Discussion on HDLC Frame Format of HDLC & Transfer Mode
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Discussion on HDLC: Frame Format of HDLC & Transfer Mode (Computer Science)
Topics
- Introduction on HDLC
- Primary and Secondary Stations
- HDLC Frame Format
- Transfer Modes:
- Asynchronous Response Mode (ARM) : Normal Response Mode (NRM)
- Asynchronous Balanced Mode (ABM)
HDLC
- HDLC stands for High Level Data Link Control
- It is a bit oriented transmission protocol
- It works at a data link layer which is second layer (layer 2) of OSI seven layered architecture model for data communication
- It embeds information in a data frame that allows devices to control data flow and correct errors
- HDLC is proposed by IBM in 1970s from SDLC i.e.. Synchronous Data Link Control Standard
- Sessions are created for communication purpose in it.
Primary & Secondary Stations
- Primary Station: The one who sends commands. Data Link Management and Connection⟋Disconnection are the basic responsibilities of primary station. Frames issued by primary station are called as commands.
- Secondary Station: These are the stations which responses and frames issued by secondary stations are called as responses.
- Combined Station: It acts both like primary and secondary stations. They have both commands and responses.
Frame Format of HDLC
- I-Frame: Information Frame-0 bit in control field
- S-Frame: Supervisory Frame-10 bit in control field
- U-Frame: Un-numbered Frame-11 bit in control field
Transfer Mode
Transfer Modes:
- Normal Response Mode (NRM) : Point to Point and Point to Multipoint
- Asynchronous Balanced Mode (ABM) : Point to Point
Normal Response Mode (NRM)
Asynchronous Balanced Mode (ABM)
- Point to Point:
- Workstation acts as both primary and secondary stations depending upon the requirement.
MCQ
Q1. HDLC stands for:
- High Data Logical Control
- High Level Data Link Control
- High Destination Logical Control
- High Definition Logical Control
Answer: B
Q2. HDLC is:
- Bit oriented
- Code transparent
- Both (a) and (b)
- None of these
Answer: C
#Introduction on HDLC
#Primary and Secondary Stations
#HDLC Frame Format
#Transfer Modes:
#Asynchronous Response Mode (ARM)
#Normal Response Mode (NRM)
#Asynchronous Balanced Mode (ABM)
✍ Mayank