Information transfer format (I-Frame) – It transports the numbered frames in a sequential manner, which contain the information field.There are three types of frames information, supervisory and unnumbered. The HDLC uses a group of commands and responses for its working. Checksum field -In this field, the bits are reserved for the performing the cyclic redundancy code.Data field – This field is used to hold the information.Control field – The bits in the control field is intended for the sequence number and acknowledgements.Address field – It is used to describe the terminal.Frame format for the bit-oriented protocols Standard HDLC can have different devices in the ends.
The Cisco proprietary HDLC only works when the devices in both of the ends of the link are of cisco.
The default encapsulation protocol in the Cisco devices is the HDLC. The frame structure of HDLC contains the address, control, data, checksum and flag fields. Here bit oriented approach signifies that the single bit is used to present the control information. The HDLC protocol follows the bit-oriented concept and uses bit stuffing for achieving data transparency.
#SKETCHING A PPP FRAME ISO#
Both SDLC and HDLC protocol are developed by IBM and submitted to the ANSI and ISO for the acceptance as the international standards. SDLC is the predecessor of the HDLC which stands for the Synchronous Data Link Control protocol. The encapsulation of the data means to change the format of the of the data. HDLC (High-level Data Link Control) is a WAN protocol intended to perform the encapsulation of the data in the data link layer.
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