle of simple and the formula. (1) the results that we know that the HP 541 battery total number of a web document, can is expected to the whole network of node interval. Japan electric company provides web document data of the total. They estimated that by the end of 1998, the network Bi public indexing of the node for a total of 800 million a node. In doing so, according to the formula, I can be calculated network "diameter is 18.59," for 19 approximation. Modeled on the statement, axel 19 degrees is the interval. Although the actual browsing wait when, some people got the impression can be observed, but is certainly a network little world, between any two documents the average interval for 19.

The rice belgravia liam six degrees of separation and the world wide web of 19 degrees space combination up, in the network, there is something beyond the wishes of human more basic things, decided the links in the distribution network. This kind of speculation and for subsequent discoveries confirmed. Scientists found in all human studies in the network, the interval are small. In fact, what the food chain, and the interval between species only two links; The cells of the gap between the son points is 3 times chemical reaction; The scientific community, the different areas of the common the interval between published works is four to six links; Nematode (big enough like between nerve cells in the brain which 14 neural key links. In fact, the world wide web of 19 degrees interval is the biggest, so far, the other research network the Spaces between the two to 14.

19 degrees interval and the difference between the six degrees space not small indeed. However, this is not a problem. The point is that the large network, although often have 1 million or billions of node, but it is a small world, the gap between the nodes than the total number of nodes are much smaller. Our society has 6 billion node, the interval of about 6. The world wide web has close to 1 billion node, the interval for 19. And by thousands of router consists of the Internet, the interval of 10. From this Angle consider problem, interval is a 6 or 19, the difference is negligible.

People naturally will asked the questions is: why large network nodes in the interval of so little? With billions of node of the network, and how to an organic whole repeatedly, to make the gap between the node so little? The answer is that these networks are highly photograph associated characteristics. Each other In front of the chapter, we talked about random network just each node a link node can be composed string. The problem is, if the node number is more than 1, link and how? In the real network, each node has generally more than 1 of the connection. When the network links to the average 1 threshold section node and the gap between the point is very large. But with the increase of the link, the distance between the nodes dramatically smaller. Let us consider the average link node of 4 for network. This means that from a typical node, walk the one step can achieve a node of the one. But, in fact, between the two power network links the number of node force, company for a link node number for "a. Therefore, if the value is bigger, so and even 4 is very small, households, some double Only ill need-1 step, can achieve all can find node. That would explain why Lenovo SL510 battery the interval of the most network so small.

Here the analysis can easily be used to express mathematical functions formula. This formula can be used to predict the interval of the random network nodes. (13 network nodes in small, the interval because of the numerical formula of small. In fact, even if the original numerical again big, the logarithm was very small. For example, with 10 at the bottom of the logarithm of million is only 9. For example, if there are two network, their nodes of steel mill links are 10, but one of the scale of the network is another 100 times, so, the bigger the quarter point interval network only small space of the network 2. Logarithmic relationship makes huge network becomes around us, caused a and a network of small world. ?

In among peers, Karen, the most famous is the pure, he often forget to mention for good before meeting forgotten it. Karen, a close friend of the opponent’s g and Robert frost LanXi (milk with such as six) once said: "I have to run home, because force Karen, promised to come to my house, and probably because he put it to forget, 0 and really will come." Six degrees have much space, Karen style: first was people forget ‘and then left again was found by the mass media and the scientific community, the attention. I don’t know

? Eight (1) if the number of nodes in the network for the value of the han, not greater than condition. So according 4 formula, it can well predict the random network average way exactly is who first proposed the concept of space six degrees, I know the earliest related narrative, from Karen. But he is come from where? Is he thought up for themselves? Considering that he have no enemy’s wit, and the west can he want to others not thought, others see not seen character, he can come up with this fall is easy to understand. To no, he or from cafe to listen to that, as he wrote short little said of performance like that? I’m afraid we never get a definite answer. But according to the subsequent events that change is something fun.

Karen, short novel, published in 1929. At that time the proms live in cloth Budapest, were 17. Because the book, even if, Karen is a failure, will serve a move, so the proms is likely to read or heard of this article, Karen little said, access to his proposed between people on the planet can by the five acquaintances mutual league tied point of view. For Alfred ‘riley we also can do a similar measure push. The novel appeared, although he was nine years old, but to literature.

The so-called six degrees intervals and 19 degrees interval but has a powerful said misleading, because for people may role assumed that in a small world, it is easy to find the necessary east west "the truth is not so This is not only because we want to find people or document in six or 19 link, and because of all about people or document in six or 19 links away. In other words, 6 or and when may be a decimal, also may be a larger, it depends on what you’re looking for. Since each page have an average of seven or so links, this means that the first document from the start, there are seven link, point hit twice, after 49 document waiting for 343, and then click on the document to # analogy. That way, if you wish to reach the node, step away 19 in principle we should and Chad 10 16 sc, this document than the total number of network documents more than ten thousand times a d-it seems to be contradictory, but not actually in the process of the search: we met in some of the link will lead us to fall back. Therefore, they are not "new" links. But, even if it is per click a document just for a second, and to try to finish all the documents about 19 step, also want to 300 million years! Even so, although however have so many choices, even if is not the use of the search engine, we sometimes still ran quickly find what they need to document.

Of course, the secret is that we do not blindly follow sb click on all the chain answered. We can use tip information judgment. For example, in the search for Picasso’s information is shut, if web site have three options, we will choose of modern art in the link, not point at wrestling players or the frog prince love life links. Through the interpretation of the link, we do not need to check the meaning of 19 degrees within some pages, it only takes a few clicks can find the required page. Although this way seems to be the most efficient, but in fact, the use of this method is not always able to find the shortest path. For example, we have ignored on the road of the wrestlers of web pages is probably just just have to Picasso web link, there was always the possibility. But most people in search of Picasso’s number of time, can ignore wrestlers of links, lead to finally take a few detour. By contrast, the computer has no personal taste or be fond of, it will one by one to check all the links Chad. Through all the possible paths for Chad, computer will eventually will find the shortest path.

Through the network of Picasso in seven looking for information, highlight six degrees of separation reflects a fundamental question: m to belgravia lime overestimating the United States any the shortest distance between two people. Six degrees space actually can only be upper limit. In any two Dell 1520 battery people between the existing, there are innumerable length different paths. M the experimental subjects belgravia lime doesn’t know to contact target’s shortest path. It was like in the maze, all we can see is the corridor and the gate. Eyes Even if have guide needles, and to know that export is substantially in the north, want to find the exit also will spend a lot of time, but also our action efficiency will be also very low. If, on the other hand, have fan site, not out of that time and 5 minutes, we can go out. Similarly, if the mill; The object’s silk experiment have all the United States all social road map, then letters also can pass Omaha and Boston to each other of the shortest path between the hands. No road map in hand, according to participants can only guess, sent a letter to the most likely will be sent to 6 of the object it into. Cases of female , if you want to meet the President, the first thought of the country may be those who know the President. You may want to most of the state’s is the senator or representative. Since most people are in fact and senator and selfless hand in, we first will try to find people who knew him, let the person which, to introduce me to senator and the President. So it need at least three among people. At this time, you may not think a few days ago, the ? time dinner party, sit by the person who probably time to go to school and his excellency President are classmates. So, you actually and President of the interval between two only. Similarly, meters of lime belgravia experiment of almost without exception record path is the shortest path. Therefore, really are social space is obviously overrated. The actual value must be less than 6, may also lower than estimated 5, Karen. Because there is no "social search engine", I may never make it clear the actual value.

Six degrees space to modern society is the result of this is due to a human always have to pay. At the same time human new invention of long-distance communication means a push it? Bad role. Lie prone skin We live of the global village for humans is actually born phenomenon. The ancestors of most americans are the homeland and family life is lost in the Midwest prairie, or the Rocky Mountains gold mine in the American people can’t and oceans apart continent of Europe to keep alliance, the relatives. When neither of opening, also couldn’t phone, the contemporary social network to be fragile, once because people move elsewhere and rupture, it is difficult to even. In the 20 century, as the mail system, telephone and air travel to eliminate and shorten the distance between people and people, all this changed. Now, to the United States and hence can continue to keep in touch with friends and family. We can also do keep in touch. For example I personally, although some relatives and friends live in South Korea or eastern Europe, but I can still and they keep in touch. In the twentieth century, the world has irreversibly collapse for a small world. And our world now are going through another critical poly ( states such as), the Internet is to every corner of the world is an organic whole repeatedly. Although in the network, and any one person for 19 times the distance between the click, but and relatives and friends, but only between the one click. Since after break up, some friends may have changed the five job, changed 3 cities, but no matter where they went, only to we like, we can all on the Internet to find their footprint. The world has been shrinking, this is because of the likely to be completely disconnect before social link, now but can easily keep going. And man can keep the number of links to the society also increased significantly, the further reducing the social interval. M belgravia liam estimates for the 6 degrees; Karen, estimates for the 5 degrees; Now, this value is likely to reduce to three.

"Small world" is really all network has a genetic attributes. The smaller interval and not mysteries of human society, or special properties, in fact, most of the network all around us with this feature. This feature is rooted in the structure of the network of web page or friends, both find the link is not among the facts. The formation of small world, and we are familiar with the OuJiLiDe geometry description of the world seems to exist in a much different. In OuJiLiDe world, distance is calculated mileage. But human communication, more and more and physical distance irrelevant. People in the world travel, rising from the crowd of completely alien to find old acquaintance, such examples show that we and the earth again and again on the other side of the one person, the relationship between the AiMen neighbors than and may even close relationship. In the nets not OuJiLiDe world each @ roaming, we continue to feel the universe exists between a kind of new geometry and wait for our research, so that we can understand that master side complex world.

That is the purpose of pranksters mischief. Historically, many of the relevant security incident is out of sheer gag purpose and happen.

The damage caused by the pranksters is to make you lose your sense of security, worry about system be attacked or information is stealing.

1. The second threat: the Internet fraud

Use the Internet to cheat behavior more and more, the way is DuoZhong varied. Mutual networking and did not give us provide a mechanism, to ensure that the only good people can surf the Internet.

The main way of network cheating is to use the Internet to releasing false Apple A1080 battery information, and thus take interest or to the other purposes. This kind of behavior although do not have more technical characteristics, but have the typical information against characteristics.

In October 2006, the Spanish police arrested a by five Nigerian, and a British, a Spanish and unknown nationality figure composed of mail fraud gangs. The gang for fraud means is very simple, is to use the Internet to send large amount of E-mail. In the email, the cheats says someone in Spain’s insurance library mediator entities tens of millions of dollars, but need someone to help to get the money. The condition is to help people can find of commission, take the money and a pay. From the United States, France, Germany, Spain, and other countries of more than 300 DuoRen to cheat a total of 19.8 million euros.

To Lou this behavior, a new produce term, listed by Fishing, please and combination to use network, used to show the fraud, Chinese meaning think is “Phishing”.

At present, all kinds of network fraudulent activities has become the network is a wide range of information threat.

“Phishing” use E-mail and Web site forge information, make the patsy fraud initiative leak her financial data, such as credit card Numbers, user name and password and account of social security Numbers, etc.

Information in network will themselves as impostors ChengYinHang, retailers, information service contractor and the credit card company and so Dell M1330 battery on, all of the information to contact with these users, there are some will respond.

At present, some common phishing attack means are:

(1) using the Internet, participate in the auction the auctioneer, the payment for goods, not

(2) through the email false information deceived users;

(3) and online banking, securities registration and famous website similar domain name, deceive with door, retrieve the user information or provide false service:

(4) to false electronic business transactions, the use of famous e-commerce platform, ? for fraud;

(5) use E-mail to entice users to transfer the false information users, through the special script code and hyperlink users click malicious website, fishing, obtain the users’ interest; letter

(6) use Trojan and hackers steal users | & technology, through E-mail or nets: station to send or hidden trojans, through the trojans intercept the user information;

(7) use the user password etc holes that weak cracked user accounts and passwords;

(8) use mobile phone short message for fraud, through the special equipment or illegal mobile operators get the phone number, send text messages, deceive this kind of means can use Internet nets establish SMS platform.

3. The third threat: information ^ immature artists imitate

Use the network to steal information many methods, as described above, trojans, network sniffing and information intercepted is a common information theft means. Information is the essential purpose of immature artists imitate using information obtain interest. This is a 2002 years of news.

The fbi in New York destroyed a special stolen credit card information I make the sin, and arrested involving the gang of three suspects.

The gang leader proficient in computer, the first time the chance, he won in the Internet got an American credit card number, then put the number to $30 for the price of a friend.

Thus began his taste good, colluding with two other people, beginning a crazy action, using the Internet to steal the has more than 30000 americans on a credit card information, and then to each credit card information $60 price sell out. Their move to make it more than 30000 victims lost total more than $2.7 million in funds. 4. The fourth threat: information against

In September 2000, Israeli prime minister ariel Sharon led into the police in the Jerusalem temple hill islamic shrines al-aqsa mosque, leading to a new round of israeli-palestinian violence, and at the same time and on the Internet to hackers on the meeting the fierce. By the end of 2000, a total of two hundred DuoGe relevant web site with Israel, the Palestinian attack website for more than 30 house. This is typical of WangLaoZhan form, but also just folk outbursts. In fact, information warfare have been rose to the level of HP Compaq 6535s battery the national strategy. To us, from the west have system information penetration is of the biggest threat.

March 24, 2003, the United States and Iraq’s second gulf war started. The war started in the United States on the surface of the bombing, but in fact already on the Internet. American intelligence agencies to Iraq in pre-war sent a E-mail, lists the Iraqi President saddam hussein’s various “crime” contained, work; At the same time, from the world of computer to American government and military site launched attacks.

Maybe for ordinary people speaking, seems to information warfare is still, but, as the most quickly on the Internet by the information dissemination platform on the network, each computer things are in fact penetration and the object of information publicity.

In December 1996, the United States defense department announced the secret instructions “information” to fight the concept of “instead of” information warfare.

According to the American people, the definition of information refers to “in the fight against any time, in order to influence the enemy’s information and information system while protection to my side of the information and information system of all kinds of action taken,” and that “information warfare is in crisis or conflict, in order to achieve or teams during a certain targets, according to one or DuoGe specific enemy of information against”.

From two definition, can see, americans in its secret instructions to the category of information warfare in the manner and the big expansion. This, not only to the United States, but also to the future of the world of information security development, will have far-reaching influence.

“Information against” concept of the information war that the United States is complete ascension to strategic level, emphasize more make full use of “the media war”, “psychologicial warfare”, “WangLaoZhan,” and so on, control the media and means of information network, penetration and deterrence, thus seek war slightly and tactical interests.