Data Link Protocols Asynchronous Protocols XMODEM frame ...

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Bit-oriented protocol• Represent more information into shorterframe• Avoid the transparency problemsBit-orientedProtocolsSDLC HDLC LAPs LANsSDLC: Synchronous data link control – IBMHDLC: High-level data link control – ISOLAPs : Link access procedure19 of 53HDLC• Support half/full – duplex over point-topointand multipoint links• HDLC system characterization• Station types• Configurations• Communication modes• FramesHDLC station types• Primary station• The station that controls the medium by sending“command”• Secondary station• The station that “response” to the primary station• Combined station• The station that can both command and response21 of 5322 of 53HDLC configurationsHDLC Configurations:Unbalanced (master/slave)• The relationship of hardware devices ona link• 3 configurations of all stations(primary/secondary/combined)• Unbalanced• Symmetrical• Balanced23 of 5324 of 534
HDLC Configurations:SymmetricalHDLC Configurations:Balanced25 of 5326 of 53HDLC communication modesMode : describe “Who controls the link”NRM: Normal response mode (master/slave)ARM: Asynchronous response mode(secondary can initiate if idle, all transmissions are made to primary station)ABM: Asynchronous balanced mode (point-to-point equal)27 of 53HDLC frame• 3 frame types• Information frame (I-frame)• Supervisory frame (S-frame)For ACK, Flow/Error controls• Unnumbered frame (U-frame)For Mode setting, Initialize, Disconnect28 of 53HDLC FrameHDLC Frame29 of 5330 of 535
Page 1 and 2: Data Link ProtocolsData Link Protoc
Page 3: Control framesControl frames13 of 5
Page 7 and 8: HDLC frame: Poll / FinalHDLC Frame:
Page 9: HDLC: U-Frame control fieldHDLC: Po

Data Link Protocols Asynchronous Protocols XMODEM frame ...

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