SDLC (Synchronous Data Link Control) was invented by IBM way, way back when. It is a full-duplex, synchronous, point-to-point protocol. It is the lowest layer in the SNA protocol suite.Can any give me or point me to a short and simple explanation of what HDLC is? _______________________________________________ Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
A packet in SDLC begins with a flag (01111110), data bytes, a CRC byte, and a closing flag byte. Between frames you'll see all marking bits. Back in the 70s one could purchase a USART (Universal Synchronous Receiver Transmitter) in a 40 pin package. Don't know about today.
I don't want to start a flame war with the Europeans, but I recall that a European standards committee (CCITT? ISO?) decided that SDLC was pretty cool, so they changed one bit, changed the name to HDLC (High-level Data Link Control), and called it their own.
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