HDLC

Question 1

What is High-level Data Link Control (HDLC)?

Answer 1

It is a group of communication protocols of the data link layer for transmitting data between network points or nodes. Data is organized into frames because it is a data link protocol. A frame is transmitted via the network to the destination, that then verifies its successful arrival. HDLC ensures the error-free transmission of data to the proper destinations and controls the data transmission speed.

Question 2

What are the HDLC frame types?

Answer 2

1. Information frames (I-frame): can transfer the user data and control the data associated with the user data.
2. Supervisory frame (S-frame): can transfer control data. Generally, it includes the data link layer structure and the error controls.
3. Unnumbered frame (U-frame): U-frames are constrained for framework administration.

Question 3

What is the payload in a HDLC frame?

Answer 3

Payload is meant to describe all of the data that the frame is holding, this includes the flags.

Question 4

What is a flag in HDLC?

Answer 4

Frame indicate and represent an entity of data or a protocol of data unit often transmitted or transferred from one station to another station. Each and every frame on link should begin and end with Flag Sequence Field.

Question 5

What is a frame in HDLC?

Answer 5

High-Level Data Link Control (HDLC) generally uses term “frame” to indicate and represent an entity of data or a protocol of data unit often transmitted or transferred from a place to another place.

Question 6

What are the parts of a frame in HDLC?

Answer 6

The flag field, the address field, the control field, the Information field, the Frame Check Sequence.

Question 7

What is the flag field in HDLC?

Answer 7

The flag field tells the beginning and end of a frame

Question 8

What is the address field in HDLC?

Answer 8

The address field tells the frame where to go.

Question 9

What is the control field in HDLC?

Answer 9

This tells the frame how to communicate.

Question 10

What is the information field in HDLC?

Answer 10

This contains the data that the user is trying to send or receive, differs from frame type to frame type.

Question 11

What is the frame check sequence in HDLC?

Answer 11

This in short is HDLC error correction.

Question 12

Where are semiconductors used?

Answer 12

In any electronic device.

Question 13

What are semiconductors?

Answer 13

They are like the name suggests, they have a conductivity between conductors and insulators. This means they can also change their conductivity.

Question 14

What are diodes?

Answer 14

Diodes are semiconductors that allow flow of voltage in only one direction. This can convert ac to dc as well.

Question 15

What is zener voltage?

Answer 15

It describes a threshold in the Zener diode. This is a diode where the flow is in one direction, then when the voltage hits a certain amount, the direction changes.

Question 16

What is a bridge rectifier?

Answer 16

This turns ac into dc

Question 17

What are the HDLC modes?

Answer 17

NRM, ARM, ABM.

Question 18

What is NRM?

Answer 18

In simple words, a secondary station that is running in an unbalanced communications or configuration environment may only communicate when being commanded or signaled to do so by the primary station. In other words, a secondary station must receive command or permission from the primary station to transfer or transmit response.

Question 19

What is ARM?

Answer 19

Unbalanced Configuration in which the primary station may initiate or start a data transfer as well as the secondary station can also start or initiate data transfer without any explicit permission or command from the primary station to transfer data. We usually have only one primary station and multiple secondary stations.

Question 20

What is ABM?

Answer 20

ABM is a type of Balanced configuration in which a secondary station can initiate data transfer without any explicit permission or command from the primary station. ABM also provides a reliable point-to-point link service. It is also used to provide a service that supports either a datagram or reliable network protocol that can act as both a primary and a secondary.

Question 21

What is current density?

Answer 21

The quantity of electric current flowing through a unit cross-sectional area is characterized as current density.

Question 22

What is resistance?

Answer 22

In an electrical circuit, resistance is a measure of the resistance to current flow. The unit of resistance is ohms. Ohm formula=
V = IR, I = V/R, and R= V/I.