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Unformatted text preview: -61-AANSWERS TO NSWERS TO QQUESTIONSUESTIONS14.1 Logical link control (LLC): provides an interface to higher layers and performflow and error control; medium access control (MAC): provides addressing forphysical attachment points to the LAN and provides medium access; physical:defines the topology, transmission medium, and signaling.14.2A MAC addressdefines a physical point of attachment to the LAN. An LLCaddressidentifies a particular LLC user (next higher layer above LLC).14.3 Unacknowledged connectionless service:This service is a datagram-style service.It is a very simple service that does not involve any of the flow- and error-controlmechanisms. Thus, the delivery of data is not guaranteed. Connection-modeservice:This service is similar to that offered by HDLC. A logical connection is setup between two users exchanging data, and flow control and error control areprovided. Acknowledged connectionless service:This is a cross between theprevious two services. It provides that datagrams are to be acknowledged, but noprevious two services....
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- Fall '11