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This Concept Map, created with IHMC CmapTools, has information related to: chp7, Packets,Frames,and Error Detection Error Detection Transmission Errors, the problems of lost,changed, or spuriously appearing bits account for much of the complexity needed in computer networks. caused by lightning, power surges, and other electro-magnetic interference can introduce unwanted electrical currents in the electronic components or wires used for communication., Packets:data that network systems divide into small blocks. Two facts motivate the use of packets Second:because communication circuits and the associated modem hardware are expensive,multiple computers often share underlying and hardware., Transmission Errors ways to detect errors Parity bits and Parity Checking, Transmission Errors are the problems of lost,changed, or spuriously appearing bits account for much of the complexity needed in computer networks., Packets:data that network systems divide into small blocks. Two facts motivate the use of packets First:a sender and receiver need to coordinate transmission to ensure that data arrives correctly., Transmission Errors ways to detect errors Cyclic Redundancy Checks, Packets:data that network systems divide into small blocks. sometimes Computer Networks are often called packet networks or packet switching networks because they use packet technology., Parity bits and Parity Checking purpose is designed to help detect transmission errors, sends one extra bit of information with each character. Although it allows a reciever to determine if a single bit has been changed, parity cannot detect transmission errors that change an even number of bits., Packets:data that network systems divide into small blocks. why?? Dividing data into small packets ensures that all sources receive prompt service because it prohibits one source from gaining exclusive access for an arbitrarily long time., Packets,Frames,and Error Detection The concepts of packets Packets:data that network systems divide into small blocks., Packets,Frames,and Error Detection Frames the term frame is used to denote the definition of packet used with a specific type of network., Transmission Errors ways to detect errors Detecting Errors with Checksums, Parity bits and Parity Checking the idea is network systems usually send a small amount of additional information with the data. A sender computes the value of the additional information from the data, and a receiver performs the same computation to verify that the packet was transmitted without error., Cyclic Redundancy Checks which uses two simple components: a shift register and an exclusive or (xor) unit., Detecting Errors with Checksums how?? to compute a checksum, the sender treats the data as a sequence of binary integers and computes their sum.