L7- Building Telecommunication System (Part 2)

Question 1

Most of the lines in the telephone systems of the world at present are _______. Signals are transmitted as continuous waves. This is a satisfactory way to transmit voice.

Answer 1

Analog

Question 2

The conversion of data from digital form into analog for transmission and then back into digital at the receiving end is done by a pair of interface devices
called

Answer 2

modems (modulator-demodulator)

Question 3

Modem-based telecommunications have created a significant bottleneck in an environment where computer and peripheral speeds have increased dramatically. The solution is end-to-end __________ communications, in which signals are sent as streams of on/off pulses.

Answer 3

digital

Question 4

Digital lines are capable of much faster communication and ______________ is now cheaper than analog. All the new equipment now installed in telephone networks is indeed digital.

Answer 4

digital circuitry

Question 5

Trend: There is a shift toward digital telecommunications is taking place throughout the world. A digital system for telecommunications, called _____________, is in wide use in parts of the telephone network.

Answer 5

TI carrier

Question 6

Future: ________________ - a completely digital telecommunications network standardized by an international committee.

Answer 6

Integrated Services Digital Network (ISDN)

Question 7

With the geographical distribution of information systems, increased volumes of transmission, and the move to multimedia, the costs of telecommunications are a significant business concern. Two principal
methods of reducing these costs are:

Answer 7

1. Multiplexing - the sharing of a high-capacity link by a number of transmissions
2. Signal Compression - using the link more efficiently by removing redundancies from the signal.

Question 8

Many individual transmissions can share a physical channel through a variety of techniques collectively called ______________. It combines several lower-capacity transmissions into a single transmission, which is split at the receiving end.

Answer 8

Multiplexing

Question 9

It is the reduction of the need for channel capacity by
removing redundancies from the signal.

Answer 9

Signal compression

Question 10

________________ differ in scope from relatively slow wide area networks, employed to transmit messages across vast geographic distances, to very fast local area networks that may connect computers located in the same building.

Answer 10

Computer networks

Question 11

Computers, switches, and terminals interconnected by network links are collectively called _____

Answer 11

nodes

Question 12

The purpose of network control is to provide a connection between nodes that need to communicate. The arrangement of nodes and links in a network is called a ______

Answer 12

topology

Question 13

The following network topologies are the most widely used:

Answer 13

1. Hierarchical Network
2. Star Network
3. Ring Network
4. Bus Network

Question 14

This topology matches the organizational structure of
many firms and is still frequently used in WANs. The user workstations may be, in turn, interconnected
using one of the LAN topologies.

Answer 14

Hierarchical Network

Question 14

In this topology, a hub computer or switch (such as a PBX) interconnects a number of workstations. . The computer at the hub acts as the network server, providing access to the shared database and software. All communications between the workstations must go through this central mode.

Answer 14

Star Network

Question 15

The nodes are usually close to one another;
this topology is frequently used in LANs. When one node sends a message to another, the message passes through each intermediate node, which restores the signal, as signals deteriorate in transmission.

Answer 15

Ring Network

Question 16

The nodes are connected to a common link such as
coaxial cable. This arrangement is used in LANs. A failing device does not affect the rest of the network.

Answer 16

Bus Network

Question 17

Principal techniques for switching include:

Answer 17

1. Circuit Switching
2. Packet Switching
3. Fast Packet Switching

Question 18

It is a technique employed in a telephone network. Communication links are connected to switching centers, which connect to one node to another on demand. It is suitable for file transfers and similar longer transmissions.

Answer 18

Circuit switching

Question 19

It is of particular importance for data communication
owing to its speed and its superior utilization of communication links when handling Abursty,@ intermittent, traffic. Indeed, data transmission involves short bursts of activity by a computer or a terminal when the data are sent, followed by long periods when
there is no transmission.

It offers flexibility in connecting to a network. It is
used by most of the public data networks provided by value-added carriers.

Answer 19

Packet switching

Question 20

In packet switching, messages are divided at the source into fixed-length chunks, called ___________, that also include bits identifying the receiver. Typically, a packet contains 128 bytes of data.

Answer 20

packets

Question 21

Traditional packet switching checks each packet for errors at every node the packet passes through. Modern telecommunications equipment is far more
noise-free than that for which packet switching was originally designed.

Answer 21

Fast Packet Switching

Question 22

There are two fast packet-switching technologies being
introduced:

Answer 22

1. Frame Relay
2. Cell Relay (asynchronous transfer mode, or ATM)

Question 23

Fast packet switching that checks a packet for errors only at the entry and exit nodes of the telecommunications network, thus reducing transmission delay.

Answer 23

Frame Relay

Question 24

Fast packet switching that transfers very short fixed-length packets, called cells, over fast LANs or WANs.

Answer 24

Cell Relay

Question 25

Communication rules, called _______________, enable dissimilar hardware and software to communicate over a single network. All the nodes in the network must follow a set of rules.

Answer 25

protocols

Question 26

International Standards Organization (ISO) has developed the OSI model in order to organizing protocols. The _______________ opens the field to a broad array of competing vendors, a situation that benefits users to ensure that they are not locked into a closed, proprietary protocol structure of a specific manufacturer.

Answer 26

open system approach

Question 27

OSI Layer and Function: 1. _____________ provides access to the telecommunications medium and ensures transmission of the bit stream over it.

Answer 27

Physical

Question 28

OSI Layer and Function: 2. ____________ ensures error-free transmission of frames (blocks) of data over a network link.

Answer 28

Data Link

Question 29

OSI Layer and Function: 3. ____________ routes messages (or packets) from source to destination by selecting connecting links.

Answer 29

Network

Question 30

OSI Layer and Function: 4. ____________ provides reliable end-to-end connection between two communicating nodes. When packet switching is used this layer breaks a message into packets.

Answer 30

Transport

Question 31

OSI Layer and Function: 5. ______________ establishes, maintains, and terminates a connection (session) between two applications running on communicating nodes. A session lasts, for example, from a long-on to a specific application to a log-off.

Answer 31

Session

Question 32

OSI Layer and Function: 6. _____________ provides any necessary conversions of the character being sent (encryption/decryption, compression/decompression, or character code conversions). Issue requests for establishing and terminating a session to the session layer.

Answer 32

Presentation

Question 33

OSI Layer and Function: 7. ____________ provides services to communicating application programs; examples include file transfer, running a remote program, allocating a remote peripheral, and ensuring integrity of remote databases.

Answer 33

Application

Question 34

Two protocol sets have gained importance:

Answer 34

1. SNA - IBM's Systems Network Architecture - its functions are broken down into five layers, basically performing the functions of the five middle OSI levels. 2. TCP/IP - Transmission Control Protocol/Internet Protocol - its functions are broken down into five layers. TCP provides the higher-level services in connecting the communicating applications, while IP ensures the lower-level functions of routing and addressing, guiding the packets over the Internet

Question 35

Interconnection between two networks of the same type is accomplished by a relatively simple ________, implemented in hardware and software.

Answer 35

bridge

Question 36

Interconnection between dissimilar networks, for example, a LAN and a WAN, is achieved through a more complex _________. It is is a device that accepts messages in the format produced by one of the networks and translates them into the format used by the other.

Answer 36

router

Question 37

Characteristics of a LAN include:

Answer 37

1. Its scope is commonly measured in feet 2. Communication speeds are very high 3. Used as a local means of computing and communication among users in larger firms 4. Are owned by the organization 5. Afford a sense of control and the flexibility to meet the demands of the end users

Question 38

There are two principal LAN designs:

Answer 38

1. Peer-to-peer - peripherals are located at terminals and system administration is largely left up to the users 2. Server-based networks - shared resources are placed a dedicated server that manage a given resource on behalf of user workstations sharing the resource (file server, printer server, gateway, optical disk server).

Question 39

A company with a large number of telephones (from 50 to over 10,000) often elects to own a computer-based ____________, an electronic switchboard that interconnects its telephones and provides connections to the public network.

Answer 39

private branch exchange (PBX)