L12 - High level data link control(HDLC Important link...

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High level data link control (HDLC) Important link error control standard. Uses the 01111110 start and end flag with data field bit stuffing. Frame format: Address field - mainly needed when a line is connected to multiple terminals: It isn’t needed for point-to-point communication, but is available for other purposes.
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Control field contains sequence numbers, acknowledgments, and frame type identification. Data field is variable, of arbitrary length. With the 16 bit FCS it is usually is limited to < 65,536 bits, else some double errors might go undetected. The FCS is computed by a CRC polynomial of 16 or 32 bits.
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There are 3 types of frames. N(S) = Send sequence number N(R) = Receive sequence number S = Supervisory (acknowledgment control) bits M = Unnumbered function bits P/F = Poll/Final bit.
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An information frame has a place for a piggybacked acknowledgment. A supervisory frame carries an acknowledgment when there is no information frame to send. The Poll/Final bit was used to poll in the
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This note was uploaded on 07/16/2011 for the course EE 362 taught by Professor Unknow during the Spring '11 term at Penn College.

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L12 - High level data link control(HDLC Important link...

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