4 flow control a communication protocol also prevents

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Unformatted text preview: ment Corporation), Intel, and Xerox in 1980, and subsequently, a slightly modified version of it was adopted by the IEEE as a standard LAN technology. The network topology used for Ethernet is multi-access bus topology. The communication medium used is low-loss coaxial cable having a data transfer rate of 10 Mbps. A message is transmitted from one node to another by breaking it up into packets (called frames in Ethernet) and then by broadcasting the packets to the bus. An address designator is associated with each packet. As a packet travels on the bus, each node checks whether the packet is addressed to it and the addressee node picks up the message. The ARPANET of the Advanced Research Projects Agency of the U.S. Department of Defense was the first WAN. It connected about 40 universities and research institutions throughout the United States and Europe with about 50 computers ranging in size from mini-computers to supercomputers. ERNET (Education and Research NETwork) is a WAN, which links several education and research institutions in India. NICNET (National Informatics Centre's NETwork) is a WAN, which links several offices of NIC (National Informatics Centre) of India up to district headquarters. Indian Railways also has its own WAN which links its booking offices across the nation facilitating the passengers to book tickets on most major trains from anywhere in India. Similarly, international airlines worldwide also link their computers to form a WAN that facilitates booking of flight tickets on international flights. SWIFT is a WAN that interconnects the computers of International banks to reconcile their accounts and for electronic funds transfer. The Internet (described in the next chapter) is a WAN that encompasses many LANs and computers across the world. COMMUNICATION PROTOCOLS A protocol is a set of formal operating rules, procedures, or conventions that govern a given process. A communication or network protocol, therefore, describes the rules that govern the transmission of data ov...
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This document was uploaded on 04/07/2014.

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