Itm Lecture 3

INFORMATICS Information Technology Management

Lecture 3

27th December 2007 ITM Lecture 3 Advanced Diploma (Thames College)

1

Information o at o Tec Technology o ogy Management a age e t

Unitt 4: Methods U et ods of o Software So twa e Acquisition cqu s t o

ITM Lecture 3 Advanced Diploma (Thames College)

2

Evaluating Software Alternatives z

Examine E i software f alternatives l i and d select l an overall strategy for the proposed system to prepare for the transition to the systems design p phase.

ITM Lecture 3 Advanced Diploma (Thames College)

3

Custom Developed Software z

Some businesses consider that their processing requirements are specific to their own organization and they have the application software developed specifically. z In-house Development - Employing programmers and analysts and setting up an internal IT group. z Contract C an External E l Software S f - The Th company could ld use the h services of a computer bureau or software house, especially if it is a small organization which could not afford a fulltime development team. z The resultant software is known as Custom Custom-developed developed or Tailor-made Software since it exactly fits the requirements of the organization, just as a tailor-made suit exactly fits the purchaser. ITM Lecture 3 Advanced Diploma (Thames College)

4

Reasons for or In-House n House Developing (1) ( ) z Companies C i

choose h iin-house h p to: development Satisfy Unique Business Requirements z Minimize Mi i i Changes Ch iin B Business i P Procedures d and d Policies z Meet Constraints of Existing Systems z Meet Existing Technology z Develop Internal Resources and Capabilities z

ITM Lecture 3 Advanced Diploma (Thames College)

5

Reasons for In-House In House Developing (2) z Satisfy

Unique Business Requirements

z No

commercially available software package can meet their unique business requirements.

ITM Lecture 3 Advanced Diploma (Thames College)

6

Reasons for or In-House n House Developing (3) z Minimize Mi i i

Ch Chances iin B Business i P Procedures d and Policies While installing a new software package almost always requires some degree of change in how a company does business z If the installation of a purchased package will be too disruptive, then the organization might decide to develop its own software instead. z

ITM Lecture 3 Advanced Diploma (Thames College)

7

Reasons for or In-House n House Developing (4) z Meet M

C Constraints i off E Existing i i SSystems

z Any

new software installed must work with existing systems. z Ensure E that h the h new system will ill iinterface f with ih the old system.

ITM Lecture 3 Advanced Diploma (Thames College)

8

Reasons for or In-House n House Developing (5) z Meet M

C Constraints i off E Existing i i T Technology h l

z Another

reason to develop software in in-house house is that the new system must work with existing hardware and legacy systems systems.

ITM Lecture 3 Advanced Diploma (Thames College)

9

Reasons for or In-House n House Developing (6) z

Develop D l Internal I l Resources R andd C Capabilities bili i z Many y firms feel that in-house IT resources and capabilities provide a competitive advantage because they can respond quickly when business problems or opportunities arise. i

ITM Lecture 3 Advanced Diploma (Thames College)

10

Advantages of Custom Developed Software z The Th

advantages d off this hi type off applications li i software development p is that the resultant program will exactly fulfill the processing requirements. i

ITM Lecture 3 Advanced Diploma (Thames College)

11

Disadvantages of Custom Developed Software z Higher g z

Cost

The cost of producing tailor-made software is high, just as tailor-made clothing is expensive. This is because the costs off developing d l i the h software f are entirely i l borne b b by the one organization instead of them being borne by manyy organizations. g

z Software Defects z It is very y unusual for software to be perfect p when the programmers have finished. There is typically a period when the software is first operated where faults, or bugs, become exposed and have to be corrected corrected. This can often cause serious inconvenience to the end-user and, in terms of lost time and efficiency, increases the overall costt off the th software. ft ITM Lecture 3 Advanced Diploma (Thames College)

12

Custom Software

Figure 5.6 Advantages and disadvantages of custom applications ITM Lecture 3 Advanced Diploma (Thames College)

13

Purchasing a Software Package z

A commercially i ll available il bl software f package k could satisfy system requirements. Lower Cost z Less Time to Implement z Proven Reliability and Performance Benchmarks z Less L Technical T h i l Development D l Staff S ff z Future Upgrades Proved by the Vendor z Other Companies as Resources z

ITM Lecture 3 Advanced Diploma (Thames College)

14

Reasons for Package Purchasing (1) z Lower

Costs

z Because

many companies use software packages, software vendors spread the p costs over manyy customers. development

ITM Lecture 3 Advanced Diploma (Thames College)

15

Reasons for Package Purchasing (2) z

Less Time to Implement z

When you purchase a package, it already has been d i d programmed, designed, d tested, d andd ddocumented. d

ITM Lecture 3 Advanced Diploma (Thames College)

16

Reasons for Package Purchasing (3) zReasons R

for f Package P k Purchasing P h i

Proven Reliability and Performance Benchmarks z If the package has been on the market for any length g of time,, anyy major j problems p probably p y have already been detected and corrected by the vendor. z If the product is popular, popular it almost certainly has been rated and evaluated by independent reviewers. z

ITM Lecture 3 Advanced Diploma (Thames College)

17

Reasons for Package Purchasing (4) z Less L

Technical T h i l Development D l Staff S ff

z Companies

that use commercial software packages often are able to reduce the number of programmers and systems analysts on the IT staff.

ITM Lecture 3 Advanced Diploma (Thames College)

18

Reasons for Package g Purchasingg (5) ( ) z Future

Upgrades Provided by the Vendor

z Software

vendors regularly upgrade software packages by adding improvements andd enhancements h to create a new version i or release.

ITM Lecture 3 Advanced Diploma (Thames College)

19

Reasons for Package Purchasing (6) z Other Oh

C Companies i as R Resources

z Using

a commercial software package means you can contact users in other companies to get their impressions and input about the software package.

ITM Lecture 3 Advanced Diploma (Thames College)

20

Advantages g of Packaged g Software (1) ( ) z Lower

Cost z Less Software Defects z Better Documentation Do ment tion z Training g Easilyy Available

ITM Lecture 3 Advanced Diploma (Thames College)

21

Advantages g of Packaged g Software (2) ( ) z Lower

Cost

z The

most obvious and important advantage is that packages are significantly cheaper to p software. buyy than custom-developed z This is because package is sold to a large market k andd the h development d l costs can be b spread among a large number of purchasers.

ITM Lecture 3 Advanced Diploma (Thames College)

22

Advantages of Packaged Software (3) z

Less Software Defects Given the large market to which packages are sold, most off the h problems bl which hi h commonly l b beset new software have been ironed out prior to the i t d ti into introduction i t the th market k t place. l z It is good policy, however, to avoid pioneering by buying new software. z It is always better to purchase software that has been available for some time and will be well tried and tested. z

ITM Lecture 3 Advanced Diploma (Thames College)

23

Advantages g of Packaged g Software (4) ( ) z Better

Documentation

z Given

the scale of the applications package market, it is more feasible for the producers provide ggood documentation to to p accompany the software. z Clearly, Cl l this hi will ill make k the h package k easier i to use, which will make it more attractive to the market and therefore easier to sell. ITM Lecture 3 Advanced Diploma (Thames College)

24

Advantages of Packaged Software (5) z Training

Easily Available

z The

ease of use is also improved by the fact that it becomes viable for consultants and g to offer trainingg trainingg organizations courses in using it.

ITM Lecture 3 Advanced Diploma (Thames College)

25

Disadvantages g of Packaged g Software z

May not meet all requirements z

z

The facilities that are offered by a package are not as specific to a business as tailor tailor-made made software and might not quite satisfy the processing requirements of the business.

Less efficient z

Since the system is designed for more general purposes than the tailor-made software, the design may be less efficient. For example, a user may have to go through some unnecessary steps in processing which cannot be avoided. ITM Lecture 3 Advanced Diploma (Thames College)

26

Packaged Software

Figure 5.7 Advantages and disadvantages of packaged software ITM Lecture 3 Advanced Diploma (Thames College)

27

Customizing Software Packages z

Acquire A i a package k that h can b be customized i d to meet the needs of an organization. z

z

z

Purchase a basic package that vendor will customized to suit yyour needs Negotiate directly with the software vendor to make enhancements to meet your needs by paying extra charge Purchase the package and make your own modification. ITM Lecture 3 Advanced Diploma (Thames College)

28

Comparison

ITM Lecture 3 Advanced Diploma (Thames College)

29

Other Software Alternatives z Other Oh

possibilities ibili i iinclude l d using i an pp service p provider,, outsourcing, g, application and developing end-user applications. z Application A li i

SServices i Providers id z Outsourcing g z User Application

ITM Lecture 3 Advanced Diploma (Thames College)

30

Application Service Providers (ASP) z An A

ASP ddelivers li applications, li i or access to applications, by charging a usage or subscription fee. z An ASP provides more than a license to use the software; it rents an operational package k to the h customer. z The service that the ASP p provides is called Application Hosting. ITM Lecture 3 Advanced Diploma (Thames College)

31

Outsourcing z Outsourcing O i

iis the h use off outside id companies called Service Providers to handle a portion of a company's IT workloadd on a temporary w p y or long-term g basis. z Many M fi firms outsource IT workk as a way off controlling costs and dealing with rapid technological change. ITM Lecture 3 Advanced Diploma (Thames College)

32

User Applications z User

applications utilize standard business software, such as Microsoft Office, which h b has been configured fi d iin a specific ifi manner p y to enhance user productivity. z For

example, to help a sales respond rapidly to customer price requests, requests an IT support person can set up a form letter with links to a spreadsheet that calculates incentives and discounts. ITM Lecture 3 Advanced Diploma (Thames College)

33

Selecting a Software Alternative

ITM Lecture 3 Advanced Diploma (Thames College)

34

Steps in Evaluating and Purchasing Software Packages 1 1.

Evaluate the Information System Requirements a. Identify the Key Features of the system b E b. Estimate i V Volume l and dF Future G Growth h c. Specify any Hardware Constraints d. Prepare a Request for Proposal or Quotation

Identifyy Potential Software Vendors 3. Evaluate Software Package Alternatives 4 Make 4. M k th the P Purchase r h 5. Install the Software Package 2.

ITM Lecture 3 Advanced Diploma (Thames College)

35

Step 1: Evaluate the Information System Requirements z Based B d

on your analysis l i off the th system t q requirements, z Identify

the system's key features z Estimate E i volume l and d ffuture growth h z Specify p y anyy hardware constraints z Prepare a request for proposal or quotation

ITM Lecture 3 Advanced Diploma (Thames College)

36

Step 1a: Evaluate the Information System Requirements z Identify Id tif

The Th Key K Features F t off The Th System S t

z Evaluating g

system y requirements q involved highlighting any critical features the system must have. have

ITM Lecture 3 Advanced Diploma (Thames College)

37

Step 1b: Evaluate the Information System Requirements z Estimate E ti t

Volume V l andd Future F t Growth G th

z Know

the current volume of transactions and processing z Forecast changes over a three-to-five-year three to five year period.

ITM Lecture 3 Advanced Diploma (Thames College)

38

Step 1c: Evaluate the Information System Requirements z Specify S if

any Hardware H d C Constraints t i t

z The

software must run p properly p y on yyour current or proposed hardware platform.

ITM Lecture 3 Advanced Diploma (Thames College)

39

Step 1d: Evaluate the Information System Requirements z Prepare

a Request for Proposal or Quotation z Prepare

a Request for Proposal (RFP) or a q for Quotation Q (RFQ) ( Q) to obtain the Request information for making decision. z Request for proposal (RFP) is a written list of features and specifications given to prospective vendors when not identified a specific product or package to use. ITM Lecture 3 Advanced Diploma (Thames College)

40

Step 2: Identify Potential Software Vendors z The Th

nextt step t is i to t contact t t potential t ti l vendors. z Preparing an RFP will help the vendor's sales l representatives i identify id if possible ibl solutions. z Identify popular products and strategies by contacting i software f vendors, d industry i d sources,, and IT consultants. ITM Lecture 3 Advanced Diploma (Thames College)

41

Step 3: Evaluate Software Package Alternatives z

z

z

After identifying possible software packages, packages compare them and select one to fit the company's needs. needs Obtain information about the packages from as many sources as possible ibl ((vendor d presentations i andd literature, product documentation, trade publications), and companies that perform software testing and evaluation. Obtain information from existing users, test the application and benchmark the package if necessary. application, necessary ITM Lecture 3 Advanced Diploma (Thames College)

42

Step p 4: Make the Purchase z

z z

When you purchase software, software usually you do not own it - what you are buying is a software license that h gives i you the h right i h to use the h software f under d certain terms and conditions. Although most software packages are purchased, some vendors offer leasingg as a financial alternative. Another alternative is to investigate whether the package is available through an ASP for a rental of subscription fee. ITM Lecture 3 Advanced Diploma (Thames College)

43

Step p 5. Install the Software Package g After purchasing the software package, package the final step is installation. z Installation strategy should be planned well in advance, advance especially if any disruption of normal business operations is expected. expected z If the software package is customized, then the task will be more complex and difficult. difficult z Before the use of new software package, all implementation steps must complete, complete including loading, loading configuring, configuring and testing the software, training users; and converting data files to o thee new ew system's sys e s format. o a. z

ITM Lecture 3 Advanced Diploma (Thames College)

44

Information o at o Tec Technology o ogy Management a age e t

Unit 5: Data Networks Network

Source

Destination ITM Lecture 3 Advanced Diploma (Thames College)

45

Digital Representation of Information Input

Numbers & Text

Process 000001100 000001000 ---------------000010100

12 + 8 = 20

20

0010000000000000000 0100000000000001001 0110000011000011011 0111111111111001111 1111111111111011111 1111111111100011111

Images

Sound

Output

p pitch, , volume 8 9 20 7 8 19 5 6 15

time

000001000 000001001 000010100 .....

Video

001010101110010101011100101010111 110101010101101010101011010101010 010101010100101010101001010101010 111101000111111010001111110100011 001010110110010101101100101011011 00101010111 00101010111 11010101010 11010101010 01010101010 01010101010 11110100011 11110100011 00101011011 00101011011

ITM Lecture 3 Advanced Diploma (Thames College)

46

Network Transmission Media z

Electricity: Twisted pair, coaxial cable z Light: Fiber optics z Radio waves

Fib Optic Fiber O ti Cable C bl

Ex. of twisted pair: Ex Local phone lines

Radio or Micro Waves Example: Cellular phones

Coaxial cable

antenna

Example: Shield Cable TV ITM Lecture 3 Advanced Diploma (Thames College)

47

Computer p Communications z

Process in which one computer transfers data, data instructions, instructions and information to another computer(s) Communications system contains many types of devices a) Personal P l

computers b) Notebook computers p c) Web-enabled cellular telephones d) Web-enabled Web enabled handheld computers e) WebTV™ f) GPS G S receivers i

ITM Lecture 3 Advanced Diploma (Thames College)

48

What is needed for Successful Communications?

ITM Lecture 3 Advanced Diploma (Thames College)

49

Data Networks zA

Network is a communications system on which computers transfer and share data andd resources z It is a collection of computers and devices connected together via communications devices such as modems, modems cables, cables telephone lines and satellites that allow user to share resources ITM Lecture 3 Advanced Diploma (Thames College)

50

Simplified Network Model

ITM Lecture 3 Advanced Diploma (Thames College)

51

Computer p Networks And Data Communications

ITM Lecture 3 Advanced Diploma (Thames College)

52

Local Area Network (LAN) ( ) z z z z

A cluster of interconnected microcomputers forming a network U ll carry ddata at hi Usually high h speeds d & owned db by one Originated g as a description of size Cover a small Cove s a local oca area

ITM Lecture 3 Advanced Diploma (Thames College)

53

Facilities of LAN zA

variety i off ffacilities ili i are required to enable networks to function. function zFile

Server zP Printt Server Se ve zCommunications Server ITM Lecture 3 Advanced Diploma (Thames College)

54

Facilities of LAN - File Server z Facilitates F ilit t

the th storage t off documents d t which hi h p as necessary. y can be retrieved and updated z Enable network users to access application software f install i ll in i one file fil server z Enable user access control

ITM Lecture 3 Advanced Diploma (Thames College)

55

Facilities of LAN - Print Server z Provides P id

each h network t k user with ith highhi h p p printingg facilities. speed

ITM Lecture 3 Advanced Diploma (Thames College)

56

Facilities of LAN - Communications Server z Links Li k

network t k users to t a variety i t off p line communication devices byy telephone connections.

ITM Lecture 3 Advanced Diploma (Thames College)

57

Client / Server LAN z Network N t rk

in which hi h one n orr m more r computers mp t r actt as a server and other computers on the network can request services from server

ITM Lecture 3 Advanced Diploma (Thames College)

58

Internet use of Peer-to-Peer (P2P) ( ) z Enables E bl

users with ith same networking t ki software to connect to each other's hard disks and exchange files directly

ITM Lecture 3 Advanced Diploma (Thames College)

59

Advantages g of Data Networks z The Th

advantages d t off networks t k are as follow: f ll

z Sharing g

Hardware z Sharing Software z Sharing Sh i D Data z Electronic Mail

ITM Lecture 3 Advanced Diploma (Thames College)

60

Advantages of Data Networks Sharing Hardware z Networking N t ki

severall microcomputers i t g alongg with one printer, p for together example, can allow all the computers to use the one printer. printer z Since few users have to use the p printer all of the time, this represents a more efficient method of employing this resource. resource ITM Lecture 3 Advanced Diploma (Thames College)

61

Advantages of Data Networks Sharing Hardware zA

network t k off computers t can allow ll severall pp software users to make use of applications which is stored on one of the machines. z When Wh this hi method h d iis employed, l d the h machine which holds the software is called a fileserver.

ITM Lecture 3 Advanced Diploma (Thames College)

62

Advantages of Data Networks Sharing Data z Similar Si il

use can b be made d off th the data d t files fil created byy the users. z This can eliminate the requirement for multiple l i l copies i off the h data d files fil to be b maintained,, therebyy improving p g data integrity.

ITM Lecture 3 Advanced Diploma (Thames College)

63

Advantages of Data Networks Electronic Mail z This Thi

ffacility ilit is i only l possible ibl iin a network t k g configuration.

ITM Lecture 3 Advanced Diploma (Thames College)

64

Wide Area Network (WAN) ( ) z Network N t k

that th t covers large l geographic hi area z Internet is world world'ss largest WAN

ITM Lecture 3 Advanced Diploma (Thames College)

65

Wide Area Network (WAN) ( ) z

z

z

Whereas a local area network serves the requirements of an organization for p communications, a wide area interdepartmental network serves a wide geographic area and may in fact embrace a whole country or even the world. The IEEE (Institute of Electrical and Electronics Engineers) formally recognizes as local networks those networks having a maximum total length of 6000 feet. Beyond that length, networks are classified as WANs. Another definition of WANs is that they simply g connect two or more LANs together ITM Lecture 3 Advanced Diploma (Thames College)

66

What is Internet? z

z

Internet is an electronic communications network that connects computer networks and organizational computer facilities around the world. world It is a Network of computers that links Businesses, G Government agencies, i IInstitutions i i and d IIndividual di id l users together

ITM Lecture 3 Advanced Diploma (Thames College)

67

LAN vs WAN z

A Local Area Network (LAN) is a computer network limited to the immediate area, usually the same building or floor of a building. LANs are capable of transmitting data at very fast rates, t muchh faster f t than th the th data d t that th t is i transmitted t itt d to t you over the Internet; there is no limit on the number of computers that g LAN. can be attached to a single

z

A Wide Area Network (WAN) is a computer network covering a wide geographical area, involving a vast array of computers.

z

This is different from LANs that are usually limited to a room, room building or campus. The most well-known example of a WAN is the Internet. ITM Lecture 3 Advanced Diploma (Thames College)

68

Public Industryy Network z

Public Industry Network is a telecommunications network designed for open, public access.

z

Generically, it is a network operated by common carriers or telecommunications administrations for the provision of circuit-switched, packet-switched, andd leased-line l d li circuits i it to t the th public. p bli

z

Internet is a interconnecting global public network made by connecting smaller shared public networks. ITM Lecture 3 Advanced Diploma (Thames College)

69

Virtual Private Network (VPN) ( ) z

Virtual Private Network (VPN) is a data network that uses the public telecommunications infrastructure but maintains privacy through the infrastructure, use of a tunneling protocol and security procedures.

z

A VPN gives a company the same capabilities as a system of owned or leased lines to which that company has exclusive access. But costs are much lower because the VPN uses the shared public infrastructure rather than exclusive line access. ITM Lecture 3 Advanced Diploma (Thames College)

70

Value Added Network (VAN) ( ) z z

z

Value Added Network (VAN) is a privately owned, or proprietary, network. VAN generally provide specialized services, services such as electronic data interchange services or access to a particular database database. There are many options available for a VAN, by d fi iti a VAN adds definition, dd something thi off value l to t the th transmission. z

For example, l the h service i purchased h db by traditional di i l EDI D users that electronically communicates EDI transactions between Trading Partners on a demand basis basis. ITM Lecture 3 Advanced Diploma (Thames College)

71

Example p of VAN Services z

z

Value-Added Value Added Network (VAN) vendors are organizations that provide service to the public over common carrier facilities facilities. A good example of a service provided by VAN is environmental information retrieval. z z

There are also information retrieval firms that specialize in certain types of market data in specific industries. A corporation may subscribe to one more of these services in order that employees such as marketing managers and sales forecasters may obtain up-to-date up to date industry information. ITM Lecture 3 Advanced Diploma (Thames College)

72

Primary Function of a Communications Device z To T

convert digital di i l signals i l to analog l signals i l or analogg signals g to digital g signals g

ITM Lecture 3 Advanced Diploma (Thames College)

73

Factorss to Consider Facto Co s de z When Wh

considering id i a L Locall A Area N Networkk ((LAN), ), there are several factors to consider. z This will result in a better configuration andd a better b utilization off the networkk p capabilities. z Utilization z Performance z Flexibility ITM Lecture 3 Advanced Diploma (Thames College)

74

Factors to Consider - Utilization The number Th b off current and d ffuture users must be b known or estimated. z Different choices in cabling, structure (topology) and hardware will determine the performance levels given certain number of users. z If there are too many users relative to the p of the LAN, then the p performance capabilities will deteriorate. z

ITM Lecture 3 Advanced Diploma (Thames College)

75

Factors to Consider - Performance z The Th

expectedd response time i andd storage capacity p y must be determined in order to be able to specify the correct components and it true its tr cost. t

ITM Lecture 3 Advanced Diploma (Thames College)

76

Factors to Consider - Flexibility z The Th

ease with i h which hi h new users can b be added or removed from a system y is important to the organization. z Certain configurations f allow for f a limitedd number of new PCs to be added,, after which costly expansion work has to be done. ITM Lecture 3 Advanced Diploma (Thames College)

77

Network Topology z Configuration, C fi i

or physical h i l arrangement, off devices in a communications network z Networks usually use combinations of three topologies z Bus

Network z Ring Network z Star Network ITM Lecture 3 Advanced Diploma (Thames College)

78

Bus Network Consists C i off a single i l centrall cable, bl to which hi h allll computers and other devices connect z Bus is physical cable or backbone z Inexpensive and easy to install z

ITM Lecture 3 Advanced Diploma (Thames College)

79

Star Network All ddevices i connect to a centrall computer, called ll d the hub z All data transferred from one computer to another passes through hub z

ITM Lecture 3 Advanced Diploma (Thames College)

80

Ring Network Cable C bl fforms closed l d ring, i or lloop, with i h allll computers and devices arranged along ring z Data travels from device to device around entire ring in one direction ring, z

ITM Lecture 3 Advanced Diploma (Thames College)

81

Sendingg a Request q over the Internet Sending device requests information 2. When request q leaves the ISP,, it travels over a variety of lines until it reaches Internet backbone 3. Request travels over T3 lines alongg Internet backbone 4. Request travels over T1 li lines until til it reaches h destination network server 1 1.

router server

workstation mobile

local ISP

regional ISP

company network

ITM Lecture 3 Advanced Diploma (Thames College)

82

Information o at o Tec Technology o ogy Management a age e t

U i 66: T Unit Telecommunications l i i Equipment

ITM Lecture 3 Advanced Diploma (Thames College)

83

Telecommunication Equipment z Businesses B i

needd to t be b able bl to t communicate i t g or with data either within the organization other business partners. z A small ll computerized i d system switch i h the h public line to anyy one of the internal phone p p lines z Make M k connection i b between the h extension i public line and the p ITM Lecture 3 Advanced Diploma (Thames College)

84

Telephone p z Both B h

vocall ddata andd electronic l i communication of encoded data z Voice converted to analog electrical signals z Signal carried via electrical cable to a switching office then switch onto correct cables to reach the correct telephone

ITM Lecture 3 Advanced Diploma (Thames College)

85

Private Automated Branch Exchange (PABX) z The

Private Automatic Branch Exchange (PABX) is a small computerized system which controls the switching of extension lines with each other and with the p public system. y z The operator only need to enter the required extension number and the PABX will make the connection between the extension and the public line. z It enable a few p public exchange line to be shared amongst many in i the h organization i i

ITM Lecture 3 Advanced Diploma (Thames College)

86

Facilities for PABX z

The PABX also has other facilities which can be programmed in by users. z

z

z z

When a call is not answered,, the PABX can direct call to all the extensions in the same department. If there is still no answer, then the call can be redirected back to the telephonist p at the switchboard. w b Users can program a series of commonly used numbers into a memory so they can be dialed by pressing just one or two keys instead of the whole number. number If somebody going to spend some time in another office, he can redirect their calls to the temporarily office. When sharing an office, punching a short code will cause the call to be transferred to the user's own desk. ITM Lecture 3 Advanced Diploma (Thames College)

87

Voice Services (Voice Mail) z Enables

a caller's caller s spoken message to be recorded in a digital form in a 'voice mail box' z User can access the message by phone and the message is converted back into voice z Cheap but only one way

ITM Lecture 3 Advanced Diploma (Thames College)

88

Tele-Facsimile Tele Facsimile (FAX) z To

send an exact copy of an original document including text and graphics to other fax subscribers z Reliable, fast and cheap z Used U d ttelephone l h lilines ITM Lecture 3 Advanced Diploma (Thames College)

89

Other Facilities z When

calls to an extension not answered, answered PABX can direct the call to another line, calls can also be redirected to the telephonist z Memory of commonly used number for quick qu c dial da z Temporarily redirect calls to another extension t i z Enable p pick up p of another extension's call ITM Lecture 3 Advanced Diploma (Thames College)

90

Public Switched Telephone Network (PSTN) z Worldwide

telephone system that handles voice-oriented

ITM Lecture 3 Advanced Diploma (Thames College)

91

Telex Both sender and recipient must have telex terminal z Data can be typed directly into telex terminal z Confirmation that the message has been received z

ITM Lecture 3 Advanced Diploma (Thames College)

92

Dial-up Dial up Modem Communications device that converts computer's digital signals to analog signals and analog signals to digital signals z ISDN and DSL use digital modem with a digital t l ph telephone liline z

ITM Lecture 3 Advanced Diploma (Thames College)

93

Cable Modem z Modem

that sends and receives data over cable television network z Much faster than modem or ISDN z Usually attaches to network card

ITM Lecture 3 Advanced Diploma (Thames College)

94

Communicating with Anyone

ITM Lecture 3 Advanced Diploma (Thames College)

95

Local Area Network (LAN) z

Highh speed, Hi d data d networkk over small region z Few thousand meters z Network technologies: z Ethernet z FDDI z Token ring g z Data link layer z Packets routed based on physical address

LAN 1

LAN 2 ITM Lecture 3 Advanced Diploma (Thames College)

96

Connecting Below Internet Level z

Hub z Center of star topology z In Ethernet, multiport repeater or concentrator z Bridge z Connects 2 networks of same technology h l – extended d d LAN A z Filters/forwards/floods based on MAC z Link layer - frames z Switch z Connects 2+ networks – packet-switched network z Reduces collisions

Hub

Bridge

CISCOSYSTEMS

CISCOSYSTEMS

CISCOSYSTEMS

Switch

ITM Lecture 3 Advanced Diploma (Thames College)

97

Connecting at the Internet nternet Level z

Router z Originally gateway z Forwards packets based on network layer info (IP) z Separate broadcast domains z In each domain, IP packet encapsulated in domain-specific packet

CISCOSYSTEMS

CISCOSYSTEMS

Router

ITM Lecture 3 Advanced Diploma (Thames College)

CISCOSYSTEMS

98

Network Interface Card (NIC) z

Card inserted into expansion slot of personal computer or other device, enabling it to connect to a network

ITM Lecture 3 Advanced Diploma (Thames College)

99

Hub z Device

that provides a central point for cables in a network

ITM Lecture 3 Advanced Diploma (Thames College)

100

Physical Transmission Media z

Wire, cable, Wire cable and other tangible (touchable) materials used to send communications signals

ITM Lecture 3 Advanced Diploma (Thames College)

101

Twisted-pair Twisted pair cable z Transmission

media used by telephone system and network cabling

ITM Lecture 3 Advanced Diploma (Thames College)

102

Coaxial Cable z Single

copper wire surrounded by at least three layers z Often used for cable television wiring

ITM Lecture 3 Advanced Diploma (Thames College)

103

Fiber-Optic Fiber Optic Cable z Contains

core of dozens or hundreds of thin strands of glass or plastic z Uses light to transmit signals

ITM Lecture 3 Advanced Diploma (Thames College)

104

Wireless Transmission Media Send communications signals through air or space z Used when inconvenient, inconvenient impractical impractical, or impossible to install cables z

ITM Lecture 3 Advanced Diploma (Thames College)

105

Questions & Discussion

ITM Lecture 3 Advanced Diploma (Thames College)

106