Information Systems and Technologies

Information Systems and Technologies

WHY INFORMATION SYSTEMS ARE IMPORTANT

An understanding of the effective and responsible use and management of information systems is important for managers and other business knowledge workers in today’s global information society. Information systems and technologies have become a vital component of successful businesses and organizations. Information systems constitute an essential field of study in business administration and management, as they are considered a major functional area in business operations.

WHAT YOU NEED TO KNOW

Managerial end users need to know how information systems can be employed successfully in a business environment. The important question for any business end user or manager is: What do you need to know in order to help manage the hardware, software, data, and network resources of your business, so they are used for the strategic success of your company?

An IS Framework for Business Professionals:
Managers or business professionals are not required to know the complex technologies, abstract behavioral concepts, or the specialized applications involved in the field of information systems. Figure below illustrates a useful conceptual framework that outlines what a manager or business professional needs to know about information systems. It emphasizes five areas of knowledge:
• Foundation Concepts
• Information Technologies
• Business Applications
• Development Processes
• Management Challenges



What is an Information System?
An information system (IS) can be any organized combination of people, hardware, software, communications networks, and data resources that collect, transforms, and disseminate information in an organization.

Information Technologies:
Business professionals rely on many types of information systems that use a variety of information technologies. For example:

Types of IS - Manual (paper-and-pencil) information systems
- Informal (word-of-mouth) information systems
- Formal (written procedures) information systems
- Computer-based information systems

Computer-based information systems (IS) use hardware, software, the Internet, and other telecommunications networks, computer-based data resource management techniques, and other forms of information technologies (IT) to transform data resources into a variety of information products for consumers and business professionals.

SYSTEM CONCEPTS

System concepts underlie the field of information systems. Understanding system concepts will help you understand many other concepts in the technology, applications, development, and management of information systems. System concepts help you understand:
• Technology. That computer networks are systems of information processing components that uses a variety of hardware, software, data and telecommunication technologies.
• Applications. That electronic business and commerce involves interconnected business information systems.
• Development. That developing ways to use information technology n business includes designing the basic components of information systems.
• Management. That managing information technology emphasizes the quality, strategic business value, and security of an organization’s information systems.

What is a System?
Question: What is a system as it applies to the concept of an information system?

Answer: A system is a group of interrelated components working together toward a common goal by accepting inputs and producing outputs in an organized transformation process.

A system (sometimes called a dynamic system) has three basic interacting components or functions. These include:
• Input involves capturing and assembling elements that enter the system to be processed.
• Processing involves transformation processes that convert input into output.
• Output involves transferring elements that have been produced by a transformation process to their ultimate destination.

Feedback and Control:
Two additional components of the system concept include feedback and control. A system with feedback and control components is sometimes called a cybernetic system, that is, a self-monitoring, self-regulating system.
• Feedback is data about the performance of a system.
• Control involves monitoring and evaluating feedback to determine whether a system is moving toward the achievement of its goals. The control function then makes necessary adjustments to a system's input and processing components to ensure that it produces proper output.

Other System Characteristics:
A system does not exist in a vacuum; rather, it exists and functions in an environment containing other systems.

Subsystem: A system that is a component of a larger system, where the larger system is its environment.

System Boundary: A system is separated from its environment and other systems by its system boundary.

Interface: Several systems may share the same environment. Some of these systems may be connected to one another by means of a shared boundary, or interface.

Open System: A system that interacts with other systems in its environment is called an open system (connected to its environment by exchanges of inputs and outputs).

Adaptive System: A system that has the ability to change itself or its environment in order to survive is called an adaptive system.


COMPONENTS OF AN INFORMATION SYSTEM

An information system model expresses a fundamental conceptual framework for the major components and activities of information systems. An information system depends on the resources of people, hardware, software, data, and networks to perform input, processing, output, storage, and control activities that convert data resources into information products.

The information systems model outlined in the text emphasizes four major concepts that can be applied to all types of information systems:
• People, hardware, software, data, and networks, are the five basic resources of information systems.
• People resources include end users and IS specialists, hardware resources consist of machines and media, software resources include both programs and procedures, data resources can include data and knowledge bases, and network resources include communications media and networks.
• Data resources are transformed by information processing activities into a variety of information products for end users.
• Information processing consists of input, processing, output, storage, and control activities.

INFORMATION SYSTEM RESOURCES

The basic IS model shows that an information system consists of five major resources:
• People resources
• Hardware resources
• Software resources
• Data resources
• Network resources

People Resources:
People are required for the operation of all information systems. These people resources include end users and IS specialists.
• End Users (also called users or clients) are people who use an information system or the information it produces. Most of us are information system end users. And most end users in business are knowledge workers, that is, people who spend most of their time communicating and collaborating in teams of workgroups and creating, using, and distributing information.
• IS Specialists are people who develop and operate information systems. They include system analysts, software developers, system operators, and other managerial, technical, and clerical IS personnel.

Systems analysts – design information systems based on the information requirements of end users.
Software developers – create computer programs based on the specifications of systems analysts.
System operators – monitor and operate large computer systems and networks.

Hardware Resources:
Hardware resources include all physical devices and materials used in information processing.
• Machines - physical devices (computers, peripherals, telecommunications networks, etc.)
• Media - all tangible objects on which data are recorded (paper, magnetic disks etc.)

Examples of hardware in computer-based information systems are:
• Computer Systems – which consist of central processing units containing microprocessors, and a variety of interconnected peripheral devices.
• Computer peripherals – which are devices such as a keyboard or electronic mouse for input of data and commands, a video screen or printer for output of information, and magnetic or optical disks for storage of data resources.

Software Resources:
Software resources include all sets of information processing instructions.
• Program - a set of instructions that causes a computer to perform a particular task.
• Procedures - set of instructions used by people to complete a task.


Examples of software resources are:
• System software – such as an operating system program, that controls and supports the operations of a computer system.
• Application software – are programs that direct processing for a particular use of computers by end users.
• Procedures – are operating instructions for the people who will use an information system.

Data Resources:
Data constitutes a valuable organizational resource. Thus, data resources must be managed effectively to benefit all end users in an organization. The data resources of information systems are typically organized into:
• Databases - a collection of logically related records or files. A database consolidates many records previously stored in separate files so that a common pool of data records serves many applications.
• Knowledge Bases - which hold knowledge in a variety of forms such as facts and rules of inference about various subjects.

Data versus Information. The word data is the plural of datum, though data is commonly used to represent both singular and plural forms. The term’s data and information are often used interchangeably. However, you should make the following distinction:

Data: - are raw facts or observations, typically about physical phenomena or business transactions. More specifically, data are objective measurements of the attributes (characteristics) of entities, such as people, places, things, and events.

Information: - is processed data, which has been placed in a meaningful and useful context for an end user. Data is subjected to a “value-added” process (data processing or information processing) where:
• Its form is aggregated, manipulated, and organized.
• Its content is analyzed and evaluated
• It is placed in a proper context for a human user

Network Resources:
Telecommunications networks like the Internet, intranets, and extranets have become essential to the successful electronic business and commerce operations of all types of organizations and their computer-based information systems. Telecommunications networks consist of computers, communications processors, and other devices interconnected by communications media and controlled by communications software. The concept of network resources emphasizes that communications networks are a fundamental resource component of all information systems. Network resources include:
• Communications media (twisted-pair wire, coaxial cable, fiber-optic cable, and microwave, cellular, and satellite wireless systems.
• Network support (people, hardware, software, and data resources that directly support the operation and use of a communications network).



INFORMATION SYSTEM ACTIVITIES

Information processing (or data processing) activities that occur in information system include the following:
• Input of data resources
• Processing of data into information
• Output of information products
• Storage of data resources
• Control of system performance


Input of Data Resources:
• Data about business transactions and other events must be captured and prepared for processing by the input activity. Input typically takes the form of data entry activities such as recording and editing.
• Once entered, data may be transferred onto a machine-readable medium such as magnetic disk or type, until needed for processing.

Processing of Data into Information:
• Data is typically subjected to processing activities such as calculating, comparing, sorting, classifying, and summarizing. These activities organize, analyze, and manipulate data, thus converting them into information for end users.
• A continual process of correcting and updating activities must maintain quality of data stored in an information system.

Output of Information Products:
• Information in various forms is transmitted to end-users and made available to them in the output activity. The goal of information systems is the production of appropriate information products for end users.

Storage of Data Resources:
Storage is a basic system component of information systems.
• Storage is the information system activity in which data and information are retained in an organized manner for later use.

Control of System Performance:
An important information system activity is the control of its performance.
• An information system should produce feedback about its input, processing, output, and storage activities.
• Feedback must be monitored and evaluated to determine if the system is meeting established performance standards.
• Feedback is used to make adjustments to system activities to correct deficiencies.


RECOGNIZING INFORMATION SYSTEMS

As a business professional, you should be able to recognize the fundamental components of information systems you encounter in the real world. This means that you should be able to identify:
• The people, hardware, software, data, and network resources they use.
• The types of information products they produce.
• The way they perform input, processing, output, storage, and control activities.

Analysing BellSouth’s Information System
From the Real World Case of BellSouth Corporation, we will try to recognize or visualize the resources used, activities performed, and information products produced by their information systems.

IS Resources:
• People resources include end users like BellSouth’s online customers and employees, and IS specialists like CIO Fran Dramis and project leader Lori Groves.

Hardware Resources:
• Thousands of PC server
• Other computers that BellSouth and its customers must be using

Software Resources:
• Web browsers
• Operating systems
• e-commerce websites software
• Oracle’s customer relationship management system
• Other proprietary BellSouth business software.

Network Resources:
• Communications media and network support components that are part of the network resources that BellSouth would need to support the e-business and e-commerce activities of such a large telecommunications company.
Data Resources:
• Computer-accessible databases of data about their customers, employees, services, and other necessary business information.

Information Products:
• Displays on customer and employee networked PCs that provide information about and support the provision of BellSouth’s services, such as you would find by visiting their Websites at www.bellsouth.com and www.bellsouthcorp.com.

IS Activities:
• Input activities include the input of Web site navigation clicks and e-commerce and e-business data entries and selections, and online collaboration queries and responses made by customers, suppliers, and employees.

Processing Activities:
• Processing activities are accomplished whenever any of BellSouth’s computers executes the programs that are part of their e-business and e-commerce software resources.

Output Activities:
• Output activities primarily involve the display or printing of information products mentioned earlier.

Storage Activities:
• Storage activities take place whenever business data is stored and managed in the files and databases on the disk drives and other storage media of BellSouth’s computer systems.

Control Activities:
• Control activities include the use of passwords and other security codes by customers, suppliers, and employees for entry into BellSouth’s e-business and e-commerce websites, and access of their databases and knowledge bases.


Section II: Foundation Concepts: Business Applications, Development, and Management

THE FUNDAMENTAL ROLES OF IS APPLICATIONS IN BUSINESS

Information systems perform three vital roles in any type of organization. That is, they support an organization’s:
• Business processes and operations
• Decision making by employees and managers
• Strategies for competitive advantage

The Major Roles of IS: Examples

Three major roles of the business applications of information systems include:
• Support Business Processes – involves dealing with information systems that support the business processes and operations in a business.
• Support Decision Making – help decision makers to make better decisions and attempt to gain a competitive advantage.
• Support Competitive Advantage – help decision makers to gain a strategic advantage over competitors requires innovative use of information technology.



e-BUSINESS IN BUSINESS

The explosive growth of the Internet and related technologies and applications is revolutionizing the way businesses are operated and people work, and how information technology supports business operations and end user work activities.

e-business is defined as the use of Internet technologies to internetwork and empower business processes, electronic commerce, and enterprise communication and collaboration within a company and with its customers, suppliers, and other business stakeholders.

Enterprise collaboration systems involve the use of groupware tools to support communication, coordination, and collaboration among the members of networked teams and workgroups. An internetworked e-business enterprise depends on intranets, the Internet, extranets, and other networks to implement such systems.

Electronic commerce is the buying and selling, and marketing and servicing of products, services, and information over a variety of computer networks. An internetworked e-business enterprise uses the Internet, intranets, extranets, and other networks to support every step of the commercial process.



TRENDS IN INFORMATION SYSTEMS

The roles given to the information systems function have expanded significantly over the years.

1950s - 1960s - Data Processing - Electronic data processing systems
Role: Transaction processing, record keeping, and accounting, and other electronic data processing (EDP) applications

1960s - 1970s - Management Reporting – Management information systems
Role: Providing managerial end users with predefined management reports that would give managers the information they needed for decision-making purposes.

1970s - 1980s - Decision Support - Decision support systems
Role: The new role for information systems was to provide managerial end users with ad hoc support of their decision-making process. This support would be tailored to the unique decision-making styles of managers as they confronted specific types of problems in the real world.

1980s - 1990s - Strategic and End User Support
Role: End users could use their own computing resources to support their job requirements instead of waiting for the indirect support of corporate information services departments.
• End User Computing Systems
Role: Direct computing support for end user productivity and work group collaboration.

• Executive Information Systems (EIS) -
Role: These information systems attempt to give top executives an easy way to get the critical information they want, when they want it, tailored to the formats they prefer.

• Expert Systems (ES) and other Knowledge-Based Systems
Role: Expert systems can serve as consultants to users by providing expert advice in limited subject areas.

• Strategic Information Systems (SIS)
Role: Information technology becomes an integral component of business processes, products, and services that help a company gain a competitive advantage in the global marketplace.

1990s - 2000 – Electronic business and commerce systems
Role: The rapid growth of the Internet, intranets, extranets, and other interconnected global networks has revolutionising the operations and management of today’s business enterprises.

Foundations of Information Systems in Business

Foundations of Information Systems in Business

Importance of Information Systems – An understanding of the effective and responsible use and management of information systems and technologies is important for managers, business professionals, and other knowledge workers in today’s internetworked enterprises. Information systems play a vital role in the e-business and e-commerce operations, enterprise collaboration and management, and strategic success of businesses that must operate in an internetworked global environment. Thus, the field of information systems has become a major functional area of business administration.

An IS Framework for Business Professionals – The IS knowledge that a business manager or professional needs to know includes (1) foundation concepts: fundamental behavior, technical, business, and managerial concepts like system components and functions, or competitive strategies; (2) information technologies: concepts, developments, or management issues regarding hardware, software, data management, networks, and other technologies; (3) business applications: major uses of IT for business processes, operations, decision making, and strategic/competitive advantage; (4) development processes: how end users and IS specialists develop and implement business/IT solutions to problems and opportunities arising in business; and (5) management challenges: how to effectively and ethically manage the IS function and IT resources to achieve top performance and business value in support of the business strategies of the enterprise.

System Concepts – A system is a group of interrelated components working toward the attainment of a common goal by accepting inputs and producing outputs in an organized transformation process. Feedback is data about the performance of a system. Control is the component that monitors and evaluates feedback and makes any necessary adjustments to the input and processing components to ensure that proper output is produced.

An Information System Model – An information system uses the resources of people, hardware, software, data, and networks to perform input, processing, output, storage, and control activities that convert data resources into information products. Data are first collected and converted to a form that is suitable for processing (input). Then the data are manipulated and converted into information (processing), stored for future use (storage), or communicated to their ultimate user (output) according to correct processing procedures (control).

IS Resources and Products - Hardware resources include machines and media used in information processing. Software resources include computerized instructions (programs) and instruction for people (procedures). People resources include information systems specialists and users. Data resources include alphanumeric, text, image, video, audio, and other forms of data. Network resources include communications media and network support. Information products produced by an information system can take a variety of forms, including paper reports, visual displays, multimedia documents, electronic messages, graphics images, and audio responses.

Business Applications of Information Systems - Information systems perform three vital roles in business firms. Business applications of IS support an organization’s business processes and operations, business decision-making, and strategic competitive advantage. Major application categories of information systems include operations support systems, such as transaction processing systems, process control systems, and enterprise collaboration systems, and management support systems, such as management information systems, decision support systems, and executive information systems. Other major categories are expert systems, knowledge management systems, strategic information systems, and functional business systems. However, in the real world most application categories are combined into cross-functional information systems that provide information and support for decision-making and also perform operational information processing activities.

Six Sigma

What is Six Sigma?

Six Sigma is several things.

It is basically a Philosophy, an outlook or a way that we perceive and work with in the business world around us.
Essentially, the philosophy is of working smarter, not harder. It is also Statistical Measurement. It tells us how good our
• Products
• Services
• Processes

It translates to making fewer and fewer mistakes in everything we do.

Six Sigma has
• Well-defined project charter that outlines the scope of a project
• Financial targets
• Anticipated benefits
• Milestones, etc
It is based on hard financial data and savings.

Historical Overview:

Six Sigma was originally developed as a set of practices designed to improve manufacturing processes and eliminate defects, but its application was subsequently extended to other types of business processes as well.
In Six Sigma, a defect is defined as anything that could lead to customer dissatisfaction.
The particulars of the methodology were first formulated by Bill Smith at Motorola in 1986.

Six Sigma’s Specialties:

The Six Sigma method allows us to draw comparisons to other similar or dissimilar products. In this manner we can see how far ahead or behind we are. Most importantly, we see where we need to go and what we must do to get there.

How dose Six Sigma affects?

Six sigma as a business strategy can greatly help us to gain competitive edge. As we improve the sigma rating of a process, the product quality/ service quality improves and costs go down and customer becomes more satisfied.

Effectiveness of Six Sigma:

Six Sigma provides a structured data-driven methodology with tools and techniques that companies can use to measure their performance both before and after Six Sigma projects.

What Management can do using Six Sigma?

Using Six Sigma, Management can
• Measure the baseline performance of their processes
• Determine the root causes of variations so, they can improve their processes to meet and exceed the desired performance levels

What Managers can do using Six Sigma?

Six Sigma allows Managers to take their projects to
• New levels of discipline
• Comprehensive commitment

For standard project management ideas, you can approach them ad-hoc and implement them as you learn them.

Six Sigma’s Key Methods:

Six Sigma has two key methods:
1. DMAIC (Design-Measure-Analysis-Improve-Control)
2. DMADV (Define-Measure-Analyze-Design-Verify)
3.
Sigma levels:

Short term sigma levels correspond to the following long-term DPMO (Defective Parts Per Million Opportunities) values.

• One Sigma = 690,000 DPMO = 31% efficiency
• Two Sigma = 308,000 DPMO = 69.2% efficiency
• Three Sigma = 66,800 DPMO = 93.32%efficiency
• Four Sigma = 6,210 DPMO = 99.379% efficiency
• Five Sigma = 230 DPMO = 99.977% efficiency
• Six Sigma = 3.4 DPMO = 99.9997% efficiency

Why DMAIC and DMADV are used?


• DMAIC is used to improve an existing business process.
• DMADV is used to create new product or process designs

DMAIC:

The basic method consists of the following five steps:
1. Define process improvement goals that are consistent with customer demands and the enterprise strategy.
2. Measure key aspects of the current process and collect relevant data.
3. Analyze the data to verify cause-and-effect relationships. Determine what the relationships are, and attempt to ensure that all factors have been considered.
4. Improve or optimize the process based upon data analysis using techniques like Design of experiments.
5. Control to ensure that any deviations from target are corrected before they result in defects.

DMADV:

The basic method consists of the following five steps:
1. Define design goals that are consistent with customer demands and the enterprise strategy.
2. Measure and identify CTQs (characteristics that are Critical To Quality), product capabilities, production process capability, and risks.
3. Analyze to develop and design alternatives, create a high-level design and evaluate design capability to select the best design.
4. Design details, optimize the design, and plan for design verification. This phase may require simulations.
5. Verify the design, set up pilot runs, implement the production process and hand it over to the process owners.

DMADV is also known as DFSS, an abbreviation of "Design For Six Sigma".

Success Granted by Six Sigma:

This success is accomplished by means of
• understanding what the methodology is?
• how it is applied?
• and how it used?

There are many challenges facing by Project Managers:

• Data gathering and Analysis
• Problem solving
• Understanding and Evaluating existing processes
• Developing and tracking measurements in a standardized manner
• Making quantitative evaluations.

Six Sigma methodology provides tools and techniques to help a manager be successful in all of these challenges.

BASICS OF NETWORKING

BASICS OF NETWORKING

Networking is connecting two or more devices to allow communication between them with the purpose of sharing information and resources. Examples of these devices are computers, printers, routers, hubs, modems, and PDAs. The information and resources being shared can be anything from MS Office documents and e-mail to printers and fax devices. Internetworking is connecting multiple networks with the purpose of creating one large network. The Internet is the most common example of an internetwork.

Client/server vs Peer-to-peer

Most of today's networks use the client/server model. In this model at least one computer acts as a server. Servers hold resources that are accessed over the network by clients. Examples of resources are shared files, e-mail messages and even applications. Another common server is the print server that allows access to network printers.
In a peer-to-peer network model every computer can act as a client and a server at the same time. An example is a network with 4 Windows XP Professional computers in a workgroup using file and print sharing.

LAN/WAN

The terms LAN and WAN mainly refer to the geographical area of the network. LAN is short for Local Area Network and is a high-speed network typically within a building. WAN is short for Wide Area Network and refers to low-speed networks that cover a large distance, for example a network that spans several cities or the entire globe even. The Internet can be considered the largest WAN, but actually consists of many different WANs, which, in turn, include LANs. The connection between LANs in an internetwork is also referred to as a WAN connection, although a network diagram of a WAN often includes the LANs in it.

Private vs Public Networks

Two other terms used to categorize networks are private networks and public networks. A private network is typically within the premises of a corporation and can be accessed only by users working for, or related to, that corporation. A public network Internet can be accessed by multiple individuals and/or corporations, the best example of a public network is again, the Internet.

Media

The physical connection used to transport electrical signals (bits; 1s & 0s) between the network devices is called the media. Examples of network media are copper cabling, fiber optic cabling and infra-red.

Protocols

To be able to communicate with each other, network devices need a common language. The language network devices use is called a protocol. There are many different types of protocols available, and most protocols are actually a suite of several protocols, each with a different function. For example, one protocol allows data transfer between hosts and another can be used to retrieve email from a mail server.

Addressing

If you want to contact somebody by snail-mail or by telephone you need some sort of address. In a telephone network you need to enter a telephone number to reach your intended communication partner. Similar, devices in a network need an address. There are two types of addresses, the first type is configured in software by a network administrator and uses protocols to define the addressing scheme and format, this type is known as network or layer 3 addressing. The other type of address that devices in a network use, is most commonly referred to as MAC address; this address is burned into the chip of the physical network interface.

Network Topologies

A physical topology depicts how network devices are connected physically, the cabling.
A logical topology depicts the route a the signal takes on the network.
Collisions

A collision indicates that two or more network nodes have tried to access the network simultaneously, and both put a signal on the network cable at the same time which collide with each other. Occasional occurrences are normal and will not affect network performance.

Access Methods

The access method defines how signals are put on the network media.
Carrier Sense Multiple Access with Collision Detection (CSMA/CD) The access method used in Ethernet networks. In so called broadcast networks multiple nodes are attached to the same cable segment. To avoid that nodes on the network transmit traffic simultaneously and their signals collide, they listen to the network to sense if it is currently in use. If a collision does occur, it will be detected and the sender will wait for an amount of time determined by a backoff algorithm.

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) The access method used in Wireless networks for example. It is similar to CSMA/CD, but CA means that a node broadcasts a warning it is about to use the network, before it actually starts to transmit data.
Token Passing This is the access method used in Token Ring and FDDI networks. A token is passed around the network from station to station, when a station does not need to transmit data it passes the token to the next station in the logical ring. A station that receives the token and needs to transmit data seizes the token and sends a data frame, the receiving station marks the data frame as read and passes it forward along the ring to the source station. During this time no other station can transmit data which rules out collisions. The source station releases the token (passing it to the next station) when it receives the data frame and verified it was read.

NETWORK INTERFACE CARDS (NICs)

A Network Interface Card (NIC), typically an expansion card in a computer, is used to connect to the physical network media. Some mainboards and most portable computers are equipped with a built-in (onboard) NIC. NICs are available for different types of network media, the most common today being Ethernet NICs with a RJ-45 socket for UTP/STP cabling. To install a network interface card you need a free ISA or PCI expansion slot and an appropriate driver that the computer's operating system will use to communicate with the NIC. Some older ISA NICs can be manually configured to use a particular IRQ. This is done by setting jumpers or dip switches. Some other NICs allow the IRQ to be configured through the use of configuration software.

Many of today's NICs are equipped with status indicators in the form of leds. These leds can be used to troubleshoot network problems. Typically one green led indicates the NIC is physically connected to the network and flashes when activity occurs, i.e., the port is transmitting or receiving data, this is also known as a heartbeat. When the NIC supports multiple speeds, for example 10 and 100 Mbps, there can be a green led for each speed, of which one is lit indicating the current speed, possibly auto-negotiated with a hub or switch. Some NICs, as well as other network devices such as hubs, include and orange or red led which flashes when collisions occur. If the collision LED flashes repeatedly or continuously, the NIC maybe be configured incorrectly or may be malfunctioning, or there may be other devices utilizing the network heavily.

As described earlier, networks interfaces are physically configured with an address known as the MAC address (MAC is short for Media Access Layer), layer 2 address, Burned In Address (BIA), or physical address. Here's an example of a MAC address: 00-10-E3-42-A8-BC. The first 6 hexadecimal digits specify the vendor/manufacturer of the NIC, the other 6 define the host. MAC addresses are supposedly unique across the planet.

Half duplex vs. Full-duplex communication
Half-duplex means that only one host can communicate at a given time, two hosts communicating with each other will take turns transmitting. In full-duplex communication both hosts can transmit at the same time, in theory allowing twice as much data to be transmitted over the same connection.
The connections able to run at full-duplex are cross-cable connections and connections to a port on a switch, where collisions cannot occur because each end has it's own wire pair (separate segment).

MEDIA

The list below shows some important considerations to make when choosing the proper media for a particular network solution:
Cost Besides the high cost of some cable types you also have to consider that the equipment that is used to put the signal on the cable, and take it off the cable, differs a lot in price.
Maximum distance Network media is bound to a maximum cable length, because when a signal travels through the cable it will get weaker.

Flexiblity Some types of media are more flexible than others. Typically, the thinner the cable the easier it is to implement. Except for fiber optic cabling, this has to be placed with care to avoid breaks.

Susceptibility to electrical interference Some cables, such as UTP, are more susceptible to nearby high-voltage devices or other sources of electrical interference, than other cables, such as STP or fiber-optics.

Susceptibility to cross-talk Cross-talk refers to interference from other data cables.
Susceptibility to fire. Plenum cabling is designed to better withstand the introduction of fire than PVC, and, if burned, generates less smoke toxicity as a result. It is less flexible and it is more expensive. Plenum is typically used in environments such as hospitals.

RS-232

The RS-232 standard specifies serial cabling using DB-9 or DB-25 connectors. The maximum length for a RS-232 cable is 50 feet (15.25 meters) at a baudrate of 19200. The RS-232 standard is designed to supports data transfer rates up to 20 Kbps.

TWISTED PAIR

The most common type of twisted pair cabling is Unshielded Twisted Pair (UTP) cabling. This type of cabling is typically made up of 4 twisted pairs of copper wires as depicted in the image below. Each wire has its own cover, and so does the complete bundle. UTP cabling is categorized using a number. The required category depends on the network technology and the desired transmission speed. Following are the UTP categories:
Cat.1 Used for voice/telephone communication only.
Cat.2 Data rates up to 4 Mbps.
Cat.3 Data rates up to 4 Mbps in TokenRing networks, 10 Mbps in Ethernet networks, bandwidth of 16 MHz.
Cat.4 Data rates up to 16 Mbps in TokenRing networks, 10 Mbps in Ethernet networks, bandwidth of 20 MHz.
Cat.5 Data rates up to 100 Mbps, bandwidth of 100 MHz
Cat.5e Data rates up to 1 Gbps (Gigabit Ethernet), bandwidth of 100 MHz rated (tested up to 350 Mhz).
Cat.6 Data rates up to 1 Gbps (Gigabit Ethernet), bandwidth of 250 MHz rated (tested up to 550 Mhz).

10BaseT Ethernet, 100BaseTX Fast Ethernet, 1000BaseT and Token Ring are the most common networks that use twisted pair cabling and are described below.

10BaseT
The 10BaseT specification uses Cat 3, 4 and 5 UTP cabling in a star/hierarchical topology. Devices on the network are connected through a central hub.
10BaseT specifications:
- Maximum segment length is 100 meters
- Maximum data transfer speed is 10Mb/s
- Cat 3, 4 and 5 Unshielded Twisted Pair (UTP)

100BaseTX (Fast Ethernet, 802.3u)
Is similar to 10BaseT, except it requires at least Category 5 UTP or Category 1 STP cabling. Only uses 4 of the 8 wires like just like 10BaseT. The maximum data transfer rate is 100 Mb/s.

802.5 (Token Ring)
Token Ring uses the token passing method described earlier in this TechNote. While the logical topology of a Token Ring network is a ring, the physical topology is star/hierarchical as illustrated in the diagram below. Stations connect to MultiStation Access Units (look a bit like hubs) using UTP cabling which in turn are connected in a physical ring.

Token Ring specifications:
- Data transfer rate is 4 or 16 Mb/s
- Uses Twisted Pair cabling (Cat 3 for 4 MB/s, Cat 5 for 16 Mb/s)
- Logical topology ring, physical topology is star

Token Ring is originally created by IBM, and was later standardized by IEEE under the 802.5 specification. The original IBM Token Ring specification uses IBM Class 1 STP cabling with IBM proprietary connectors. This connector is called the IBM-type Data Connector (IDC) or Universal Data Connector (UDC), and is male nor female.

COAXIAL
Coaxial cabling is used primarily in 10Base2 (Thinnet) and 10Base5 (Thicknet) Ethernet networks. Coaxial cable uses a copper core with a protective shield, to reduce interference. The shield is covered with the outside cover made from PVC or plenum. The most common types are listed in the following table.
RG-58U 50 Ohm, used in 10Base2 Ethernet networks (Thinnet).
RG-8 50 Ohm, used in 10Base5 Ethernet networks (Thicknet).
RG-59 / RG-6 75 ohms, used for cable television (hence, cable modem access), video, digital audio, and telecommunication applications (for example for E1 coaxial cabling).
10Base2

10Base2 specifications:
- Maximum segment length is 185 meters
- Maximum data transfer speed is 10Mb/s
- 0.2 inch, 50 ohm RG-58 coaxial cable (Thinnet)

10Base5
Commonly referred to as Thicknet, commonly uses a bus topology. Stations are attached to the cable using MAUs, a transceiver that is attached to the cable using vampire taps that pierce the cable. A cable with AUI connectors is used to connect the transceiver to the network interface on for example a computer, hub or repeater. Both cable ends are terminated using a 50 ohm terminator.
10Base5 specifications:
- Maximum segment length is 500 meters
- Maximum data transfer speed is 10Mb/s
- 0.4 inch, 50 ohm coaxial RG-8 cabling (Thicknet)

FIBER OPTIC
Fiber optic cabling is a rather new technology that allows for fast data transfer over large distances. Fiber optic cabling is not susceptible to electrical interference, but needs expensive equipment and is fragile. There are two main types of fiber optics, the first is multi-mode, which is typically used in corporate networks' backbone. In a multi-mode cable, light travels down the fiber cable in multiple paths. Essentially, the light beam is reflected off the cladding (material surrounding the actual fiber) as it travels down the core. The other type is single-mode, this type is typically used by telephone companies to cover very large distances. In a single-mode cable, light travels thru the cable without interacting with the glass cladding (material surrounding the actual fiber), maintaining signal quality for great distances.

Fiber optic cabling is connected using SC, ST or MIC connectors.
Network technologies that use fiber optic cabling include 100BasesFX and FDDI.

100BaseFX (802.3u)
Similar to 100BaseTX but designed to operate over 2 strands of single-mode or multi-mode fiber cabling. One cable is used to send the other is used for collision detection and receiving. The maximum length of a 100BaseFX link is 400 meters in half-duplex mode, 2000 meters in full-duplex mode.

- 1000BaseLX, uses multi-mode fiber with a maximum length of 550 meters or single-mode fiber with a maximum length of 5 km
- 1000BaseSX, uses multi-mode fiber with a maximum length of 500 meters

FDDI

Another token-passing network technology is Fiber Distributed Data Interface. FDDI networks are often used as backbones for wide-area networks providing data transfer rates up to 100 Mb/s using fiber media. The use of fiber makes it immune to electrical interference, and allows it to transmit data over greater distances. FDDI provides fault tolerance by using a dual counter-rotating ring configuration, an active primary ring and a secondary ring used for backup.

WIRELESS

Infrared
Infrared (IR) communication is typically used between devices such as PDAs, laptops and printers. An advantage of IR communication is that it is not susceptible to electrical interference. The main disadvantage, besides the rather short maximum supported distance between devices, is that there must be a clear path between the devices. Supports data transfer rates up to 4 Mbps.

802.11b (Wi-fi)

The 802.11b standard specifies wireless Ethernet LAN technology. The topology used in wireless networks is known as cellular. It is a wireless structure where stations send signals to each other via wireless media hubs. The access method for 802.11b is CSMA/CA. Clients connect via wireless access points with data transfer rates up to 11 Mbps. 802.11b operates in the 2.4 GHz range. Another WLAN standard that has recently emerged, 802.11a, offers a maximum transmission speed of 54 Mbps at 5 GHz frequency.

NETWORK COMPONENTS

Repeaters Used to extend the maximum distance a cable segment can span. Repeaters grab the incoming electrical signal from the cable, amplify it, and send it out.
Hubs Hubs, also known as concentrators or multiport repeaters, are used in star/hierarchical networks to connect multiple stations/cable segments. There are two main types of hubs: passive and active. An active hub takes the incoming frames, amplifies the signal, and forwards it to all other ports, a passive hub simply splits the signal and forwards it.
Bridges Used to increase network performance by segmenting networks in separate collision domains, or increase the network size. Bridges are not aware of upper-layer protocols such as TCP/IP or IPX/SPX. They keep a table with MAC addresses of all nodes, and on which segment they are located.

Switches Similar to bridges; they also keep a table with MAC addresses per port to make switching decisions. The main difference is that a switch has more ports than a bridge, and instead of interconnecting networks it is typically used to connect hosts and servers like a hub does, but offers dedicated bandwidth per port, hence offers much higher network performance than hubs.

Routers Routers are used to interconnect multiple (sub-)networks and route information between these networks by choosing an optimal path ("route") to the destination based on addressing information from protocols such as TCP/IP or IPX/SPX. Router are also typically used to connect a LAN to a WAN or another LAN, which can use different technologies such as Token Ring, Ethernet, ISDN, Frame Relay etc.

Gateways Used to connect networks with dissimilar technologies, for example a Microsoft TCP/IP network and NetWare IPX/SPX network can be connected using a gateway. Typically implemented in software on a router.
Firewalls Protects a private network from external users, typically those from the Internet, by hiding the internal network and filtering incoming packets. A firewall is not always a hardware device, it can be implemented in software on a router or proxy server as well.

PROTOCOLS

TCP/IP

TCP/IP is today's most popular network protocol and is the protocol in the Internet. It is a routable protocol that provides connection between heterogeneous systems, these are the main reasons the protocol is so widely adapted; for example it allows communication between UNIX, Windows, Netware and Mac OS computers spread over multiple interconnected networks. The "TCP/IP protocol" is actually the "TCP/IP suite" composed of many different protocols each with its own functions. The two main protocols are in its name: the Internet Protocol and the Transmission Control Protocol.

IP addressing is assigning a 32-bit logical numeric address to a network device. Every IP address on the network must be unique. An IP address is represented in a dotted decimal format, for example: 159.101.6.8. As you can see the address is divided in 4 parts, these parts are called octets. The current used addressing schema in version 4 of IP is divided in 5 Classes:
Classes First Octet
Class A 1 126
Class B 128 191
Class C 192 223
Class D 224 239
Class E 240 254

A subnet mask is used to determine which part is the network part and which is the host part.
Default subnet masks:
Class A 255.0.0.0
Class B 255.255.0.0
Class C 255.255.255.0

IANA reserved 4 address ranges to be used in private networks, these addresses won't appear on the Internet avoiding IP address conflicts:
- 10.0.0.0 through 10.255.255.255
- 172.16.0.0 through 172.31.255.255
- 192.168.0.0 through 192.168.255.255
- 169.254.0.1 through 169.254.255.254 (reserved for Automatic Private IP Addressing)

IPX/SPX
Although current versions of Novell Netware use TCP/IP, before Netware version 5, IPX was the protocol in Netware networks. It is a small and easy to implement routable protocol developed by Novell and based on the Xerox Network System. The Netware protocol suite is a suite of several protocols for different functions, the most important being IPX and SPX. IPX is similar to the Internet Protocol from the TCP/IP suite, it is a connectionless Layer 3 (Network layer) protocol used to transfer datagrams between hosts and networks. SPX is the Transport protocol used to provide reliable transport for IPX datagrams, similar as TCP does for IP.



The frame types of two Netware hosts must match to enable communication without a router. IPX can use several frame formats, of which the two most important are listed in the following table.
Frame Format Frame Type Netware Versions
Novell 802.3 raw 802.3 Default frame type for Netware 3.11 and earlier. Supports only IPX/SPX as the upper layer protocol
IEEE 802.3 802.2 Default frame type for Netware 3.12 and 4.x. The main difference with Novell's 802.3 format is the addition of LLC field, which specifies the upper-layer protocol, such as IPX or IP.

An complete IPX network address is 80 bits in length and is represented in a hexadecimal format. As with all routable protocols it needs a network and a host portion, the network portion is 32 bits in length and is manually configured. The host portion is 48 bits in length and is derived from the MAC address of the host's network interface.

Examples of complete IPX internetwork addresses are:
- 0CC001D8.0050.BF61.6C71
- 0000ABBA.0060.9736.954B
- 00000046.0060.E92A.C2A4

NWLINK is Microsoft's implementation of IPX/SPX which allows Windows clients to communicate with Netware servers.

AppleTalk
AppleTalk was developed by Apple Computers in the early 1980s to allow file and printer sharing and mail functionality between Macintosh computers. A Mac that shares resources is called a server, and the computer connecting to it a client. Like TCP/IP, AppleTalk is not just one protocol, but a suite of several protocols for different functions. It is built-in in every Macintosh computer and requires virtually no user interaction, therefore it is very easy to administer in small network environments. Address assignment in AppleTalk networks is automatically. Besides Ethernet and TokenRing, AppleTalk can also be used on Apple's own network technology called LocalTalk, which uses UTP/STP cabling.

NetBEUI/NETBIOS

NETBios Extended User Interface is a non-routable Transport layer protocol. The reason it is non-routable is in its flat addressing schema, NETBEUI uses Netbios names to identify computers on the network that do not contain a network portion. Netbios names are sometimes referred to as friendly names. NetBIOS names are 16 characters in length and cannot contain any of the the following characters: \ / : * ? " < > | The first 15 characters represents a unique name identifying a resource, the 16th character (if you would set a name of 8 characters it is padded with spaces up to 15 characters long to allow a '16th' character) is a suffix identifying the type of resource or group of resources. For example the redirector, server, or messenger services can be installed on one computer resulting in three times the same name but with different suffixes.

NETBEUI is a broadcast protocol, meaning a computer running NETBEUI discovers the MAC address from the intended communication partner by sending out a broadcast with the NETBIOS name. The main advantage of NETBEUI is that it is small in size and easy-configurable.