Sunday, 13 May 2012

CH 1 LIVING IN A CENTRIC WORLD





Living in a Network-Centric World

Objectives
Upon completion of this chapter, you will be able to
answer the following questions:
How do networks impact our daily lives?
What is the role of data networking in the
human network?
What are the key components of a data network?
What are the opportunities and challenges posed
by converged networks?
What are the characteristics of network
architectures?

Communicating in a Network-Centric World
Humans are social animals who depend on the contact with others for daily needs.
Throughout human being times past, people, with few exceptions, have depended on the structure of various community networks for safety, food, and companionship. People have been networking for a very long time.
The ways in which human interact are constantly changing. As technical developments
all the way through history have come about, the methods of human communication have developers well. At one time, sounds and gestures were all humans used to communicate, but now the Internet allows people to instantaneously share all types of statement—documents,
pictures, sound, and video—with thousands of people near and far away using computers.
Networks Supporting the Way We Live
Just a few years ago, people communicated mostly on a local level because communicating with people far away was complicated and expensive. People talk in person or used the telephone for most quality communication, the postal service delivered most of the written messages, and the television broadcast one-way video communication. Each of these methods is still working, but each and every one three of them are converging into web-based communication technologies. The extended reach and the reduced cost of communication through the Internet has changed the way businesses interact with their customers, the way people share information and resources, and the way friends and families stay close to each other.

As with every advance in communication technology, the creation and interconnection of robust data networks are having a profound effect. Early data networks were limited to exchanging character-based information between connected computer systems. Current networks have evolved to carry voice, video streams, text, and graphics between many different types of devices. Previously separate and distinct communication forms have converged onto a common platform. This platform provides access to a wide range of alternative and new communication methods that enable people to interact directly with each other almost instantaneously.

 
The use of the Internet spread quickly as connectivity became available in the 1990s. The early users of the World Wide Web were mostly university researchers exchanging information, but other people and businesses quickly figured out how to take advantage of webbased communications. This sparked the creation of many new businesses and careers.
The immediate nature of communications over the Internet encourages the formation of global communities. These communities foster social interaction that is independent of location or time zone. Technology is perhaps the most significant change agent in the world today, as it helps to create a world in which national borders, geographic distances, and physical limitations become less relevant and present ever-diminishing obstacles. The creation of online communities for the exchange of ideas and information has the potential to increase productivity opportunities across the globe. As the Internet connects people and promotes unfettered communication, it presents the platform on which to run businesses, to address emergencies, to inform individuals, and to support education, science, and government.
The Internet has quickly become an integral part of our daily routines. The complex interconnection of electronic devices and media that comprises the network is transparent to the
millions of users who make it a valued and personal part of their lives.
Data networks that were once the transport of information from business to business are now also used to improve the quality of life for people everywhere. In the course of a day, resources available through the Internet can help you do the following:
Decide what to wear using online current weather conditions
Find the least-congested route to your destination, displaying weather and traffic video from webcams.
Check your bank balance and pay bills electronically.
Receive and send e-mail at an Internet cafe over lunch.

Obtain health information and nutritional advice from experts all over the world, and post to a forum to share related health or treatment information.
Download new recipes and cooking techniques to create a spectacular dinner.
Post and share your photographs, home videos, and experiences with friends or with the world.
Use Internet phone services.
Shop and sell at online auctions.
Use instant messaging and chat for both business and personal use.






Examples of Today’s Popular Communication Tools
As in the past with novel technologies like the telephone and television, the general public readily adapted the Internet into daily use. The existence and broad adoption of the Internet has ushered in new forms of communication that empower individuals to create information that can be accessed by a global audience. Popular communication tools include instant  messaging, blogs, podcasts, and wikis. 
Instant messaging (IM) is not a new technology, but recent enhancements have increased its user base. IM is real-time text communication between two or more users. Based on the earlier service known as Internet Relay Chat (IRC), it has expanded to include voice, photo and video sharing, and file transfers. IM is different from e-mail in that e-mail can be delayed when sent, but IM is, as its name implies, instantaneous. IM is an increasingly popular tool used by customer service centers to assist customers and friends in communicating with each other.
The first generation of web use was as a place for people to find static information, educational resources, and business information. But web content is changing from a place for people to get information to a place for people to contribute information as well. The users of the web are, in many ways, becoming the creators of the content. The emergence and use of social software tools such as blogs, podcasts, and wikis enable the interaction and contribution of users.
Blogs, also known as weblogs, are web pages where people can publish their personal opinions and thoughts about any conceivable topic. Blogs, for better or worse, allow unfiltered and unedited publication of ideas from experts and non experts alike. This is important because it demonstrates a shift from reliance on traditional media content from experts to a reliance on other users to provide their personal knowledge.

poodcasting is an audio-based medium that originally enabled people to record audio and convert it for use with iPods—small, portable devices for audio playback manufactured by Apple. The ability to record audio and save it to a computer file is not new. However,  podcasting allows people to deliver their recordings to a wide audience. The audio file is placed on a website (or blog or wiki), where others can download it and play the recording on their computers, laptops, and iPods.
Wikis are another example of publicly created web content. Individuals create blogs, but wiki web pages are created and edited by groups of people sharing information. The best known example of a wiki is the Wikipedia, an online encyclopedia made up of public contributions edited by public users. Thousands of people contribute their specialized knowledge to the Wikipedia, and anyone can access the information at no cost. Many groups create their own wikis for member instruction, and many organizations create limited wikis as an internal collaboration tool. A collaboration tool is web-based software that allows people  to work together on a project over the web.


Networks Supporting the Way We Learn
The advances in the Internet and collaboration tools have been the force behind major changes in education. As web reliability and access have increased, more institutions have come to depend on technology to perform core educational functions. For example, distance education was once limited to correspondence, videos, or video and audio conferences. With newer collaboration tools and stronger web technologies, online learning can engage remote students in interactive learning and real-time assessment. The classes can use document sharing, wikis, online video, and online testing software to enhance learning opportunities. Student learning is becoming less dependent on location and schedule, which opens courses to potential students who previously could not attend classes. The methods of both face-to-face and online instruction are changing with the introduction of web tools such as wikis. Traditionally, a teacher provided course content and the class might have benefited from some discussions. With online tools equally available to all students, many classes focus on sharing the opinions and expertise of students. This is a significant change for many students and instructors, but it is an example of the impact of technical change on society’s traditions.
The administration side of instruction has also changed. You might have enrolled in this course on the web and paid with an online bank account. Your final grades might be posted on a school website, and you might never have a face-to-face meeting with your advisor. This is the business side of education, and it is changing as new management tools become avaliable.

The structure of this course is an example of the influence that the changes of the web have had on instruction. The Cisco Networking Academy Program, which offers this course, is an example of a global online learning experience. The instructor provides a syllabus and establishes a preliminary schedule for completing the course content. The Academy program supplements the expertise of the instructor with an interactive curriculum that provides many forms of learning experiences. The program provides text, graphics, animations, and a simulated networking environment tool called Packet Tracer. Packet Tracer provides a way to build virtual representations of networks and emulate many of the functions of networking device.

Students can communicate with the instructor and fellow students using online tools like e-mail, bulletin/discussion boards, chat rooms, and instant messaging. Links provide access to learning resources outside the courseware. Blended e-learning provides the benefits of computer-based training while retaining the advantages of an instructor-led curriculum Students have the opportunity to work online at their own pace and skill level while still having access to an instructor and other live resources. In addition to the benefits for the student, networks have improved the management and administration of courses as well. Some of these online functions include enrollment, assessment delivery.


Current and accurate training materials

Collaboration among vendors, equipmentmanufacturers, and training providers ensures that the course ware is up to date with thelatest processes and procedures. When errors in materials are found and correct, the new courseware is immediately on hand to all employees.
Availability of training to a wide audience:

Online training is not dependent on travel schedules, instructor availability, or physical class size. Employees can be given deadlines by which training is to be completed, and they can access the course ware when it  is fitting.
Consistent quality of instruction:  

The quality of the instruction does not vary as it would if different instructors were delivering an in-person course. The online curriculum provides a consistent core of instruction to which instructors can add additional expertise.

Cost reduction:
In addition to reducing the cost of travel and the lost time associated with travel, there are other cost-reducing factors for business related to online training. It is usually less expensive to revise and update online course ware than it is to revise paper-based materials. Facilities to support in-person training can also be reduced or eliminated.


Communication: An Essential Part of Our Lives
Communication in our daily lives takes many forms and occur in lots of environments. We have different potential depending on whether we are chatting through the Internet or participating in a job interview. Each situation has its parallel expected behaviors and styles. These outlook are the rules of communication, and some of the elements are universal. Taking a faster look at the way humans communicate will introduce lots of of the necessary elements of network communication as well.

What Is Communication?
People have many behavior of communicating with each other. Whether the communication is verbal or nonverbal, face-to-face or over the telephone, before in handwritten letter or in a chat room, successful communication requires common rules.

The rules of communication are also known as protocols. Some of the protocols required for communication to occur include the presence of
An identified sender and receiver
An agreed-upon method of communicating (face-to-face, telephone, letter, photograph, and so on)
Common language and grammar
An agreed-upon speed and timing of delivery (for example, “Please slow down so that I can understand you.”)
Confirmation or recognition requirements (for example, “Is that clear?” “Yes, thank you.”)
Not all communications have the same agreed-upon protocols. For example, an important legal letter can require a signature and response from the recipient, except personal letters need no such appreciation.People are oblivious of many of the rules they follow while communicating because The rules of communication are also known as protocols. Some of the protocols required for communication to occur include the presence of
An identified sender and receiver
An agreed-upon method of communicating (face-to-face, telephone, letter, photograph, and so on)
Common language and grammar
An agreed-upon speed and timing of delivery (for example, “Please slow down so that I can understand you.”)

Confirmation or recognition requirements (for example, “Is that clear?” “Yes, thank you.”)
Not all communications have the same agreed-upon protocols. For example, an important legal letter can require a signature and response from the recipient, except personal letters need no such appreciation.

Quality of Communication

Computers and computer networks have no such inbuilt communication knowledge, but like protocol are still required for network devices to communicate. Successful communication linking computer network devices, just as is true with communication between people, occurs when the meaning of the message understood by the recipient matches the meaning intended by the sender.
There are many prospective barriers to successful communication between computers on a network. The process of sending a message on a computer network can be multipart and have many steps and conditions, and any step poorly performed or condition not suitably met can potentially ruin the message. The steps and conditions, or factor, can be separated into internal along with external groups. The external factors stem from the complexity of the network and the number of device handling the message en route to the destination. Examples of external factors include the  following .
The quality of the pathway between the sender and the recipient.
 The number of times the message has to change form The number of times the message has to be redirected or readdressed .
■ The number of other messages being transmitted simultaneously on the communication network.
■ The amount of time allotted for successful communicatio Internal factors include the following:
■ The size of the message
■ The complexity of the message
■ The importance of the message
More complex messages can be more difficult for the recipient to understand, and larger messages have a greater potential to be distorted or incomplete at the destination.

 
The Network as a stage

The ability to reliably communicate to anyone, anyplace, is becoming gradually more important to our private and business lives. Adding to the demand of immediacy is the requirement that different types of messages, such as phone, text, and video, be accommodated as normal forms of communication. To support the immediate delivery of the millions of various messages being exchanged among people all over the world, we rely on a web of interconnected networks. The following sections explain communication over networks, different basics that make up a network, and convergence.

Communicating over Networks
Networks directly impact how we live, and the role of networks is increasingly important to people in all parts of the world. The task of constantly delivering millions of messages all together would be too much for any one network to perform. Therefore, a web of smaller, interconnected networks of various sizes and capabilities delivers the many letters and data streams around the world.

 
Elements of a Network
The webs of data or information networks vary in size and capabilities, but all networks have four basic elements in common:
Rules or agreements: Rules or agreements (protocols) govern how the messages are sent, directed, received, and interpreted.
Messages: The messages or unit of in order travel from one device to another.
Medium: A medium is a means of interconnecting these devices, that is, a medium can transport the messages from one device to another.
■ Devices: Devices on the network exchange messages with each other.




Early networks had anecdotal standards and, as a result, could not communicate easily with each other. Now global standardization of these basics enables easy communication between networks regardless of the equipment company.
People use many technologies and devices that they do not completely understand. Driving a car, for example, is a general function for many people. When a driver starts a car, put it into gear, and steps on the chat many systems begin to work together. The car moves because an ignition system started the car, a fuel system regulates power, electrical systems run lights and gauges, and a complex transmission chooses appropriate gears to make thecar move as directed by the driver. All of this happens under the hood and out of sight and mind to the driver, who focuses on the task of driving safely to a destination. Most drivers know small or nothing about how a car works but are still able to use it well for their own purpose.
Computer networks are similar to cars in the example. Two people communicating on end devices in different networks can do so only if many complex processes are successfully completed. These processes contain a message, some form of media, various devices, and protocols working together.

Message
Messages is a basic term that encompasses web pages, e-mail, instant messages, telephone calls, and other form of communication enabled by the Internet. The message must be one that the network can carry. First, the messages must be supported in software at the end devices. Instant messaging and chat, for example, require some software setup before asession can begin. Different software is required for audio and video conferencing. Thesesoftware programs that support communication functions are called services,  and to initiate a message, a service must be installed. Examples of services include e-mail, IP telephony, and use of the World Wide Web.
It does not matter whether the message is text, voice, or video, because all forms are convertedinto bits, binary-coded digital signals, to be carried over a wireless, copper, or fiberoptic connection. The digital signal can change with the media, but the original message content will remain intact.
Medium
The medium that physically carries the message can change several times between the sender and the receiver. Network connections can be wired or wireless.
In wired connections, the medium is either copper, which carries electrical signals, or optical fiber, which carries light signals. The copper medium includes cables, such as twistedpair telephone wire, coaxial cable, or most commonly, what is known as Category 5 unshielded twisted-pair (UTP) cable. Optical fibers, thin strands of glass or plastic that carry light signals, are another form of networking media. In wireless connections, the medium is the Earth’s atmosphere, or space, and the signals are microwaves. Wireless media can include the home wireless connection between a wireless router and a computer with a wireless network card, the terrestrial wireless connection between two ground stations, or the communication between devices on Earth and satellites. In a typical journey across the Internet, a message can travel across a variety of media.




RULES
All communication processes happen, as far since humans can tell, in an instant, and tens of thousands of processes can happen in a single second. To work properly, the network process must be strongly controlled. Rules govern every step of the process, from the way cables are designed to the way the digital signals are sent. These rules are called protocols, and the communications industry has standardized most of them to allow people in different places with different equipment to communicate. The most common protocols are IP (Internet Protocol) and TCP (Transmission Control Protocol). These protocols work together and are usually known as the TCP/IP protocol stack. TCP/IP works along other protocols, for example, Extensible Messaging and Presence Protocol (XMPP), which is an instant messaging protocol, to provide communication rules involving different services.
 lists some common services and the protocols that support them.



Service Protocol (“Rule”)
World Wide Web (WWW)      HTTP (Hypertext Transport Protocol)


E-mail                                    SMTP (Simple Mail Transport Protocol)
                                                       POP (Post Office Protocol)
                                               
 Instant message                   XMPP (Extensible Messaging and
                                                     Presence Protocol)
                       
(Jabber, AIM)                          OSCAR (Open System for Communication
                                                     in  Realtime)

IP telephony                        SIP (Session Initiation Protocol)

People frequently only picture networks in the abstract sense: We create and send a text message, and it almost straight away shows up on the destination device. Although we know that stuck between our sending device and the receiving device there is a network over which our communication travels, we rarely think about all the parts and pieces that make up that infrastructure.

The following list together how the basics of networks—devices, media, and services—are connected by rules to deliver a message:
1. An end user types an direct message to a friend using an application on a PC.
2. The instant message gets converted into a format that can be transmitted on the network.
All types of message formats—text, video, voice, or data—must be converted to bits before being sent to their destinations. After the instant message is converted to bits, it is ready to be sent on the network for deliverance.   
  
 The network interface card (NIC) in the PC generates electrical signals to represent the bits and places the bits on the medium so that they can travel to the first network device.
4. The bits are passed from device to device in the local network.
5. If the bits need to leave the local network, they leave through a router connecting to a different network. There can be dozens, even hundreds, of plans handling the bits as they are routed to their destination.
6. As the bits get close to their target, they once again get passed from end to end local devices.
7. Finally, the NIC on the destination device accepts the bits and converts them back into a readable text message.

Converged Networks
Communication technologies evolved at diverse times and in different places in the twentieth century. Many developments in radio broadcast knowledge were driven by military necessity, yet developments in broadcast television grew to answer a market demand. The telephone evolved as a energetic technology and then as a wireless technology. Computer communication
developments came a good deal later in the century. For example, the first text e mail message be sent in the 1960s, but e-mail did not become popular until the 1980s. Now it is quite common to use a computer for instant messaging, telephone calls, and video sharing. The technology and protocols of each of these communication methods urban largely independent of each other, and most users of TV, telephone, and computer services pay different providers for each service. But recent developments in each area have driven broadcast and telephony to the digital technology already used by computers. This coming together of technologies onto a digital platform is called convergence.
Convergence occurs while telephones, broadcasts, and computer communications all use the same rules, devices, and media to carry their messages. On a converged network, or platform, different devices, such as televisions or cell phones, will use a common network  infrastructure to communicate.


                            CONVERGE NETWORK
 
Providing Network Security
The Internet has proven to be fertile ground for business, and business-to-business transactionsand e-commerce are sustaining significant growth every year. The same environment that attracts legitimate business, however, also attracts scam artists and vandals. Compromising the integrity of company assets could have serious business and financial repercussions. As a result, network security is a major concern of web providers and users, and web safety is a key part of any network management plan.
A network security breach can lead to a variety of serious consequences, including the following:
Network outage, causing a loss of communication and business transactions
Loss of personal or business funds
Theft of intellectual property such as project bids, patents, and strategic plans
Exposure of confidential customer data
Each of these examples could cause a customer to lose confidence in the company and hasten a move to a more reliable vendor. To provide security, a network manager must address two areas:
Network infrastructure security
Content security
Securing the network infrastructure means protecting the devices from outside contact.
Locking computer room doors and using quality password protection on network equipment and software are simple steps that can go a long way to securing an infrastructure. Securing network content means protection of data stored on network devices and the protection of packets carrying data into or out of the network. Content security on a network means ensuring confidentiality, maintaining communication integrity, and ensuring network
availability.
Ensuring Confidentiality
Data privacy is maintained by allowing only the intended and authorized recipients— individuals, processes, or devices—to read the data. Different methods ensure data confidentiality. Having a strong system for user authentication, enforcing passwords that are difficult to guess, and requiring users to change passwords frequently help restrict access to communications and to data stored on network-attached devices. Where appropriate,
encrypting content ensures confidentiality and minimizes unauthorized disclosure or theft of information.

Trends in Networking
Making precise predictions about the distant future of technology is a difficult task. Looking at current trends can show near-term developments that are on the horizon and the career opportunities that can be available to you.
Where Is It All Going?
The convergence of the many different communication media onto a single network platform is fueling exponential growth in network capabilities. Three major trends are contributing to the future shape of complex information networks:
Increasing number of mobile users
Proliferation of network-capable devices
Expanding range of services
The following sections describe each trend and its possible impact.

Mobile Users
The trend of mobile use is contributing to changes in the traditional workplace from one where workers travel to a central office to one where the office travels with the worker.
More mobile workers can use handheld devices such as cell phones, laptops, and personal digital assistants (PDA), which have evolved from luxury gadgets to necessary tools.
Increased wireless service in metropolitan areas has unleashed people from their wired computers and freed them to work away from their desks.
Mobile workers and those who rely on handheld devices require more mobile connectivity to data networks. This demand has created a market for wireless services that have greater flexibility, coverage, and security.

New and More Capable Devices
The computer is only one of many devices on today’s information networks. A proliferation of new technologies takes advantage of available network services. Homes and small offices have access to services such as wireless technology and increased bandwidth that were once available only to corporate offices and educational institutions. Web-enabled phones give users access to Internet applications and e-mail anywhere in cell phone range.
The functions performed by cell phones, PDAs, organizers, and pagers are converging into single handheld devices with continuous connectivity to providers of services and content. These devices, once thought of as “toys” or luxury items, are now an integral part of how people communicate. In addition to mobile devices, we have VoIP devices, gaming systems, and a large assortment of household and business gadgets that can connect and use network services.
Increased Availability of Services
The widespread acceptance of technology and the fast pace of innovation in networkdelivered services create a spiraling dependence. To meet user demands, new services are introduced and older services are enhanced. As the users come to trust these expanded services, they want even more capabilities. The network then grows to support the increasing demand. People depend on the services provided over the network, and therefore depend on the availability and reliability of the underlying network infrastructure. These highly mobile users and their increasingly capable devices require more complex services that are reliable and secure. As these improved tools and services become available to the public, the public demand for network bandwidth will increase as well. These increases in demand point to growing networks and the new opportunities that will come with them. The challenge of keeping pace with an ever-expanding network of users and services is the responsibility of trained network and IT professionals.
Networking Career Opportunities
The implementation of new technologies is constantly changing the fields of information technology (IT). Network architects, information security managers, and e-commerce specialists are joining software engineers and database administrators in the IT workplace.
As non-IT fields, such as hospital management and education, become more technical in nature, the need for IT professionals with backgrounds in diverse fields such as medicine and education will increase.

Summary
Data networks play an increasing role in the way humans communicate with each other. The Internet and local networks directly impact the way people live, learn, and work. The process for delivering messages across a computer network involves protocols defining agreements on how to deliver the message between user devices across a medium. The type of media and the devices used to deliver the message are subject to appropriate protocols as well.

Converged data networks can provide different types of services, including text, voice, and video messages between end users. Converged networks provide businesses with an opportunity to reduce costs and offer users a variety of services and content. However, the design and management of converged networks require extensive networking knowledge and skills
if all services are to be delivered as expected to users.
A network’s architecture must provide scalability, fault tolerance, quality of service, and security. QoS is an important part of network planning that can affect user productivity. Prioritization of network data can allow an efficient balance of data types flowing through the network. Security of network infrastructure and content will continue to be an essential element of a successful network, as it directly affects user confidence.

1. Which form of communication is a real-time, text-based communication type used between two or more people who use mostly text to communicate?
A. Weblogs
B. Wikis
C. Instant messaging
D. Podcasting


2. Which type of network provides customers with limited access to corporate data such as inventory, parts lists, and orders?
A. Intranet
B. Extranet
C. Internetwork
D. Internet


3. _______________ are collaborative web pages created and edited by users.
Packet Tracer Companion.

 
4. What prioritizes traffic and its characteristics to manage data?
A. Network administration
B. Network traffic
C. QoS strategy
D. Network evaluation


5. Rules that govern the process of network communication are called ______________.
6. What network traffic processes must be in place for quality of service strategies to work correctly? (Choose two.)
A. Traffic is classified based on quality of service requirements.
B. Priorities are assigned to each classification of application data.
C. Web traffic is always assigned to a high-priority queue for processing.
D. Digital movies are always assigned to the high-priority queue for processing.
E. E-mail traffic is always assigned to the low-priority queue.


7. Copper cables and fiber-optic cables are two types of network ___________________.


8. What are two components of network architecture? (Choose two.)
A. People that comprise the human network
B. Built-in growth potential
C. Data transfer across the network
D. Redundant technologies
E. Corporations that operate and maintain the data network


9. Symbols that graphically represent network devices and media are called __

No comments:

Post a Comment