Types And Characteristics Of WANs Information Technology Essay

Types And Characteristics Of WANs Information Technology Essay A Wan is a large area network that expands in a geographical area, such as a country or a continent. It is known also as a communication system that connects computer networks such as LANs (local area network) and MANs (metro area network). The connections go through local, national or international areas public or privately, using generally phones lines, referred to as POST, or employing PSTN (public switched telephone network) or fibre optics, creating the link between networks located in different facilities. A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any one organization but rather exist under collective or distributed ownership and management. WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the longer distances. These networks contain a collection of machines to execute some programs which are called hosts. These are connected to networks that have communication through routers with each LAN and a WAN interface. Remote access is something vital for the companies and users because it allows you to have mobility and work through different areas. Also it gives the benefit to get better business out of your area. Basically a WAN generates new applications viable, and some of them can cause important effects in whole society. In order to give some idea of important uses, some of them they are already commented before, we can see emphasize: The access to remote programs. The access to remote data bases. Facilities of added value communication. The principal components are routers, switches and modems. Devices on the subscriber premises are called customer premises equipment (CPE). The subscriber owns the CPE or leases the CPE from the service provider. A copper or fibre cable connects the CPE to the service providers nearest exchange or central office. This cabling is often called the local loop, or last-mile. Then Devices that put data on the local loop are called data circuit-terminating equipment, or data communications equipment (DCE). The customer devices that pass the data to the DCE are called data terminal equipment (DTE). The DCE primarily provides an interface for the DTE into the communication link on the WAN cloud. Types and characteristics of WANs: The local area networks (LAN) are significantly different from the wide area network (WAN). The LANà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ãƒ ¢Ã¢â‚¬Å¾Ã‚ ¢ sector is one of the fastest growths in the industry of the communications. The local area networks own the following characteristics. Generally, the channels are property of the user or company. The connections are lines (from 1 Mbps to 200 Mbps). The DTEs is connected to the network via channels of low speed (from 600 bits to 56 Kbits). The DTEs are near to each other, generally in a same building. A DCE can be used to exchange between different configurations, but they are not as frequently as in the WAN. The lines in LANs are better quality than the channels in the WAN, because to the differences between the local area networks and the wide network area, their topologies can take very different forms. The structure of the WAN tends to be more irregular, due to the necessity to connect many terminals, computers and switching centres. Circuit Switching: The circuit switching is a WAN switching method which establishes, maintains and ends dedicated physical circuit through a carrying network for each session of communication. The switching circuit, which is used widely in the networks of the telephone companies, operates of form similar to one circuit, which is widely used in telephone company networks, operates similar to a normal telephone call. ISDN is an example of a circuit-switched WAN technology. Connections circuit switched one site to another are triggered when necessary and generally require low bandwidth band. The circuit switched connections are used primarily to connect remote users and mobile users to the corporate LAN. Also it is used as backup lines to circuit higher speeds, such as Frame Relay and other dedicated lines. One advantage is it is highly reliable for its function. A disadvantage is all the time spends to set up the channel and also there is the single point failure which can cause a dis ruption in communications. Message Switching: a computer is in charge to accept connected traffic of networks to him. The computer examines the direction that appears in the head of the message towards the DTE that must receive it. This technology allows recording the information to take care of it later. The user can erase, store, route or answer the message of automatic form. Picture taken from technet.microsoft.com Packet Switching: In this type of network the data of the users are disturbed in smaller pieces. These fragments or packages, you are inserted within information of the protocol and cross the network like independent organizations. Connectionless and Connection-Oriented Services: they happen directly of the free situation to the way to transfer data. These networks do not offer confirmations, flow control and neither recovery of errors applicable to the entire network, although these functions if they exist for each particular connection. An example of this type of network is Internet. In connection-Oriented packets switched, the multiplexing concept exists in channels and ports are known as virtual circuit or channel. The user pretends to have a dedicated resource, when he shares with another one then what it happens is that they take care of bursts of traffic of different users. General routing issues Congestion is about too much presence of packages in a part of one subnet. In cases of extreme congestion, routers start to reject packages, decreasing the system performance. The reasons of congestion are many, some of them are: If in 4 lines, the information arrives to him at router and all needs the same line of exit, it exists competition. Insufficient amount of memory in routers. But if you add more memory, this just helps until certain point because the time to arrive at first from the queue can be so long. Slow processors in routers. The analyse process of the packages are expensive, so slow processors can cause congestion. In that way the congestion propagates to the others routersà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ã‚ ¦ The flow control and the control of congestion are not the same: Flow control: is in charge of a fast emitter does not saturate to a slow receiver. Control of Congestion: its function is to try to avoid that the network is overloaded. The solutions for the problem of congestion can be divided in two classes: Open Loop: They try to solve the problem with a good design. They use algorithms to decide when to accept more packages, when to discard them, etc. But they do not use the actual situation of the network. Closed Loop: The solution in this case is based on the feedback of the line. Generally they have three parts: 1. The system is monitored to detect when and where it happens the congestion. 2. This information goes towards where actions can be taken. 3. The operation parameters of the system adjust to correct the problems. Several measures of the performance can be used to measure the congestion. The main measures used are: % of discarded packages, Queue length, Number of packages that makes timed out and/or relayed, the average delay of the packages. 3. Addressing and routing It is necessary that any machine or host have one address, in order to get the information to the network. In the case of Internet, this are called IP address, and to each machine of the Network is assigned one. An IP address is a 32 bit number represented as four octets. Each of these four octets is in the range between 0 to 255. Class A: 10.0.0.0 a 10.255.255.255 (8 bits red, 24 bits hosts) Class B: 172.16.0.0 a 172.31.255.255 (16 bits red, 16 bits hosts) Class C: 192.168.0.0 a 192.168.255.255 (24 bits red, 8 bits hosts) Class D addresses are used for multicasting Class E is for experimental purposes. PTO Switched Services

Struggle between Romantic and Enlightened Thought Essay -- Enlightened

We are often presented with potential explanations or answers to current philosophical dilemmas through temporally relevant works of literature. The late eighteenth and early nineteenth century, or the Romantic Era, is characterized as a time in history in which aristocratic social and political norms of the Enlightened Era were radically questioned and investigated. For Enlightened thinkers, the idea of â€Å"being† was composed of three essential parts, the true, the beautiful, and the good. Isaac Newton’s contributions to scientific method were fascinating in the respect that they seemed to provide truths regarding quantitative matter. Yet his science failed to provide us with knowledge of all qualitative matters, such as morals and aesthetics. With Newton’s laws held in such high regard, the model of being was decomposed to simply the â€Å"true,† or scientific knowledge which is recognized and confirmed through his laws of motion, proceeding to exclud e all matters which Newton’s lens could not be pointed. It is apparent that problems would arise as a result. Qualitative matters could not be explained through Newton’s science, which created a sense of bewilderment. People began to question whether certain quantitative matters actually pertained to all aspects of life. Rousseau, whose writings contributed immensely to Romanticism, proposes a new model of â€Å"being,† which is later confirmed by Kant and Schiller. His new model strengthens the enlightened ideas of being, and allows for the application of â€Å"being† to both the quantitative and qualitative. Mary Shelley’s â€Å"Frankenstein† provides an explanation to the struggle dealing with â€Å"true being† between Enlightened and Romantic thinkers while exemplifying Romantic thought on happiness. ... ...nize the monster as more then a hideous being. Instead Walton understands the morals and ethics that lie beneath the monsters flesh, eventually appreciating his true goodness, in a similar fashion that Schiller and Kant propose. The significance of the philosophical dilemma between Enlightened and Romantic thinkers is exemplified through Mary Shelley’s Frankenstein. This symbolic literary work provides readers with insight to the problem philosophers of the time faced when dealing with the idea of true being. Through the monster, the townspeople and Walton, we are able to gain a complete understanding of the situation Rousseau, Kant, and Schiller dealt with. In the end, it is clear that in order to experience true being and beauty one must not rely solely on Newton’s scientific lens, but must also understand the quantitative matters such as morals and ethics.

During protestant reformation

Henry Vic's people became angry with the church, and German monk Martin Luther spoke out (95 theses). B. The Elizabethan Era (p. 288) Elizabeth l, prove to be great ruler. Sent Sir Francis Drake across globe, and Sir Walter Raleigh tried to put colony in Virginia. Greatest feat is defeating the Spanish Armada. C. The Rise of the Stuart and The Defeat of the Monarchy (p. 289) After death of Elizabeth, James I took throne (Scotland). This angered Catholics after his support of Church of England. Charles I took over in 1625 and relations withPuritans worsened, also after he dismissed Parliament. This put England into civil war. Oliver Cromwell and puritans defeated Royalists. Puritans made a commonwealth. Big set back. Once Charles II came back from exile to assume the throne restoration began. D. The Renaissance (p. 290) Art, poetry, music, theatre, all thriving during this time period. Started in Italy and spread throughout Europe. Life on Earth began to hold more energy and interest than thoughts of afterlife and religion. A renaissance man was a well rounded man who did the best he could with his or her talents. This was the time of Shakespeare,Galileo, and other creative people who invented and developed things to cultivate time period. Such as compass, printing press, and things like that. People began to explore life on earth and began to question many important things. Theatre was huge during this time, and King James Bible was made. The time period concluded in 1660 II. Renaissance Literature A. Pastoral Poems and Sonnets (p. 291) Energy became vibrant in literature. Sir Phillip Sidney, Sir Walter Raleigh and Edmond Spencer all put forth great literature. A pastoral poem is one that represents an idealized manner of shepherd life. Literature of Nature also emerged evilly.B. Shakespearean Drama (up. 292-93) Shakespeare contributed so much to drama and literature during time period. Mystery, mystical and morality plays developed greatly. Interludes and Lati n and Greek dramas. He contributed tragedy and Comedies that to this day are famous. Also satires. His plays displayed many events and stories throughout history C. The Rise of Humanism (up. 294-95) Art, History, Philosophy and literature is what Humanists studied. English humanists were Erasmus, Sir Thomas More. Utopia was famous work of literature. Many translations also appeared. D. Spiritual and Devotional Writings (up. 295-96)King James Bible did more to mold English writing than anything. Scholar John Wickedly was scrutinized for his translation of spiritual scripture. King James Bible influenced John Million's â€Å"Paradise Lost†. Also puritan writer John Bunyan who was famous for his allegory arose during this time. E. The Metaphysical and Cavalier Poets (up. 296-97) Ben Johnson was an accomplished poet related to Shakespeare because of that manner or writing. Ben Johnson had a group of men who followed him called â€Å"Sons of Ben†, this included Robert Heroi c, Richard Lovelace, and Sir John Suckling. John Done represents the Metaphysical poets.

The European Tradition Of Education - 852 Words

Horace Mann, is often referred to the Father of the Common School, he began his career as a lawyer and legislator. He was elected as Secretary of a new Massachusetts Board of Education in 1837. He used his power to create an educational reform. He believed that every child could receive a basic education funded by local taxes. Soon his influence spread beyond Massachusetts, more and more states began to take up the idea of universal schooling. Mann was influential in the development of teacher training schools and the earliest attempts to professionalize teaching. Mann didn’t not believe in the European theory where men are divided into classes some left to toil and earn, and others to seize and enjoy. He wanted equal education for everyone not based on citizen’s social rank. The European tradition of education was centered in the family rather than in schools did not take root in the United States, because the pattern of the extended family meaning several generations living under one roof disappeared. As families moved to take advantage of free land, the old educational patterns broke down, and new forms were created As a result, Americans began to give more and more educational responsibility to the schools. The basic skills of reading, writing and arithmetic were just the start; over the decades society has assigned many other skills previously learned in the homes to be taught in schools. He wanted education to be universal, not just for the rich but for everyoneShow MoreRelatedThe Impact Of Modern Public Sphere On The Middl e East1322 Words   |  6 Pagesapproach backfired and the Middle East found themselves struggling to establish their own modern identity and falling victim to becoming more like the Europeans. 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