gITEC45

Question 1

We can synchronize the sending and receiving nodes so that the receiving node always knows when a new character is being sent or we can insert within the bit stream special “start” and “stop” bits.

Answer 1

Asynchronous Serial Transmission

Question 2

used to convey clock (timing) information, this method group’s data together into a sequence of bits (five­-eight), then prefixes them with a start bit and a stop bit.

Answer 2

Asynchronous Serial Transmission

Question 3

these used motors driving cams which actuated solenoids which sampled the signal at specific time intervals.

Answer 3

Asynchronous Serial Transmission

Question 4

Asynchronous systems send data bytes between the sender and receiver.

Answer 4

Asynchronous Protocols

Question 5

Each data byte is preceded with a start bit, and suffixed with a stop bit. These extra bits serve to synchronize the receiver with the sender.

Answer 5

Asynchronous Protocols

Question 6

Transmission of these extra bits (2 per byte) reduce data throughput

Answer 6

Asynchronous Protocols

Question 7

Asynchronous protocols are suited for low speed data communications.

Answer 7

Asynchronous Protocols

Question 8

the line idle state is changed to a known character sequence (7E).

Answer 8

Synchronous Serial Transmission

Question 9

is used to synchronize the receiver to the sender.

Answer 9

Synchronous Serial Transmission

Question 10

The start and stop bits are removed, and each character is combined with others into a data packet

Answer 10

Synchronous Serial Transmission

Question 11

The data packet is prefixed with a header field, and suffixed with a trailer field which includes a checksum value (used by the receiver to check for errors in sending).

Answer 11

Synchronous Serial Transmission

Question 12

involve sending timing information along with the data bytes, so that the receiver can remain in synchronization with the sender.

Answer 12

Synchronous Protocols

Question 13

Data bytes are packaged into small chunks called packets, with address fields being added at the front (header) and checksums at the rear of the packet
There are two main types of sync

Answer 13

Synchronous Protocols

Question 14

Most communication systems have started with point to­ point links which directly connect together the users wishing to communicate using a dedicated communication circuits.

Answer 14

Switching

Question 15

As the distance between users increases beyond the length of the cable, the connection between the users was formed by a number of sections which were connected end ­to­ end in series to form the circuit.

Answer 15

Switching

Question 16

For a point­ to­ point circuit, (also known as a
________ _____) the nodes are patch panels which provide a simple connection between the two links (i.e., the two transmission circuits).

Answer 16

permanent circuit

Question 17

As the number of connected users increased, it has become infeasible to provide a circuit which connects every user to every other user, and some sharing of the transmission circuits (known as “switching”) has become necessary.

Answer 17

Switching

Question 18

is a set of connected devices.

Answer 18

Network

Question 19

is a set of nodes that are interconnected to permit the exchange of information.

Answer 19

Network

Question 20

is a collection of computers, servers, mainframes, network devices, peripherals, or other devices connected to one another to allow the sharing of data.

Answer 20

Switching

Question 21

is either a redistribution point or a communication endpoint.

Answer 21

Nodes

Question 22

any system or device connected to a network is also called a ____.

Answer 22

Node

Question 23

consists of a series of interlinked nodes, called switches.

Answer 23

Switched Network

Question 24

is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device.

Answer 24

Switches

Question 25

is a multiport network bridge that uses MAC addresses to forward data at the data link layer of the OSI model.

Answer 25

switches

Question 26

are devices capable of creating temporary connections between two or more devices linked to the switch. In a switched network, some of these nodes are connected to the end systems.

Answer 26

Switches

Question 27

Many characteristics of switched communication networks are directly dependent on how data is relayed over the wires.

Answer 27

Packet Switching

Question 28

Early networks carried continuous bitstreams over physical links in a technique called ______ _______, well suited to transmit voice or real time data from a single sender to a single receiver (unicast communication).

Answer 28

circuit switching

Question 29

is the term used to describe communication where a piece of information is sent from one point to another point.

Answer 29

Unicast`

Question 30

in which a packet is sent from a single source to a specified destination, is still the predominant form of transmission on LANs and within the Internet.

Answer 30

Unicast transmission

Question 31

A physical link failure in circuit switching networks has dramatic consequences leading to the interruption of all communications using the failed link.

Answer 31

Packet Switching

Question 32

Datagram packet switching networks like the Internet, fix these drawbacks by cutting data into small chunks called ______

Answer 32

Packets

Question 33

switching networks, two consecutive packets from the same communication are independently handled by the network.

Answer 33

Datagram packet

Question 34

is a cross between a circuit-switched network and a datagram network. It is normally implemented in the data link layer, while a circuit-switched network is implemented in the physical layer and a datagram network in the network layer.

Answer 34

Virtual-circuit network

Question 35

is collection of data that can be used by computers which need to communicate with each other, usually as part of a network.

Answer 35

Packets

Question 36

is the unit of data that is routed between an origin and a destination on the Internet or any other packet-switched network.

Answer 36

Packets

Question 37

consists of control information and user data, which is also known as the _______

Answer 37

payload

Question 38

is the most familiar technique used to build a communication network.

Answer 38

Circuit Switching 

Question 39

it is used for ordinary telephone calls.

Answer 39

Circuit Switching

Question 40

it allows communications equipment and circuits, to be shared among users. Each user has sole access to a circuit (functionally equivalent to a pair of copper wires) during network use.

Answer 40

Circuit Switching

Question 41

consists of a set of switches connected by physical links.

Answer 41

Circuit Switching

Question 42

a connection between two stations is a dedicated path made of one or more links.

Answer 42

Circuit Switching

Question 43

is made of a set of switches connected by physical links, in which each link is divided into n channels.

Answer 43

Circuit Switching

Question 44

a dedicated circuit is established between a sender and a receiver, and the signals coming from one end are transmitted to the other.

Answer 44

Circuit Switching

Question 45

this connection is maintained for as long as both parties desire, after which it is closed. The drawback is that if a large part of a conversation consists of silence, the line carrying the conversation is effectively idle for most of the time.

Answer 45

Circuit Switching

Question 46

receives the connection request and identifies a path to the destination (D) via an intermediate node (C).

Answer 46

Node B

Question 47

This problem is considerably aggravated for digital signals, which are sent in _________ ______ rather than continuously.

Answer 47

staccato bursts

Question 48

were used for phone calls and packet-switched networks handled data. But because of the reach of phone lines and the efficiency and low cost of data networks, the two technologies have shared chores for years.

Answer 48

Circuit Switching

Question 49

Before the two parties (or multiple parties in a conference call) can communicate, a dedicated circuit (combination of channels in links) needs to be established.

Answer 49

setup phase

Question 50

The end systems are normally connected through dedicated lines to the switches, so connection setup means creating dedicated channels between the switches.

Answer 50

Setup Phase

Question 51

When system A needs to connect to system M, it sends a setup request that includes the address of system M, to switch I. Switch I finds a channel between itself and switch IV that can be dedicated for this purpose. Switch I then sends the request to switch IV, which finds a dedicated channel between itself and switch III. Switch III informs system M of system A's intention at this time.

Answer 51

Setup phase

Question 52

After the establishment of the dedicated circuit (channels), the two parties can transfer data.

Answer 52

Date transfer phase

Question 53

When one of the parties needs to disconnect, a signal is sent to each switch to release the resources.

Answer 53

Teardown Phase

Question 54

are not as efficient as the other types of networks because resources are allocated during the entire duration of the connection.

Answer 54

efficiency

Question 55

these resources are unavailable to other connections. In a telephone network, people normally terminate the communication when they have finished their conversation.

Answer 55

efficiency

Question 56

in computer networks, a computer can be connected to another computer even if there is no activity for a long time. In this case, allowing resources to be dedicated means that other connections are deprived.

Answer 56

effficiency

Question 57

the delay in this type of network is minimal.

Answer 57

delay

Question 58

during data transfer the data are not delayed at each switch; the resources are allocated for the duration of the connection

Answer 58

Delay

Question 59

the paths in the circuit are separated from one another spatially. This technology was originally designed for use in analog networks but is used currently in both analog and digital networks. It has evolved through a long history of many designs.

Answer 59

Space-Division Switch

Question 60

connects n inputs to m outputs in a grid, using electronic microswitches (transistors) at each cross point.

Answer 60

Crossbar Switch

Question 61

which combines crossbar switches in several (normally three) stages

Answer 61

Multistage Switch

Question 62

uses time-division multiplexing (TDM) inside a switch.

Answer 62

Time-Division Switch

Question 63

TDM stands for

Answer 63

Time-Division Switch

Question 64

The most popular technology is called the____ ____ __________

Answer 64

time-slot interchange

Question 65

TSI stands for

Answer 65

Time-slot Interchange

Question 66

is most often used for data communication.

Answer 66

Packet Swtich

Question 67

is similar to message switching using short messages. Any message exceeding a network­ defined maximum length is broken up into shorter units, known as _____

Answer 67

packets

Question 68

break streams of data into smaller blocks of data. Each of these small blocks are then sent independently over a shared network.

Answer 68

Packet Switching

Question 69

most networks consist of many links which allow more than one path through the network between nodes.

Answer 69

Packet Switching

Question 70

allows users to equally share bandwidth resources but makes no promises concerning quality or latency.

Answer 70

Packet Switching

Question 71

is easier and more affordable than circuit switching.

Answer 71

Packet Switching

Question 72

networks move data in separate, small blocks -- packets -- based on the destination address in each packet. When received, packets are reassembled in the proper sequence to make up the message.

Answer 72

Packet Switching

Question 73

it provides the basis for traditional telephone networks.

Answer 73

Packet Switching

Question 74

performs the physical and data link functions of the packet switch. The bits are constructed from the received signal. The packet is decapsulated from the frame.

Answer 74

Input ports

Question 75

Errors are detected and corrected

Answer 75

inputs ports

Question 76

performs the same functions as the input port, but in the reverse order.

Answer 76

Output Ports

Question 77

performs the functions of the network layer.

Answer 77

Routing processors

Question 78

This activity is sometimes referred to as _____ _____ because the routing processor searches the routing table.

Answer 78

table lookup

Question 79

The most difficult task in a packet switch is to move the packet from the input queue to the output queue. The speed with which this is done affects the size of the input/output queue and the overall delay in packet delivery.

Answer 79

Switching Fabrics

Question 80

is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link. As data and telecommunications use increases, so does traffic.

Answer 80

Multiplexing

Question 81

is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource.

Answer 81

Multiplexing

Question 82

multiplexers and de-multiplexers are used to convert multiple signals into one signal. This term is also known as ______

Answer 82

muxing

Question 83

is a technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency bands, each of which is used to carry a separate signal.

Answer 83

Frequency-Division multiplexing(FDM)

Question 84

FDM stands for

Answer 84

Frequency-Division Multiplexing

Question 85

is designed to use the high-data-rate capability of fiber-optic cable. The optical fiber data rate is higher than the data rate of metallic transmission cable. Using a fiber-optic cable for one single line wastes the available bandwidth.

Answer 85

Wavelength-Division Multiplexing (WDM)

Question 86

WDM stands for

Answer 86

Wavelength-Division Multiplexing