CBSE Class XIIth Computer Science Evolution of Networking -Shruti Mehra
Introduction Exchange of information through the use of speech, signs or symbols is called communication Communicating with people over a distance is known as telecommunication.
ARPANET * ARPANET- Advanced Research Projects Agency Network the granddad of Internet was a network established by the US Department of Defense (DOD). The work for establishing the network started in the early 1960s and DOD sponsored major research work, which resulted in development on initial protocols, languages and frameworks for network communication. It had four nodes at University of California at Los Angeles (UCLA), Stanford Research Institute (SRI), University of California at Santa Barbara (UCSB) and University of Utah. On October 29, 1969, the first message was exchanged between UCLA and SRI *
INTERNET ARPANET expanded to connect DOD with those universities of the US that were carrving out defense-related research. It covered most of the major universities across the country. The concept of networking got a boost when University College of London (UK) and Royal Radar Network (Norway) connected to the ARPANET and a network of networks was formed. * The term Internet was coined by Vinton Cerf, Yogen Dalal and Carl Sunshine of Stanford University to describe this network of networks. Together they also developed protocols to facilitate information exchange over the * t. Transmission Control Protocol (TCP) still forms the backbone of networking.
TELENET Telenet was the first commercial adaptation of ARPANET introduced in 1974. With this the concept of Internet Service Provider (ISP) was also introduced. The main function of an ISP is to provide uninterrupted Internet connection to its customers at affordable rates. *
World Wide Web x With commercialization of internet, more and more networks were developed in different Each network used different protocols for communicating over the network. This prevented different networks from connecting together seamlessly. In the 1980s, Tim Berners- Lee led a group of Computer scientists at CERN, Switzerland, to create a seamless network of varied networks, called the World Wide Web (www) part of the world World Wide Web is a complex web of websites and web pages connected together through hypertexts. Hypertext is a word or group of words linking to another web page of the same or different website. When the hypertext is clicked, another web page opens. *
Switching Techniques In large networks, there may be more than one paths for transmitting data from sender to receiver. Selecting a path that data must take out of the available options is called switching. There are two popular switching techniques circuit switching and packet switching *
Circuit Switching When a dedicated path is established for data transmission between sender and receiver, it is called circuit switching. When any network node wants to send data, be it audio, video, text or any other type of information, a call request signal is sent to the receiver and acknowledged back to ensure availability of dedicated path. This dedicated path is then used to send data. ARPANET used circuit switching for communication over the network. *
Advantages of Circuit Switching * Once path is set up, the only delay is in data transmission speed * No problem of congestion or garbled message Disadvantages of Circuit Switching * Long set up time is required * A request token must travel to the receiver and then acknowledged before any transmission can happen * Line may be held up for a long time
Packet Switching As we discussed, the major problem with circuit switching is that it needs a dedicated line for transmission. In packet switching, data is broken down into small packets with each packet having source and destination addresses, travelling from one router to the next router *
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