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Introduction to Networks: Exploring the Network

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Jan 14, 2014.

Chapter Description

This chapter explores the purpose, function, technology, and implications of modern networking technology in home and enterprise environments.

Globally Connected (1.1)

Networks are all around us. They provide us with a way to communicate and share information and resources with individuals in the same location or around the world. This requires an extensive array of technologies and procedures that can readily adapt to varying conditions and requirements.

Networking Today (1.1.1)

For most individuals, the use of networks has become a daily occurrence. The availability of these networks has altered the way in which we interact with each other.

Networks in Our Daily Lives (

Among all the essentials for human existence, the need to interact with others ranks just below our need to sustain life. Communication is almost as important to us as our reliance on air, water, food, and shelter.

The methods that we use to communicate are constantly changing and evolving. Whereas we were once limited to face-to-face interactions, breakthroughs in technology have significantly extended the reach of our communications. From cave paintings to the printing press to radio and television, each new development has improved and enhanced our ability to connect and communicate with others.

The creation and interconnection of robust data networks has had a profound effect on communication, and has become the new platform on which modern communications occur.

In today’s world, through the use of networks, we are connected like never before. People with ideas can communicate instantly with others to make those ideas a reality. News events and discoveries are known worldwide in seconds. Individuals can even connect and play games with friends separated by oceans and continents.

Networks connect people and promote unregulated communication. Everyone can connect, share, and make a difference.

Technology Then and Now (

Imagine a world without the Internet. No more Google, YouTube, instant messaging, Facebook, Wikipedia, online gaming, Netflix, iTunes, and easy access to current information. No more price-comparison websites, avoiding lines by shopping online, or quickly looking up phone numbers and map directions to various locations at the click of a mouse. How different would our lives be without all of this? That was the world we lived in just 15 to 20 years ago. But over the years, data networks have slowly expanded and been repurposed to improve the quality of life for people everywhere.

In the course of a day, resources that are available through the Internet can help you

  • Post and share your photographs, home videos, and experiences with friends or with the world
  • Access and submit school work
  • Communicate with friends, family, and peers using email, instant messaging, or Internet phone calls
  • Watch videos, movies, or television episodes on demand
  • Play online games with friends
  • 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

Innovators are figuring out ways to use the Internet more every day. As developers push the limits of what is possible, the capabilities of the Internet and the role the Internet plays in our lives will expand broader and broader. Consider the changes that have happened over the last 25 years, as depicted in the Figure 1-1. Now consider what changes will happen within the next 25 years. This future holds the Internet of Everything (IoE).

Figure 1-1

Figure 1-1 Evolution of the Network

The IoE is bringing together people, process, data, and things to make networked connections more relevant and valuable. It is turning information into actions that create new capabilities, richer experiences, and unprecedented economic opportunity for individuals, businesses, and countries.

What else do you think we will be able to do using the network as the platform?

The Global Community (

Advancements in networking technologies are perhaps the most significant change agents in the world today. They are helping to create a world in which national borders, geographic distances, and physical limitations become less relevant, and present ever-diminishing obstacles.

The Internet has changed the manner in which social, commercial, political, and personal interactions occur. The immediate nature of communications over the Internet encourages the creation of global communities. Global communities allow social interaction that is independent of location or time zone. The creation of online communities for the exchange of ideas and information has the potential to increase productivity opportunities across the globe.

Cisco refers to this as the human network. The human network centers on the impact of the Internet and networks on people and businesses.

How has the human network affected you?

Networks Support the Way We Learn (

Networks and the Internet have changed everything we do, from the way we learn, to the way we communicate, to how we work, and even how we play.

Changing the Way We Learn

Communication, collaboration, and engagement are fundamental building blocks of education. Institutions are continually striving to enhance these processes to maximize the dissemination of knowledge. Traditional learning methods provide primarily two sources of expertise from which the student can obtain information: the textbook and the instructor. These two sources are limited, both in the format and the timing of the presentation.

Networks have changed the way we learn. Robust and reliable networks support and enrich student learning experiences. They deliver learning material in a wide range of formats including interactive activities, assessments, and feedback. As shown in Figure 1-2, networks now

  • Support the creation of virtual classrooms
  • Provide on-demand video
  • Enable collaborative learning spaces
  • Enable mobile learning
Figure 1-2

Figure 1-2 Networks Support the Way We Learn

Access to high-quality instruction is no longer restricted to students living in proximity to where that instruction is being delivered. Online distance learning has removed geographic barriers and improved student opportunity. Online (e-learning) courses can now be delivered over a network. These courses can contain data (text, links), voice, and video available to the students at any time from any place. Online discussion groups and message boards enable a student to collaborate with the instructor, with other students in the class, or even with students across the world. Blended courses can combine instructor-led classes with online courseware to provide the best of both delivery methods.

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 student enrollment, assessment delivery, and progress tracking.

Networks Support the Way We Communicate (

Networks eliminate geographic and time-zone boundaries, allowing us to easily communicate with individuals from around the world.

Changing the Way We Communicate

The globalization of the Internet has ushered in new forms of communication that empower individuals to create information that can be accessed by a global audience.

Some forms of communication include

  • Instant messaging (IM)/texting: IM and texting both enable instant real-time communication between two or more people. Many IM and texting applications incorporate features such as file transfer. IM applications can offer additional features such as voice and video communication.
  • Social media: Social media consists of interactive websites where people and communities create and share user-generated content with friends, family, peers, and the world.
  • Collaboration tools: Collaboration tools give people the opportunity to work together on shared documents. Without the constraints of location or time zone, individuals connected to a shared system can speak to each other, often across real-time interactive video. Across the network they can share text and graphics, and edit documents together. With collaboration tools always available, organizations can move quickly to share information and pursue goals. The broad distribution of data networks means that people in remote locations can contribute on an equal basis with people at the heart of large population centers.
  • Weblogs (blogs): Weblogs are web pages that are easy to update and edit. Unlike commercial websites, which are created by professional communications experts, blogs give anyone a means to communicate their thoughts to a global audience without technical knowledge of web design. There are blogs on nearly every topic one can think of, and communities of people often form around popular blog authors.
  • Wikis: Wikis are web pages that groups of people can edit and view together. Whereas a blog is more of an individual, personal journal, a wiki is a group creation. As such, it can be subject to more extensive review and editing. Like blogs, wikis can be created in stages, and by anyone, without the sponsorship of a major commercial enterprise. Wikipedia has become a comprehensive resource—an online encyclopedia—of publicly contributed topics. Private organizations and individuals can also build their own wikis to capture collected knowledge on a particular subject. Many businesses use wikis as their internal collaboration tool. With the global Internet, people of all walks of life can participate in wikis and add their own perspectives and knowledge to a shared resource.
  • Podcasting: Podcasting is an audio-based medium that originally enabled people to record audio and convert it for use. 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 other mobile devices.
  • Peer-to-peer (P2P) file sharing: Peer-to-peer file sharing allows people to share files with each other without having to store and download them from a central server. The user joins the P2P network by simply installing the P2P software. This lets the user locate and share files with others in the P2P network. The widespread digitization of media files, such as music and video files, has increased the interest in P2P file sharing. P2P file sharing has not been embraced by everyone. Many people are concerned about violating the laws of copyrighted materials.

What other sites or tools do you use to share your thoughts?

Networks Support the Way We Work (

Networks provide fast, reliable access to business resources regardless of the geographic location of the employee.

Changing the Way We Work

In the business world, data networks were initially used by businesses to internally record and manage financial information, customer information, and employee payroll systems. These business networks evolved to enable the transmission of many different types of information services, including email, video, messaging, and telephony.

The use of networks to provide efficient and cost-effective employee training is increasing in acceptance. Online learning opportunities can decrease time-consuming and costly travel yet still ensure that all employees are adequately trained to perform their jobs in a safe and productive manner.

There are many success stories illustrating innovative ways that networks are being used to make us more successful in the workplace. Some of these scenarios are available through the Cisco website at www.cisco.com.

Networks Support the Way We Play (

Networks allow us to locate and interact with others who share common interests.

Changing the Way We Play

The widespread adoption of the Internet by the entertainment and travel industries enhances the ability to enjoy and share many forms of recreation, regardless of location. It is possible to explore places interactively that previously we could only dream of visiting, as well as to preview the actual destinations before making a trip. Travelers can post the details and photographs from their adventures online for others to view.

In addition, the Internet is used for traditional forms of entertainment. We listen to recording artists, preview or view motion pictures, read entire books, and download material for future offline access. Live sporting events and concerts can be experienced as they are happening, or recorded and viewed on demand.

Networks enable the creation of new forms of entertainment, such as online games. Players participate in any kind of online competition that game designers can imagine. We compete with friends and foes around the world in the same manner as if they were in the same room.

Even offline activities are enhanced using network collaboration services. Global communities of interest have grown rapidly. We share common experiences and hobbies well beyond our local neighborhood, city, or region. Sports fans share opinions and facts about their favorite teams. Collectors display prized collections and get expert feedback about them.

Online markets and auction sites provide the opportunity to buy, sell, and trade all types of merchandise.

Whatever form of recreation we enjoy in the human network, networks are improving our experience.

Figure 1-3 illustrates some of the ways that networks support the way that we play. How do you play on the Internet?

Figure 1-3

Figure 1-3 Networks Support the Way We Play

Providing Resources in a Network (1.1.2)

To efficiently provide resources to end users, networks occur in many sizes and forms.

Networks of Many Sizes (

Networks come in all sizes, as shown in Figure 1-4. They can range from simple networks consisting of two computers to networks connecting millions of devices.

Figure 1-4

Figure 1-4 Networks Come in Many Sizes

Simple networks installed in homes enable sharing of resources, such as printers, documents, pictures, and music between a few local computers. Home networks are also used to connect several devices to the Internet.

Home office networks and small office networks are often set up by individuals who work from a home or remote office and need to connect to a corporate network or other centralized resources. Additionally, many self-employed entrepreneurs use home office and small office networks to advertise and sell products, order supplies, and communicate with customers. Communication over a network is usually more efficient and less expensive than traditional forms of communication, such as regular mail or long-distance phone calls.

In businesses and large organizations, networks can be used on an even broader scale to allow employees to provide consolidation, storage, and access to information on network servers. Networks also allow rapid communication such as email, instant messaging, and collaboration among employees. In addition to internal organizational benefits, many organizations use their networks to provide products and services to customers through their connection to the Internet. These networks can have many locations with hundreds or thousands of interconnected computers.

The Internet is the largest network in existence. In fact, the term Internet means a “network of networks.” The Internet is literally a collection of interconnected private and public networks, such as the ones described previously. Businesses, small office networks, and even home networks usually provide a shared connection to the Internet. The Internet connects hundreds of millions of computers worldwide.

It is incredible how quickly the Internet has become an integral part of our daily routines.

Clients and Servers (,

All computers connected to a network that participate directly in network communication are classified as hosts or end devices. Hosts can send and receive messages on the network. In modern networks, end devices can act as a client, a server, or both. The software installed on the computer determines which role the computer plays.

Servers are hosts that have software installed that enable them to provide information, like email or web pages, to other hosts on the network. Each service requires separate server software. For example, a host requires web server software to provide web services to the network.

Clients are computer hosts that have software installed that enable them to request and display the information obtained from the server. An example of client software is a web browser, like Windows Internet Explorer. This client software accesses web pages that are stored on a web server. Other common client software includes Microsoft Outlook, used to access email on a web server, and Windows Explorer, used to access files stored on a file server.

A computer with server software can provide services simultaneously to one or many clients.

Additionally, a single computer can run multiple types of server software. In a home or small business, it might be necessary for one computer to act as a file server, a web server, and an email server.

A single computer can also run multiple types of client software. There must be client software for every service required. With multiple clients installed, a host can connect to multiple servers at the same time. For example, a user can check email and view a web page while instant messaging and listening to Internet radio.

Peer-to-Peer (

Client and server software usually runs on separate computers, but it is also possible for one computer to carry out both roles at the same time. In small businesses and homes, many computers function as the servers and clients on the network. This type of network is called a peer-to-peer network and is illustrated in Figure 1-5.

Figure 1-5

Figure 1-5 Peer-to-Peer Network

The simplest peer-to-peer network consists of two directly connected computers using a wired or wireless connection.

Multiple PCs can also be connected to create a larger peer-to-peer network, but this requires a network device, such as a hub, to interconnect the computers.

Peer-to-peer networks are easy to set up, are less complex, and can be created at lower cost than client-server networks because network devices and dedicated servers might not be required. These networks can be used for simple tasks such as transferring files and sharing printers. Peer-to-peer networks have no centralized administration, are not as secure or scalable as client-server networks, and often suffer from host performance issues if they are acting as both a client and a server at the same time.

In larger businesses, because of the potential for high amounts of network traffic, it is often necessary to have dedicated servers to support the number of service requests.

5. LANs, WANs, and the Internet (1.2) | Next Section Previous Section

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