Deck 7: Data Link Control Protocols

Question 1

________ enables a receiver to regulate the flow of data from a sender so that the receiver's buffers do not overflow.

A)Flow control
B)Link control
C)Data control
D)Error control

Answer 1

A

Question 2

In a data link control protocol,________ control is achieved by retransmission of damaged frames.

A)DLHC
B)data
C)error
D)flow

Answer 2

C

Question 3

HDLC uses asynchronous transmission.

Answer 3

False

Question 4

In situations where the bit length of the link is greater than the frame length,serious inefficiencies result.

Question 5

Error control enables a receiver to regulate the flow of data so that the receiver's buffers do not overflow.

Question 6

Transmission time is not proportional to the length of the frame.

Question 7

Data are sent in blocks called ________.

A)links
B)units
C)entities
D)frames

Question 8

The ________ time is the time it takes for a bit to traverse the link between source and destination.

A)relay
B)flow
C)transmission
D)propagation

Question 9

The sending station must not send frames at a rate faster than the receiving stations can absorb them.

Question 10

Selective reject is a useful choice for a satellite link because of the long propagation delay involved.

Question 11

Synchronization and interfacing techniques are sufficient by themselves.

Question 12

The beginning and end of each frame must be recognizable for effective communication between two directly connected transmitting-receiving stations.

Question 13

Only one frame may be in the pipe at a time with sliding-window flow control.

Question 14

The transmission medium between systems is referred to as a ________ when a data link control protocol is used.

A)data link
B)flow link
C)transmission link
D)control link

Question 15

DLHC is a widely used data link control.

Question 16

The initiation,maintenance,and termination of a sustained data exchange require management procedures for the exchange.

Question 17

The receiver must be able to distinguish control information from the data being transmitted.

Question 18

It is usually desirable to have a physically separate communications path for control information.

Question 19

It is necessary to impose a layer of control in each communicating device that provides functions such as flow control,error detection,and error control.

Question 20

The effect of ARQ is to turn an unreliable data link into a reliable one.

Question 21

In the high level data link control frame structure the flag,address,and control fields that precede the information field are known as a ________.

A)header
B)trailer
C)FAC
D)ARQ

Question 22

RR and RNR are examples of an ________.

A)error repair request
B)acknowledgment frame
C)open acknowledgment frame
D)interior window

Question 23

The flow control in which the destination can stop the flow of data simply by withholding acknowledgment of the receipt of a frame is ________ flow control

A)data
B)stop-and-wait
C)frame acknowledgment
D)ARQ

Question 24

In the HDLC frame structure the FCS and flag fields following the data field are referred to as a ________.

A)header
B)trailer
C)bit stuffing
D)information frames

Question 25

________ control refers to mechanisms that detect and correct errors that occur in the transmission of frames.

Question 26

_______ provide the ARQ mechanism in HDLC when piggybacking is not used.

A)I-frames
B)R-frames
C)U-frames
D)S-frames

Question 27

If two stations exchange data each needs to maintain two windows,one for transmit and one for receive,and each side needs to send the data and acknowledgments to the other.To provide efficient support for this requirement a feature known as ________ is typically provided.

Question 28

Most data link control protocols allow a station to cut off the flow of frames from the other side by sending a ________ message,which acknowledges former frames but forbids transfer of future frames.

Question 29

The flag field pattern is ________.

A)01111110
B)01111010
C)00111110
D)01111101

Question 30

Each ________ includes a field that holds the sequence number of that frame plus a field that holds the sequence number used for acknowledgment.

A)SAF
B)window
C)data frame
D)relay frame

Question 31

________ control is achieved by retransmission of damaged frames that have not been acknowledged or for which the other side requests a retransmission.

Question 32

The time it takes for a station to emit all of the bits of a frame onto the medium is the ________ time.

A)link
B)relay
C)propagation
D)transmission

Question 33

The form of flow control where a source entity transmits a frame and must wait until it receives an acknowledgment back from the destination entity before sending the next frame is ________ flow control.

Question 34

A technique for assuring that a transmitting entity does not overwhelm a receiving entity with data is ________.

Question 35

The form of flow control where A and B are connected via a full-duplex link and A maintains a list of sequence numbers that it is allowed to send without receiving any acknowledgment and B maintains a list of sequence numbers that it is prepared to receive is ________ flow control.

Question 36

The layer of control that provides error detection and error and flow control is known as a ________ protocol.

Question 37

A layer of logic is added above the physical layer to achieve necessary control.This logic is referred to as a ________ protocol.

Question 38

Containing virtually all of the features found in other data link control protocols,________ is a widely used data link control protocol.

Question 39

With ________ flow control the transmission link is treated as a pipeline that may be filled with frames in transit.

A)linking
B)sliding-window
C)ARQ
D)stop-and-wait

Question 40

The form of error control based on sliding-window flow control that is most commonly used is:

A)ACK-ARQ
B)selective-reject ARQ
C)go-back-N ARQ
D)piggybacking

Question 41

Since there is no assurance that the flag field pattern will not appear somewhere inside the frame,a procedure known as ________ is used to prevent destroying synchronization.

Question 42

An error detecting code calculated from the remaining bits of the frame, exclusive of flags,is the ________.

Question 43

With ________ ARQ the only frames retransmitted are those that receive a negative acknowledgment or those that time out.

Question 44

The most important data link control protocol is ________.

Question 45

High level data link control defines three types of frames,each with a different control field format.They are: information frames,unnumbered frames,and