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.
The primary goal of __________ is to give users of a network
the tools necessary for setting up the network and performing data flow
A set of rules implementing and governing an orderly exchange
of data between two layer devices.
The transmitting station in a data link protocol.
The receiving station in a data link protocol.
Data link network wherein all stations have equal access to
Peer-to Peer Network
Discipline, Flow Control and Error Control.
Functions of Data-link Protocol
Coordinates hop-to-hop data delivery where a hop may be a
computer, a network controller, or some type of network-connecting device.
Determines which device is transmitting and which is receiving
at any point in time.
Coordinates the rate which data are transported over a link
and generally provides an acknowledgement mechanism.
Specifies means of detecting and correcting transmission
Two fundamental ways that line discipline is accomplished in a
data communications network.
Enquiry/ Acknowledgement (ENQ/ACK) and
It determines which device on the network can initiate a
transmission and whether the intended receiver is available and ready to
receive a message.
The initiating station begins a session by transmitting a
frame, block, or packet of data called _________, which identifies the
The response of the destination station when it is ready to
The response of the destination station when it is not ready
The best application of the poll/select line discipline.
Centrally Controlled Data Network
A solicitation sent from the primary to a secondary to
determine if the secondary has data to transmit.
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.
The transmitting station sends one message frame and then
waits for an acknowledgement before sending the next message frame.
Stop-and Wait Flow Control
A source station can transmit several frames in succession
before receiving an acknowledgement.
Sliding Window Flow Control
It refers to imaginary receptacles at the source and
destination stations with the capacity of holding several frames of data.
Primary advantage of sliding window control.
Primary disadvantages of sliding window flow control.
Complexity and Hardware Capacity
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
Another name for character oriented protocols.
A discipline for serial by bit information transfer over a
data communications channel.
Bit Oriented Protocol
A character-oriented protocols generally used on two point
networks using asynchronous data and asynchronous modems.
Asynchronous Data link Protocols
Developed the first file transfer protocol designed to
facilitate transferring data between two personal computers in 1979.
Cristiansen’s protocol which is relatively simple data link
protocol intended for lows-peed applications.
Remote stations can have more than one PC or printer.
Synchronous Data-Link Protocols
A group of computers, printers, and other digital devices.
A synchronous character-oriented data link protocol developed
Binary Synchronous Communications
Another name for BSC.
Another name for enquiry (ENQ) character.
Format or line turn around
The __________ uses longitudinal redundancy checking (LRC)
with ASCII coded messages and cyclic redundancy checking.
Block Check Character (BCC)
A synchronous bit oriented protocol developed in the 1970’s by
IBM for use in system network architecture environment.
Synchronous Data-Link Control
Three transmission states.
Transient, Idle and Active
Flag Fields, Address Field, Control Field, Information and
Frame Check Sequence Field are __________.
SDLC Frame Fields
It is used for the delimiting sequence for the frame and to
achieve frame and character synchronization.
It is used for polling, confirming previously received frames,
and several other data link management functions.
Three frame formats with SDLC.
Information, Supervisory and Unnumbered
A command or a response that is used to send unnumbered
A command that places a secondary station into the
Set Initialization Mode
A response sent by a secondary station to request the primary
to send a SIM command.
Request Initialization Mode
A command that places a secondary into the normal response
Set Normal Response Mode (SNRM)
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.
A response sent by a secondary when it wants the primary to
place it in the disconnect mode.
An affirmative response that indicates compliance to SIM, SNRM
or DISC commands.
An exchange of frames between the primary station and a
A flag followed by eight consecutive logic 0’s.
A SDLC subcommand causes all previously set functions to be
cleared by the secondary.
A SLDC subcommand causes the secondary receiving it to turn on
or turn off its carrier.
A SDLC command causes the addressed secondary station to pace
itself into the monitor mode.
A SDLC command causes a secondary station to loop its
transmission directly to its receiver input.
A SDLC command causes the addressed secondary to initiate a
series of internal diagnostic tests.
The transparency mechanism used with SDLC.
Zero Bit Insertion or Zero Stuffing
It is used prematurely terminate an SDLC frame.
The encoding scheme used in SDLC.
Standard that defines the frame structure, delimiting
sequence, transparency mechanism and error detection method used with HDLC.
Operational Mode of SDLC.
Normal Response Mode
A mode of operation logically equivalent to a two point
private line circuit where each station has equal data link responsibilities.
Asynchronous Balanced Mode
A switched data communications network similar to the public
telephone network except a PDN is designed for transferring data only.
Public Switched Data Network
It is used when making a standard telephone call on the public
Is a form of store and forward network?
Another name for packet switching.
Hold and Forward Network
A user interface as the international standard for packet
SA logically equivalent to a two point dedicated private line
circuit except slower.
Permanent Virtual Circuit
A logically equivalent to making a telephone call through the
DDD network except no direct end to end connection is made.
Identifies whether the packet is a new call request or a
previously established call.
A 12 bit binary number that identifies the source and
destination users for a given virtual call.
Logical Channel Identifier
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.
This field is the same as the calling address field except
that it identifies the number of digits that appear in the called address
Called Address Length
This field contains the destination address.
This field is the same as the called address field except that
it contains up to 15 BCD.
This field identifies the number of eight bit octets present
in the facilities field.
Facilities Length Field
This 32 bit field is reserved for the subscriber to insert
user level protocol.
A proposed network designed by the major telephone companies
in conjunction with the ITU-T.
Integrated Services Digital Network
Customers gain access to the ISDN system through a local
interface connected to a digital transmission medium.
ISDN objectives that ensure universal access to the network.
Said objectives that allow customers to use a variety of
protocols and applications
ISDN should not provide services that preclude competitiveness
Provide private-line and switched services refer what objectives
Variety of Configurations
ISDN services should not be directly related to cost and
independent of the nature of the data.
Addressing Cost-Related Tariffs
Provide a smooth transition while evolving.
Provide service to low capacity personal subscribers as well
as to large companies.
Translation between non-ISDN data protocol and ISDN is
performed in this device.
A boundary to the network and may be controlled by the ISDN
Network Termination 1
Refers to interfaces between the common carrier subscriber
loop and the central office switch.
The media interface point between an NT1 and the central
It is defined by ITU-T as a service that provides transmission
channels capable of supporting transmission rates greater than the primary
Information transfer is primarily from service provider to
Codes the data information into smaller packets used by the
A connection between a source and a destination, which may
entail several ATM links.
Once data have entered the ATM network, they transferred into
fixed time slots called ________.
Controls the flow of traffic across the user network interface
(UNI) and into the network.
Generic Flow Control Field
The first three bits of the second half of byte 4 specify the
type of message in cell.
Payload Type Identifier
Information fields that are designed to accommodate PCM-TDM
traffic, which allows the ATM network to emulate voice or DSN services.
Constant Bit Rate
A portion of a public service provider’s switching system
where the service provider could be a local telephone company or a
Public ATM Switches
Provides the most effective and economical means of handling
local data communications field.
Local Area Networks
A communications system that allows users to send messages to
each other through their computers.
Star, Bus and Ring Topology
It describes how users access the communications channel in a
Network Access Methodologies
Access method used primarily in bus topology.
It two stations transmit at the same time, ________ occurs.
The time it takes a signal to travel from a source to a
A base band transmission system designed in 1972 by Robert
Metcalfe and David Boggs.
Its purpose is to establish clock synchronization.
It is simply a series of two logic 1’s appended to the end of
Start Frame Delimiter
Consists of six bytes that corresponds to the address of the
station sending the frame.