Chapter 23: Data-link Protocols and Data Communications Networks – Review Notes

(Last Updated On: December 8, 2017)

Chapter 23: Data-link Protocols and Data Communications Networks

This is the summary notes of the important terms and concepts in Chapter 23 of the book "Electronic Communications System" by Wayne Tomasi. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.


CHAPTER 23

DATA-LINK PROTOCOLS AND
DATA COMMUNICATIONS NETWORKS


Items

Definitions

Terms

1

The primary goal of __________ is to give users of a network
the tools necessary for setting up the network and performing data flow
control.

Network Architecture

2

A set of rules implementing and governing an orderly exchange
of data between two layer devices.

Data-Link Protocol

3

The transmitting station in a data link protocol.

Master Station

4

The receiving station in a data link protocol.

Slave Station

5

Data link network wherein all stations have equal access to
the network.

Peer-to Peer Network

6

Discipline, Flow Control and Error Control.

Functions of Data-link Protocol

7

Coordinates hop-to-hop data delivery where a hop may be a
computer, a network controller, or some type of network-connecting device.

Line Discipline

8

Determines which device is transmitting and which is receiving
at any point in time.

Line Discipline

9

Coordinates the rate which data are transported over a link
and generally provides an acknowledgement mechanism.

Flow Control

10

Specifies means of detecting and correcting transmission
errors.

Error Control

11

Two fundamental ways that line discipline is accomplished in a
data communications network.

Enquiry/ Acknowledgement (ENQ/ACK) and
Poll/Select

12

It determines which device on the network can initiate a
transmission and whether the intended receiver is available and ready to
receive a message.

ENQ/ACK

13

The initiating station begins a session by transmitting a
frame, block, or packet of data called _________, which identifies the
receiving station.

Enquiry
(ENQ)

14

The response of the destination station when it is ready to
receive.

Positive Acknowledgement
(ACK)

15

The response of the destination station when it is not ready
to receive.

Negative Acknowledgement
(NAK)

16

The best application of the poll/select line discipline.

Centrally Controlled Data Network

17

A solicitation sent from the primary to a secondary to
determine if the secondary has data to transmit.

Poll

18

A set of procedures that tells the transmitting station how
much data it can send before it must stop transmitting and wait for an
acknowledgment from the destination station.

Flow Control

19

The transmitting station sends one message frame and then
waits for an acknowledgement before sending the next message frame.

Stop-and Wait Flow Control

20

A source station can transmit several frames in succession
before receiving an acknowledgement.

Sliding Window Flow Control

21

It refers to imaginary receptacles at the source and
destination stations with the capacity of holding several frames of data.

Sliding Window

22

Primary advantage of sliding window control.

Network Utilization

23

Primary disadvantages of sliding window flow control.

Complexity and Hardware Capacity

24

Interpret a frame of data as a group of successive bits
combined into predefined patterns of fixed length, usually eight bits each.

Character Oriented Protocols

25

Another name for character oriented protocols.

Byte-oriented Protocols

26

A discipline for serial by bit information transfer over a
data communications channel.

Bit Oriented Protocol

27

A character-oriented protocols generally used on two point
networks using asynchronous data and asynchronous modems.

Asynchronous Data link Protocols

28

Developed the first file transfer protocol designed to
facilitate transferring data between two personal computers in 1979.

Ward Christiansen

29

Cristiansen’s protocol which is relatively simple data link
protocol intended for lows-peed applications.

XMODEM

30

Remote stations can have more than one PC or printer.

Synchronous Data-Link Protocols

31

A group of computers, printers, and other digital devices.

Cluster

32

A synchronous character-oriented data link protocol developed
by IBM.

Binary Synchronous Communications
(BSC)

33

Another name for BSC.

Bisync

34

Another name for enquiry (ENQ) character.

Format or line turn around

35

The __________ uses longitudinal redundancy checking (LRC)
with ASCII coded messages and cyclic redundancy checking.

Block Check Character (BCC)

36

A synchronous bit oriented protocol developed in the 1970’s by
IBM for use in system network architecture environment.

Synchronous Data-Link Control
(SDLC)

37

Three transmission states.

Transient, Idle and Active

38

Flag Fields, Address Field, Control Field, Information and
Frame Check Sequence Field are __________.

SDLC Frame Fields

39

It is used for the delimiting sequence for the frame and to
achieve frame and character synchronization.

Flags

40

It is used for polling, confirming previously received frames,
and several other data link management functions.

Control Field

41

Three frame formats with SDLC.

Information, Supervisory and Unnumbered

42

A command or a response that is used to send unnumbered
information.

Unnumbered Information
(UI)

43

A command that places a secondary station into the
initialization mode.

Set Initialization Mode

44

A response sent by a secondary station to request the primary
to send a SIM command.

Request Initialization Mode
(RIM)

45

A command that places a secondary into the normal response
mode.

Set Normal Response Mode (SNRM)

46

A response transmitted from a secondary station if the primary
attempts to send numbered information frames to it when the secondary is in
the normal disconnect mode.

Disconnect Mode
(DM)

47

A response sent by a secondary when it wants the primary to
place it in the disconnect mode.

Request Disconnect
(RD)

48

An affirmative response that indicates compliance to SIM, SNRM
or DISC commands.

Unnumbered Acknowledgement

49

An exchange of frames between the primary station and a
secondary station.

TEST

50

A flag followed by eight consecutive logic 0’s.

Turnaround Sequence

51

A SDLC subcommand causes all previously set functions to be
cleared by the secondary.

Clear

52

A SLDC subcommand causes the secondary receiving it to turn on
or turn off its carrier.

Beacon Test

53

A SDLC command causes the addressed secondary station to pace
itself into the monitor mode.

Monitor Mode

54

A SDLC command causes a secondary station to loop its
transmission directly to its receiver input.

Wrap

55

A SDLC command causes the addressed secondary to initiate a
series of internal diagnostic tests.

Self-Test

56

The transparency mechanism used with SDLC.

Zero Bit Insertion or Zero Stuffing

57

It is used prematurely terminate an SDLC frame.

Message Abort

58

The encoding scheme used in SDLC.

Invert-On-Zero Coding

59

Standard that defines the frame structure, delimiting
sequence, transparency mechanism and error detection method used with HDLC.

ISO 3309

60

Operational Mode of SDLC.

Normal Response Mode
(NRM)

61

A mode of operation logically equivalent to a two point
private line circuit where each station has equal data link responsibilities.

Asynchronous Balanced Mode

62

A switched data communications network similar to the public
telephone network except a PDN is designed for transferring data only.

Public Switched Data Network
(PDN)

63

It is used when making a standard telephone call on the public
telephone network.

Circuit Switching

64

Is a form of store and forward network?

Message Switching

65

Another name for packet switching.

Hold and Forward Network

66

A user interface as the international standard for packet
network access.

X.25

67

SA logically equivalent to a two point dedicated private line
circuit except slower.

Permanent Virtual Circuit
(PVC)

68

A logically equivalent to making a telephone call through the
DDD network except no direct end to end connection is made.

Virtual Call

69

Identifies whether the packet is a new call request or a
previously established call.

Format Identifier

70

A 12 bit binary number that identifies the source and
destination users for a given virtual call.

Logical Channel Identifier

71

This four bit gives the number of digits that appear in the
calling address filed.

This four bit gives the number of digits
that appear in the calling address filed.

72

This field is the same as the calling address field except
that it identifies the number of digits that appear in the called address
field

Called Address Length

73

This field contains the destination address.

Called Address

74

This field is the same as the called address field except that
it contains up to 15 BCD.

Calling Address

75

This field identifies the number of eight bit octets present
in the facilities field.

Facilities Length Field

76

This 32 bit field is reserved for the subscriber to insert
user level protocol.

Protocol Identifier

77

A proposed network designed by the major telephone companies
in conjunction with the ITU-T.

Integrated Services Digital Network
(ISDN)

78

Customers gain access to the ISDN system through a local
interface connected to a digital transmission medium.

Digital Pipe

79

ISDN objectives that ensure universal access to the network.

System Standardization

80

Said objectives that allow customers to use a variety of
protocols and applications

Achieving Transparency

81

ISDN should not provide services that preclude competitiveness

Separating Functions

82

Provide private-line and switched services refer what objectives
of ISDN.

Variety of Configurations

83

ISDN services should not be directly related to cost and
independent of the nature of the data.

Addressing Cost-Related Tariffs

84

Provide a smooth transition while evolving.

Migration

85

Provide service to low capacity personal subscribers as well
as to large companies.

Multiplexed Support

86

Translation between non-ISDN data protocol and ISDN is
performed in this device.

Terminal Adapter

87

A boundary to the network and may be controlled by the ISDN
provider.

Network Termination 1

88

Refers to interfaces between the common carrier subscriber
loop and the central office switch.

U-Reference Point

89

The media interface point between an NT1 and the central
office.

U Loop

90

It is defined by ITU-T as a service that provides transmission
channels capable of supporting transmission rates greater than the primary
data rate.

Broadband ISDN

91

Information transfer is primarily from service provider to
subscriber

Distribution Services

92

Codes the data information into smaller packets used by the
BISDN network

Broadband Node

93

A connection between a source and a destination, which may
entail several ATM links.

Virtual Channel

94

Once data have entered the ATM network, they transferred into
fixed time slots called ________.

Cells

95

Controls the flow of traffic across the user network interface
(UNI) and into the network.

Generic Flow Control Field
(GFC)

96

The first three bits of the second half of byte 4 specify the
type of message in cell.

Payload Type Identifier

97

Information fields that are designed to accommodate PCM-TDM
traffic, which allows the ATM network to emulate voice or DSN services.

Constant Bit Rate

98

A portion of a public service provider’s switching system
where the service provider could be a local telephone company or a
long-distance carrier.

Public ATM Switches

99

Provides the most effective and economical means of handling
local data communications field.

Local Area Networks
(LAN)

100

A communications system that allows users to send messages to
each other through their computers.

E-Mails

101

LAN Topologies.

Star, Bus and Ring Topology

102

It describes how users access the communications channel in a
LAN.

Network Access Methodologies

103

Access method used primarily in bus topology.

CDMA/CD

104

It two stations transmit at the same time, ________ occurs.

Collision

105

The time it takes a signal to travel from a source to a
destination.

Propagation Delay

106

A base band transmission system designed in 1972 by Robert
Metcalfe and David Boggs.

Ethernet

107

Its purpose is to establish clock synchronization.

Preamble

108

It is simply a series of two logic 1’s appended to the end of
the preamble.

Start Frame Delimiter

109

Consists of six bytes that corresponds to the address of the
station sending the frame.

Source Address

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Chapter 23: Data-link Protocols and Data Communications Networks – Review Notes
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