Data Link Protocols Asynchronous Protocols XMODEM frame ...

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