计算机网络英文文献
计算机网络英文资料
NetworkThe Internet is a worldwide, publicly accessible series of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as electronic mail, online chat, file transfer, and the interlinked web pages a nd other resources of the World Wide Web (WWW).The Internet and the World Wide Web are not one and the same. The Internet is a collection of interconnected computer networks, linked by copper wires, fiber-optic cables, wireless connections, etc. In contrast, the Web is a collection of interconnected documents and other resources, linked by hyperlinks and URLs. The World Wide Web is one of the services accessible via the Internet, along with various others including e-mail, file sharing, online gaming and others described below. However, "the Internet" and "the Web" are commonly used interchangeably in non-technical settings.Computer NetworkA computer network is an interconnected group of computers. Networks may be classified by the network layer at which they operate according to basic reference models considered as standards in the industry, such as the five-layer Internet Protocol Suite model. While the seven-layer Open Systems Interconnection (OSI) reference model is better known in academia, the majority of networks use the Internet Protocol Suite (IP).In computer science, a data structure is a way of storing data in a computer so that it can be used efficiently. Often a carefully chosen data structure will allow the most efficient algorithm to be used. The choice of the data structure often begins from the choice of an abstract data type. A well-designed data structure allows a variety of critical operations to be performed, using as few resources, both execution time and memory space, as possible. Data structures are implemented by a programming language as data types and the references and operations they provide.Different kinds of data structures are suited to different kinds of applications, and some are highly specialized to certain tasks. For example, B-trees are particularly well-suited for implementation of databases, while networks of machines rely on routing tables to function.In the design of many types of programs, the choice of data structuresis a primary design consideration, as experience in building large systems has shown that the difficulty of implementation and the quality and performance of the final result depends heavily on choosing the best data structure. After the data structures are chosen, the algorithms to be used often become relatively obvious. Sometimes things work in the opposite direction - data structures are chosen because certain key tasks have algorithms that work best with particular data structures. In either case, the choice of appropriate data structures is crucial.This insight has given rise to many formalised design methods and programming languages in which data structures, rather than algorithms, are the key organising factor. Most languages feature some sort of module system, allowing data structures to be safely reused in different applications by hiding their verified implementation details behind controlled interfaces. Object-oriented programming languages such as C++ and Java in particular use classes for this purpose.Since data structures are so crucial, many of them are included in standard libraries of modern programming languages and environments, such as C++'s Standard T emplate Library containers, the Java Collections Framework, and the Microsoft .NET Framework.The fundamental building blocks of most data structures are arrays, records, discriminated unions, and references. For example, the nullable reference, a reference which can be null, is a combination of references and discriminated unions, and the simplest linked data structure, the linked list, is built from records and nullable references.Data structures represent implementations or interfaces: A data structure can be viewed as an interface between two functions or as an implementation of methods to access storage that is organized according to the associated data type.Binary treeIP stack connectionsUDP encapsulation。
计算机网络英语作文
计算机网络英语作文Title: The Importance of Computer Networks in Today's World。
In today's interconnected world, computer networks play a crucial role in facilitating communication, sharing resources, and enabling collaboration on a global scale. From personal communication to large-scale businesses and government operations, computer networks have become an integral part of our daily lives. In this essay, we will delve into the significance of computer networks and explore how they have revolutionized various aspects of our society.First and foremost, computer networks have transformed the way we communicate. Through the internet, individuals can connect with each other regardless of geographical barriers. Email, instant messaging, social media platforms, and video conferencing tools have become indispensable means of communication in both personal and professionalsettings. This seamless exchange of information has greatly enhanced productivity and efficiency in various sectors.Moreover, computer networks facilitate the sharing and dissemination of information on a massive scale. Online platforms enable users to access vast repositories of knowledge, ranging from educational resources to entertainment content. The proliferation of online libraries, digital archives, and streaming services has democratized access to information, empowering individuals to learn and grow irrespective of their location or socioeconomic status.Furthermore, computer networks have revolutionized the way businesses operate. Through e-commerce platforms, companies can reach a global audience and conduct transactions seamlessly. Supply chain management systems rely on computer networks to coordinate the flow of goods and services efficiently. Moreover, cloud computing services offer businesses scalable and cost-effective solutions for storage, data processing, and software deployment. These technological advancements have not onlyimproved operational efficiency but also fostered innovation and entrepreneurship.In addition to enhancing communication and collaboration, computer networks play a crucial role in ensuring the security and integrity of data. With the proliferation of cyber threats, securing network infrastructure and safeguarding sensitive information have become paramount concerns for organizations and individuals alike. Encryption technologies, firewalls, and intrusion detection systems help mitigate risks and protect against unauthorized access and malicious activities. Moreover, ongoing research and development efforts are focused on enhancing cybersecurity measures to address emerging threats and vulnerabilities.Furthermore, computer networks have transformed the way we access and consume entertainment and media content. Streaming services, online gaming platforms, and social media networks have become ubiquitous forms of entertainment, offering users a diverse array of content at their fingertips. The advent of high-speed internetconnectivity has enabled seamless multimedia streaming, immersive gaming experiences, and real-time interaction with content creators and fellow users.Additionally, computer networks have revolutionized the field of healthcare by enabling telemedicine and remote patient monitoring. Patients can consult healthcare professionals, access medical records, and receive diagnoses and treatment recommendations remotely, eliminating the need for physical visits to healthcare facilities. This not only improves access to healthcare services, particularly in underserved areas, but also enhances patient convenience and reduces healthcare costs.In conclusion, computer networks have transformed the way we communicate, collaborate, conduct business, and access information and entertainment. From personal interactions to global transactions, computer networks have become the backbone of our interconnected world. However, it is essential to recognize the importance of ensuring the security and integrity of these networks to mitigate risks and safeguard against cyber threats. As technologycontinues to evolve, computer networks will undoubtedly play an even more significant role in shaping the future of our society.。
计算机网络安全论文参考文献
计算机网络安全论文参考文献以下是一篇关于计算机网络安全的论文参考文献：[1] Stallings, W. (2013). Network security essentials: Applications and standards (Vol. 1). Pearson.这本书探讨了计算机网络安全的基本概念、原理和技术。
它提供了对各种网络安全协议、算法和策略的详细介绍，以及实际应用和标准的示例。
[2] Kurose, J. F., & Ross, K. W. (2010). Computer networking: a top-down approach. Pearson Education.这本书是计算机网络的经典教材，它详细介绍了计算机网络体系结构和协议的工作原理。
它还包括网络安全的基本原理和技术，如加密、身份验证和访问控制。
[3] Anderson, R. (2008). Security engineering: a guide to building dependable distributed systems. John Wiley & Sons.这本书通过分析实际系统的安全问题和解决方案，提供了构建安全分布式系统的指南。
它涵盖了许多关键安全概念和技术，如访问控制、防火墙、入侵检测和身份管理。
[4] Pfleeger, C. P., & Pfleeger, S. L. (2007). Security in computing. Prentice Hall.该书介绍了计算机安全的基本概念、原理和技术，如密码学、访问控制、网络安全和软件安全。
它还提供了关于安全策略和风险管理的实际指南。
[5] Schneier, B. (2015). Applied cryptography: protocols,algorithms, and source code in C. John Wiley & Sons.这本书是密码学的经典教材，它详细介绍了密码学的基本概念、原理和算法。
外文文献—计算机网络
英文原文：Computer networkA computer network, often simply referred to as a network, is a collection of computers and devices interconnected by communications channels that facilitate communications among users and allows users to share resources. Networks may be classified according to a wide variety of characteristics. A computer network allows sharing of resources and information among interconnected devices.History ：Early networks of communicating computers included the military radar system Semi-Automatic Ground Environment (SAGE) and its relative the commercial airline reservation system Semi-Automatic Business Research Environment (SABRE),started in the late 1950s.[1][2]When Russia launched His SPUTNIK Satellite in Space In 1957.The American Started Agency Names ADV ANCE RESEARCH PROJECT AGENCY (ARPA) & launched THis 1st Satellite Within 18 Month After Establishment.Then Sharing Of TheInformation InAnother Computer They Use ARPANET.And This All Responsibility On America's Dr.LIED LIEDER.Then in 1969,ARPANET Comes in INDIA And INDIAN Switched This Name To NETWORK. In the 1960s, the Advanced Research Projects Agency (ARPA) started funding the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense. Development of the network began in 1969, based on designs developed during the1960s.[3] The ARPANET evolved into the modern Internet.Purpose ：Computer networks can be used for a variety of purposes: Facilitating communications. Using a network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.Sharing hardware.：In a networked environment, each computer on a network may access and use hardware resources on the network, such as printing a document on a shared network printer.Sharing files, data, and information. In a network environment, authorized user may access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks.Sharing software.：Users connected to a network may run application programs on remote computers.information preservationSecurityNetwork classification The following list presents categories used for classifying networks.Connection method ：Computer networks can be classified according to thehardware and software technology that is used to interconnect the individual devices in the network, such as optical fiber, Ethernet, wireless LAN, HomePNA, power line communication or G.hn.Ethernet as it is defined by IEEE 802 utilizes various standards and mediums that enable communication between devices. Frequently deployed devices include hubs, switches, bridges, or routers. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium. ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network.Wired technologies ：Twisted pair wire is the most widely used medium for telecommunication.Twisted-pair cabling consist of copper wires that are twisted into pairs. Ordinary telephone wires consist of two insulated copper wires twisted into pairs. Computer networking cabling consist of 4 pairs of copper cabling that can be utilized for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second. Twisted pair cabling comes in two forms which are Unshielded Twisted Pair (UTP) and Shielded twisted-pair (STP) which are rated in categories which are manufactured in different increments for various scenarios.Coaxial cable is widely used for cable television systems, office buildings, and other work-sites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmissionspeed range from 200 million to more than 500 million bits per second.Optical fiber cable consists of one or more filaments of glass fiber wrapped in protective layers. It transmits light which can travel over extended distances.Fiber-optic cables are not affected by electromagnetic radiation. Transmission speedmay reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster than atwisted-pair wire.[citation needed]Wireless technologies ：Terrestrial microwave – Terrestrial microwaves use Earth-based transmitter and receiver. The equipment looks similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx, 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.Communications satellites –The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earth-orbiting systems are capable of receiving and relayingvoice, data, and TV signals.Cellular and PCS systems – Use several radio communications technologies. The systems are divided to different geographic areas. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area.Wireless LANs –Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. An example of open-standards wireless radio-wave technology is IEEE.Infrared communication , which can transmit signals between devices within small distances not more than 10 meters peer to peer or ( face to face ) without any body in the line of transmitting.Scale：Networks are often classified as local area network (LAN), wide area network (WAN), metropolitan area network (MAN), personal area network (PAN), virtual private network (VPN), campus area network (CAN), storage area network (SAN), and others, depending on their scale, scope and purpose, e.g., controller area network (CAN) usage, trust level, and access right often differ between these types of networks. LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations, such as a building, while WANs may connect physically separate parts of an organization and may include connections to third parties.Functional relationship (network architecture) ：Computer networks may be classified according to the functional relationships which exist amongthe elements of the network,e.g., active networking, client–server, Wireless ad hoc network andpeer-to-peer (workgroup) architecture.Network topology ：Main article: Network topology Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network.Network topology is the coordination by which devices in the network are arranged in their logical relations to one another, independent of physical arrangement. Even if networked computers are physically placed in a linear arrangement and are connected to a hub, the network has a star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks.Types of networks based on physical scopeCommon types of computer networks may be identified by their scale.Local area network：A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernettechnology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines).[4]Typical library network, in a branching tree topology and controlled access to resources All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router thatconnects to the Internet and academic networks' customer access routers.The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s.[5]Personal area network :A personal area network (PAN) is a computer network used for communication among computer and different information technological devices close to one person. Some examples of devices that are used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. A PAN may include wired and wireless devices. The reach of a PAN typically extends to 10 meters.[6] A wired PAN is usually constructed with USB and Firewire connections while technologies such as Bluetooth and infrared communication typically form a wireless PAN.Home area network :A home area network (HAN) is a residential LAN which is used for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices. An important function is the sharing of Internet access, often a broadband service through a CATV or Digital Subscriber Line (DSL) provider. It can also be referred to as an office area network (OAN).Wide area network :A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.Campus network :A campus network is a computer network made up of an interconnection of local area networks (LAN's) within a limited geographical area. The networkingequipments (switches, routers) and transmission media (optical fiber, copper plant, Cat5 cabling are almost entirely owned (by the campus tenant / owner: an enterprise, university, government etc.).In the case of a university campus-based campus network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls.Metropolitan area network:A Metropolitan area network is a large computer network that usually spans a city or alarge campus. Sample EPN made of Frame relay WAN connections and dialup remote access.Enterprise private network :An enterprise private network is a network build by an enterprise to interconnect various company sites, e.g., production sites, head offices, remote offices, shops, in order to share computer resources.Virtual private network :A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The data link layer protocols of the virtual network are said to be tunneled through thelarger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features.VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point.Internetwork :An internetwork is the connection of two or more private computer networks via a common routing technology (OSI Layer 3) using routers. The Internet is an aggregation of many internetworks, hence its name was shortened to Internet.Backbone network :A Backbone network (BBN) A backbone network or network backbone is part of a computer network infrastructure that interconnects various pieces of network, providing a path for the exchange of information between different LANs or subnetworks.[1][2] A backbone can tie together diverse networks in the same building, in different buildings in a campus environment, or over wide areas. Normally, the backbone's capacity is greater than the networks connected to it.A large corporation that has many locations may have a backbone network that ties all of the locations together, for example, if a server cluster needs to be accessed by different departments of a company that are located at different geographical locations.The pieces of the network connections (for example: ethernet, wireless) that bring these departments together is often mentioned as network backbone. Networkcongestion is often taken into consideration while designing backbones. Backbone networks should not be confused with the Internet backbone.Global area network:A global area network (GAN) is a network used for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas, etc. The key challenge in mobile communications is handing off the user communications from one local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial wireless LANs.[7]Internet :The Internet is a global system of interconnected governmental, academic, corporate, public, and private computer networks. It is based on the networking technologies of the Internet Protocol Suite. It is the successor of the Advanced Research ProjectsAgency Network (ARPANET) developed by DARPA of the United States Department of Defense. The Internet is also the communications backbone underlying the World Wide Web (WWW).Intranets and extranets :Intranets and extranets are parts or extensions of a computer network, usually a local area network. An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users. Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information.An extranet is a network that is limited in scope to a single organization or entity and also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities—a company's customers may be given access to some part of its intranet—while at the same time the customers may not be considered trusted from a security standpoint. Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although an extranet cannot consist of a single LAN; it must have at least one connection with an external network.Overlay network:An overlay network is a virtual computer network that is built on top of another network. Nodes in the overlay are connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network.中文译文：计算机网络计算机网络，通常简单的被称作是一种网络，是一家集电脑和设备为一体的沟通渠道，便于用户之间的沟通交流和资源共享。
计算机网络(第四版)英文原版1.9 Summary
A factor in the delay of a store-and-forward packet-switching system is how long it takes to store and forward a packet through a switch. If switching time is 10 μsec, is this likely to be a major factor in the response of a client-server system where the client is in New York and the server is in California? Assume the propagation speed in copper and fiber to be 2/3 the speed of light in vacuum.
Well-known networks include the Internet, ATM networks, Ethernet, and the IEEE 802.11 wireless LAN. The Internet evolved from the ARPANET, to which other networks were added to form an internetwork. The present Internet is actually a collection of many thousands of networks, rather than a single network. What characterizes it is the use of the TCP/IP protocol stack throughout. ATM is widely used inside the telephone system for long-haul data traffic. Ethernet is the most popular LAN and is present in most large companies and universities. Finally, wireless LANs at surprisingly high speeds (up to 54 Mbps) are beginning to be widely deployed.
有关计算机网络的英文作文
有关计算机网络的英文作文Computer Networks: The Foundation of Modern Communication.In the digital landscape of the 21st century, computer networks have become an indispensable part of our lives. They connect countless devices, facilitating seamless communication, data sharing, and access to a vast array of information and resources. Understanding the fundamentals of computer networks is crucial for navigating this interconnected world.Definition and Components.A computer network is a collection of interconnected computers that can communicate with each other and share resources. These networks can vary in size, from small home networks connecting a few devices to massive global networks connecting millions of computers.Essential components of a computer network include:Network Interface Card (NIC): A device in each computer that enables it to connect to the network.Transmission Medium: The physical infrastructure, such as cables, wires, or wireless signals, that transmits data between devices.Network Protocols: Rules that govern data transmission, ensuring compatibility and communication among devices.Network Operating System (NOS): Software that manages the network's resources and ensures its smooth operation.Types of Computer Networks.Numerous types of computer networks exist, eachtailored to specific purposes:Local Area Networks (LANs): Connect devices within a limited geographic area, such as a building or campus.Wide Area Networks (WANs): Connect devices over a broader geographic area, such as between cities or countries.Metropolitan Area Networks (MANs): Connect devices within a metropolitan area, typically spanning a city or region.Global Area Networks (GANs): Connect devices worldwide, providing global connectivity.Wireless Networks: Connect devices without the use of physical cables, often using radio frequencies or Wi-Fi.Network Topologies.The arrangement of devices within a network is known as its topology. Common topologies include:Bus: A single communication channel that all devices connect to.Ring: A circular structure where each device connects to two others.Star: A central hub connects to all devices.Mesh: A redundant structure where each device connects to multiple others.Network Protocols.Protocols are essential for ensuring communication and interoperability among devices on a network. Some key protocols include:Transmission Control Protocol (TCP): A reliable protocol for transmitting data across the Internet.Internet Protocol (IP): The addressing scheme for devices on the Internet.Hypertext Transfer Protocol (HTTP): The protocol usedfor web browsing.File Transfer Protocol (FTP): The protocol for file transfer between computers.Domain Name System (DNS): The service that translates domain names into IP addresses.Network Security.Protecting computer networks from unauthorized access, threats, and vulnerabilities is paramount. Network security measures include:Firewalls: Software or hardware that monitors and controls network traffic.Intrusion Detection Systems (IDSs): Devices that detect and report suspicious network activity.Virtual Private Networks (VPNs): Secure connections that allow remote users to access private networks.Encryption: Converting data into a secure format to prevent unauthorized access.Applications and Benefits of Computer Networks.Computer networks have revolutionized communication and data sharing:Access to Information: Networks provide access to a vast repository of information and resources on the Internet.Communication: Networks facilitate real-time communication through email, instant messaging, and video conferencing.Collaboration: Networks enable collaboration between remote teams and individuals through shared documents, video meetings, and project management tools.Entertainment: Networks provide access to onlinegaming, streaming services, and social media platforms.E-Commerce: Networks enable online shopping and banking, expanding business opportunities and consumer choices.Conclusion.Computer networks are the backbone of modern communication and information exchange. They have transformed the way we live, work, and interact with each other. Understanding the fundamentals of computer networks is essential for navigating the digital landscape and leveraging its immense benefits. As technology continues to evolve, networks will play an increasingly crucial role in shaping our connected world.。
计算机网络 外文文献 外文翻译 英文文献 新技术的计算机网络
文献来源：/Freepaper/Jisuanji/wangluo/200810/28156.html一、原文New technique of the computer networkAbstractThe 21 century is an ages of the information economy, being the computer network technique of representative techniques this ages, will be at very fast speed develop soon in continuously creatively, and will go deep into the people's work, life and study. Therefore, control this technique and then seem to be more to deliver the importance. Now I mainly introduce the new technique of a few networks in actuality live of application.keywordsInternet Digital Certificates Digital Wallets Grid Storage1. ForewordInternet turns 36, still a work in progressThirty-six years after computer scientists at UCLA linked two bulky computers using a 15-foot gray cable, testing a new way for exchanging data over networks, what would ultimately become the Internet remains a work in progress.University researchers are experimenting with ways to increase its capacity and speed. Programmers are trying to imbue Web pages with intelligence. And work is underway to re-engineer the network to reduce Spam (junk mail) and security troubles.All the while threats loom: Critics warn that commercial, legal and political pressures could hinder the types of innovations that made the Internet what it is today.Stephen Crocker and Vinton Cerf were among the graduate students who joined UCLA professor Len Klein rock in an engineering lab on Sept. 2, 1969, as bits of meaningless test data flowed silently between the two computers. By January, three other "nodes" joined the fledgling network.Then came e-mail a few years later, a core communications protocol called TCP/IP in the late 70s, the domain name system in the 80s and the World Wide Web - now thesecond most popular application behind e-mail - in 1990. The Internet expanded beyond its initial military and educational domain into businesses and homes around the world.Today, Crocker continues work on the Internet, designing better tools for collaboration. And as security chairman for the Internet's key oversight body, he is trying to defend the core addressing system from outside threats.He acknowledges the Internet he helped build is far from finished, and changes are in store to meet growing demands for multimedia. Network providers now make only "best efforts" at delivering data packets, and Crocker said better guarantees are needed to prevent the skips and stutters now common with video.Cerf, now at MCI Inc., said he wished he could have designed the Internet with security built-in. Microsoft Corp.Yahoo Inc. and America Online Inc., among others, are currently trying to retrofit the network so e-mail senders can be authenticated - a way to cut down on junk messages sent using spoofed addresses.Many features being developed today wouldn't have been possible at birth given the slower computing speeds and narrower Internet pipes, or bandwidth, Cerf said.2.Digital CertificatesDigital certificates are data files used to establish the identity of people and electronic assets on the Internet. They allow for secure, encrypted online communication and are often used to protect online transactions.Digital certificates are issued by a trusted third party known as a certification authority (CA). The CA validates the identity of a certificate holder and “signs” the certificate to attest that it hasn’t been forged or altered in any way.New Uses For Digital CertificatesDigital certificates are now being used to provide security and validation for wireless connections, and hardware manufacturers are one of the latest groups to use them. Not long ago, Version Inc. announced its Cable Modem Authentication Services, which allow hardware manufacturers to embed digital certificates into cable modems to help prevent the pirating of broadband services through device cloning.Using Version software, hardware makers can generate cryptographic keys and corresponding digital certificates those manufacturers or cable service providers can use to automatically identify individual modems.This ‘ast-mile’authentication not only protects the value of existing content and services but also positions cable system operators to bring a broad new range of content, applications and value-added services to market.When a CA digitally signs a certificate, its owner can use it as an electronic passport to prove his identity. It can be presented to Web sites, networks or individuals that require secure access.Identifying information embedded in the certificate includes the holder’ s name and e-mail address, the name of the CA, a serial number and any activation or expiration data for the certificate. When the CA verifies a user’s identity, the certificate uses the holder’s public encryption key to protect this data.Certificates that a Web server uses to confirm the authenticity of a Web site for a user’s browser also employ public keys. When a user wants to send confidential information to a Web server, such as a credit-card number for an online transaction, the browser will access the public key in the server’s digital certificate to verify its identity.Role of Public-Key CryptographyThe public key is one half of a pair of keys used in public-key cryptography, which provides the foundation for digital certificates.Public-key cryptography uses matched public and private keys for encryption and decryption. These keys have a numerical value that’s used by an algorithm to scramble information and make it readable only to users with the corresponding decryption key.Others to encrypt information meant only for that person use a person’s public key. When he receives the information, he uses his corresponding private key, which is kept secret, to decrypt the data. A person's public key can be distributed without damaging the private key. A Web server using a digital certificate can use its private key to make sure that only it can decrypt confidential information sent to it over the Internet.The Web serve r’s certificate is validated by a self-signed CA certificate that identifies the issuing CA. CA certificates are preinstalled on most major Web browsers, including Microsoft Internet Explorer and Netscape Navigator.The CA certificate tells users whether they can trust the Web server certificate when it’s presented to the browser. If the validity of the Web server certificate is affirmed, the certificate’s public key is used to secure information for the server using Secure Sockets Layer (SSL) technology.Digital certificates are used by the SSL security protocol to create a secure “pipe” between two parties that seek confidential communication. SSL is used in most major Web browsers and commercial Web servers.3. Digital Wallets----A digital wallet is software that enables users to pay for goods on the Web ．It holds credit-card numbers and other personal information such as a shipping address ．Once entered，the data automatically populates order fields at merchant sites ．----When using a digital wallet，consumers don’t need to fill out order forms on each site when they purchase an item because the information has already been stored and is automatically updated and entered into the order fields across merchant sites ．Consumers also benefit when using digital wallets because their information is encrypted or protected by a private software code ．And merchants benefit by receiving protection against fraud ．----Digital wallets are available to consumers free of charge，and they’re fairly easy to obtain ．For example，when a consumer makes a purchase at a merchant site that’s set up to handle server-side digital wallets，he types his name and payment and shipping information into the merchant’s own form ．At the end of the purchase，one consumer is asked to sign up for a wallet of his choice by entering a user name and password for future purchases ．Users can also acquire wallets at a wallet vendor’s site ．----Although a wallet is free for consumers，vendors charge merchants for wallets ．----Digital wallets come in two main types: client-side and server- side ．Within those divisions are wallets that work only on specific merchant sites and those that are merchant agnostic ．----Client-based digital wallets，the older of the two types，are falling by the wayside，according to analysts，because they require users to download and install software ．A user downloads the wallet application and inputs payment and mailing information ．At that point，the information is secured and encrypted on the user’s hard drive ．The user retains control of his credit card and personal information locally ．----With a server-based wallet，a user fills out his personal information，and a cookie is automatically downloaded ．(A cookie is a text file that contains information about the user ．）In this scenario，the consumer information resides on the server of a financial institution or a digital wallet vendor rather than on the user’s PC ．----Server-side wallets provide assurance against merchant fraud because they use certificates to verify the identity of all parties ．When a party makes a transaction，it presents its certificate to the other parties involved ．A certificate is an attachment to an electronic message used to verify the identity of the party and to provide the receiver with the means to encode a reply ．----Furthermore，the cardholder’s sensitive data is typically housed at a financial institution，so there’s an extra sense of security because financial environments generally provide the highest degree of security ．----But even though wallets provide easy shopping online，adoption hasn’t been widespread ．----Standards are pivotal to the success of digital wallets ．----Last month，major vendors，including Microsoft Corp ．，Sun Microsystems Inc ．and America Online Inc ．announced their endorsement of a new standard called EMCL，or E-Commerce Modeling Language，to give Web merchants a standardized way to collect electronic data for shipping，billing and payment ．4. Grid StorageDefinition: Grid storage, analogous to grid computing, is a new model for deploying and managing storage distributed across multiple systems and networks, making efficient use of available storage capacity without requiring a large, centralized switching system.A grid is, in fact, a meshed network in which no single centralized switch or hub controls routing. Grids offer almost unlimited scalability in size and performance because they aren’t constrained by the need for ever-larger central switches. Grid networks thus reduce component costs and produce a reliable and resilient structure.Applying the grid concept to a computer network lets us harness available but unused resources by dynamically allocating and deal locating capacity, bandwidth and processing among numerous distributed computers. A computing grid can span locations, organizations, machine architectures and software boundaries, offering power, collaboration and information access to connected users. Universities and research facilities are using grids to build what amounts to supercomputer capability from PCs, Macintoshes and Linux boxes.After grid computing came into being, it was only a matter of time before a similar model would emerge for making use of distributed data storage. Most storage networks are built in star configurations, where all servers and storage devices are connected to a single central switch. In contrast, grid topology is built with a network of interconnected smaller switches that can scale as bandwidth increases and continue to deliver improved reliability and higher performance and connectivity.Based on current and proposed products, it appears that a grid storage system should include the following:Modular storage arrays: These systems are connected across a storage network using serial ATA disks. The systems can be block-oriented storage arrays or network-attached storage gateways and servers.Common virtualization layer: Storage must be organized as a single logical pool of resources available to users.Data redundancy and availability: Multiple copies of data should exist across nodes in the grid, creating redundant data access and availability in case of a component failure.Common management: A single level of management across all nodes should cover the areas of data security, mobility and migration, capacity on demand, and provisioning.Simplified platform/management architecture: Because common management is so important, the tasks involved in administration should be organized in modularfashion, allowing the auto discovery of new nodes in the grid and automating volume and file management.Three Basic BenefitsApplying grid topology to a storage network provides several benefits, including the following:Reliability. A well-designed grid network is extremely resilient. Rather than providing just two paths between any two nodes, the grid offers multiple paths between each storage node. This makes it easy to service and replace components in case of failure, with minimal impact on system availability or downtime.Performance. The same factors that lead to reliability also can improve performance. Not requiring a centralized switch with many ports eliminates a potential performance bottleneck, and applying load-balancing techniques to the multiple paths available offers consistent performance for the entire network.Scalability. It’s easy to expand a grid network using inexpensive switches with low port counts to accommodate additional servers for increased performance, bandwidth and capacity. In essence, grid storage is a way to scale out rather than up, using relatively inexpensive storage building blocks.四、译文新技术的计算机网络摘要：21世纪是信息经济的时代，作为这个时代的代表技术，计算机网络技术将在非常快的速度发展很快，不断创造性地将进入人们的工作，学习和生活中深。
计算机专业毕业论文参考文献(精选115个最新)
计算机专业是计算机硬件与软件相结合、面向系统、更偏向应用的宽口径专业。
通过基础教学与专业训练，培养基础知识扎实、知识面宽、工程实践能力强，具有开拓创新意识，在计算机科学与技术领域从事科学研究、教育、开发和应用的高级人才。
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计算机专业毕业论文参考文献一：[1]王琨. Linux操作系统下的网络多媒体技术应用[D].西安电子科技大学,2001.[2]陆海波. 智能型掌上电脑（PDA）的研究与开发[D].电子科技大学,2001.[3]高玉金. WINDOWS环境下并行容错局域网的研究及实现[D].燕山大学,2000.[4]陈军. 分布式存储环境下并行计算可扩展性的研究与应用[D].中国人民解放军国防科学技术大学,2000.[5]王霜. 瓦楞纸箱CAD系统开发[D].四川大学,2000.[6]王茂均. 织带机智能监测管理系统研究[D].大连理工大学,2000.[7]郭朝华. 多处理器并行的星上计算机系统设计[D].中国科学院上海冶金研究所,2000.[8]刘胜. 拖拉机作业机组仿真试验台自动变速控制系统的研究[D].中国农业大学,2000.[9]陈新昌. 冷藏、保温汽车静态降温调温性能测试系统的研究[D].河南农业大学,2000.[10]毛鹏军. 智能化温室环境参数微机监控系统的设计研究[D].河南农业大学,2000.[11]史志存. 电子鼻及其应用研究[D].中国科学院电子学研究所,2000.[12]孟笛. 复合材料加筋板壳结构稳定性设计的可视化研究和实现[D].大连理工大学,2000.[13]刘鹏民. 涡街电磁流量计机理的研究与开发[D].北京化工大学,2000.[14]付岩. 通用脚本语言GSCRIPT设计与应用的研究[D].中国科学院研究生院（计算技术研究所）,2000.[15]石争浩. 《计算机组成原理》CAI及其多媒体课件实现技术研究[D].西安理工大学,2000.[16]姚彤. 农机销售管理信息系统的设计与开发[D].东北农业大学,2000.[17]吕康娟. 基于地理信息系统(GIS)的小流域综合治理规划的研究[D].东北农业大学,2000.[18]邱建民. 北工大研究生教育管理信息系统[D].北京工业大学,2000.[19]刘春明. 变电站电压无功控制装置实用技术研究[D].华北电力大学,2000.[20]刘力力. 计算机系统性能评测与分析[D].中国科学院研究生院（计算技术研究所）,2000.[21]宋蓬勃. 基于校园网的高校研究生教务管理系统[D].山东师范大学,2000.[22]陈永华. 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计算机网络英文文献
电路交换网与vb调用数据库切换电路的连接设置的结果是保留了从发送端到接收端的包所通过的线路带宽。
其它的特性这一就是所有的包都沿同一个线路意味着如果包传输超过了时序那它将不能到达接收端.由于没有路径用来进行包交换，所以要想不同的包沿不同的本文源自六维论文网路径传送就是能依靠网络的条件了。
这样包即便是超过了时序它们也有可能到达的。
包交换技术比线路交换技术更能容错。
事实上，这也是它被发明的理由！当一个交换开头被拉下，则所有使用它的线路将被切断并且其余的包将不能再被传送。
此时如果在进行包交换，包将在已选择的路径上停止交换。
预先建立一条路径也开创预先保留带宽的可能性。
如果带宽被保留，那么当一个包到达时，通过保留的带宽它可以被立即发送出去。
假如没有带宽被保留用于包交换，那么所有的包将不得不等待着被转发。
预先保留带宽意味败。
因此，在线路交换(在设置时)和包交换(在包发送时)的不同时间拥塞都可能发生。
如果为特定的用户建立一条线路那么当这个用户没有数据传送时，则这些保留下来的带宽将被浪费而不能用于其它用户的传输。
而包交换则不会浪费带宽，因此它在系统宽带方面的应用更有前景。
理解电路交换和包交换的这种商业差别是极其重要的。
这种商业差别是在质保服务和浪费资源相对不质保服务和不浪费资源的。
包交换是利用存储器并向前发送的。
包是先存储在路由器的内存里然后再发送到下一个路由器的。
和电路交换一样信息位也是连续不断地通过导线传输的。
存储转发技术增加了延迟时间。
另一个不同是电路交换是完全透明的。
发送者和接收者可以使用他们想要的任一比特速率，格式和帧同步.这通信公司不知道也不关心这的。
而在包交换中载体决定了基本的参数的。
用一个简单比喻它们就像一个是公路一个是铁路。
在以前，用户决定介质的大小，速度和特性。
而后来这些都由通信公司做了的。
这些都是透明的它允许声音，数据和传真共同存在于电话系统里。
电路交换和包交换的最后一个不同点是计费方式。
电路交换的计费是按照传统的距离和时间的。
比如移动电话除打国际电话外距离是不列入计算的，而时间也只是列入一个简单的计算(例:拔打2000分钟电话比1000分钟电话花费的多并且晚上或周末也比平时来得便宜)。
时间对于包交换来说是没有问题的，但是传输流量却是个问题。
ISPs为家庭用户的计费方式基于按一个月的流量的一半的，这是因为它们用得相对较少并且他们的顾客也很好理解这种计费方式。
但是主干网络中心的收费是基于它们的流量的。
这些不同列在图2-40里。
项目电路交换包交换
呼叫设置需要不需要
专用物理线路是否
每个包沿相同路径是否
包的到达中有规则的是否
是否会致命的崩溃是否
带宽利用固定动态分配
可能的时间堵塞在设置时在每个包时
可能浪费带宽是否
以存储转发进行发送否是
透明性是否
收费按分钟按包
图2－40：比较电路交换网络和包交换网络的不同
电路交换和包交换是两者都是非常重要的，我们将立即在详细的资料里提及并描述它们之间各种不同的技术。
2.6 移动电话系统
传统的电话的系统将不能满足用户的大量增长（即有一天实现了终端到终端的光纤连接）。
人类在进步。
因此有很多的人关心无线电话技术。
在下面的章节我们将用详细的资料来学习这些主题。
无线电话可以分为基本的两种：无绳电话和移动电话（有时也叫蜂窝电话）。
无绳电话设备是由痤机和听筒组成它们被安装在用户的家里。
它们从不被应用于网络，所以我们没有办法做进一步的检测。
取而代之，我们将把焦点放在在声音和数据通信上有广泛应用的移动系统上。
移动电话经历了三个不同的发展阶段，每个阶段都有不同的技术：
1．模拟声音
2．数字声音
3．数字声音和数据（互联网，电子邮件，etc.）
虽然我们主要讨论这系统技术，但是我们也有必要注意政府和市场对它的巨大影响。
第一个移动电话系统是在美国由受美国国家联邦通讯委员会(FCC)委托的美国电话电报公司(AT&T)设计的。
结果在整个美国就有了一个简单的(模拟)系统并且移动电话开始在加利福尼亚上市同时也在纽约得到应用。
相反的，当移动电话来到欧洲时，由于每个国家都设计了自己的系统，所以结局很惨败。
当数字技术到来时，欧洲从前面的失败中吸收教训，政府和邮政制定了简单系统(GSM)的统一标准，因此移动电话在欧洲的任何一个地方都是通用的。
此时，美国政府决定不把标准商业化因而它失去了数字市场。
这个决定导致不同的设备生产商生产出不同的移动电话。
结果现在美国有两不可兼容的数字移动电话在使用(加强了一家就会削弱另一家)。
即使美国拥有移动电话的所有权，但是在应用上欧洲要远远超过美国的。
原因之一就是整个欧洲拥有相同的简单系统。
然而更多的是由于美国和欧洲的基本电话数量不同。
在美国移动电话和固定电话是共用的，因此对于用户没有办法区分(212)234-5678到底是固定电话(拨打是便宜的或者是免费的)还是移动电话(拨打是昂贵的)。
为了使人们从使用电话中获益，电话公司决定为引入呼叫而花自己的钱制造移动电话。
结果导致，很多人怕由于呼叫而收到一大笔帐单而不愿意买移动电话。
在欧洲移动电话有特殊的区号(如800,900之类的数字)，所以它很快就得到了认可。
因而在一般的“叫方付费”的原则在欧洲也被应用于移动电话了(除国际电话分开收费外)。
在欧洲采用颁布广泛的已经付费的移动电话的影响巨大(超过同地区的75%)。
移动电话可以在很多的商店里购买而不像购买收音机那样需要很多手续。
谁付费谁使用，他们预先存入，比如20或50 euro并且在快用完的时候可以用PIN码进1355。