High-level Data Link Control (HDLC)

High-level Data Link Control (HDLC) is an enhanced derivative of SDLC from IBM. HDLC is the default serial link protocol for Cisco routers. Nearly all other routers on the market use PPP for link control. HDLC is a Data Link layer protocol. These protocols allow computers on either end of a physical connection (end stations) to communicate.

• STATION TYPES
• COMMUNICATIONS MODES
• DATA TRANSFER MODES
• FRAME STRUCTURE