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Explore the Network

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Jan 10, 2018.

Chapter Description

This sample chapter from Introduction to Networks v6 Companion Guide , introduces the platform of data networks upon which our social and business relationships increasingly depend. The material lays the groundwork for exploring the services, technologies, and issues encountered by network professionals as they design, build, and maintain the modern network.

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Introduction to Networks v6 Companion Guide

Introduction to Networks v6 Companion Guide

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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 of 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.

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.

Play the video to view how connected we are.


Go to the online course to view this video.

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 button. 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.

Play the video to watch how the Internet emerged over the last 25 years and see a glimpse into the future! What else do you think we will be able to do using the network as the platform?


Go to the online course to view this video.

No Boundaries (

Advancements in networking technologies are perhaps the most significant changes in the world today. They are helping to create a world in which national borders, geographic distances, and physical limitations become less relevant presenting 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 for 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 have changed 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. 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.

Play the video to see how the classroom is expanding.


Go to the online course to view this video.

Networks Support 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

  • Texting – Texting enables instant real-time communication between two or more people.

  • 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 – Without the constraints of location or time zone, collaboration tools allow individuals to communicate with each other, often across real-time interactive video. The broad distribution of data networks means that people in remote locations can contribute on an equal basis with people in the heart of large population centers.

  • Blogs – Blogs, which is an abbreviation of the word “weblogs,” are web pages that are easy to update and edit. Unlike commercial websites, blogs give anyone a means to communicate their thoughts to a global audience without technical knowledge of web design.

  • 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 may be subject to more extensive review and editing. Many businesses use wikis as their internal collaboration tool.

  • Podcasting – Podcasting allows people to deliver their audio 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. 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 (

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 networks are being used to make us more successful in the workplace. Some of these scenarios are available through the Cisco web site at http://www.cisco.com/web/about/success-stories/index.html.

Networks Support the Way We Play (

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 as if we were all 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.

Whatever form of recreation we enjoy, networks are improving our experience.

How do you play on the Internet?

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. They can range from simple networks consisting of two computers to networks connecting millions of devices. Figure 1-1 shows four classifications of networks based on size:

Figure 1-1

Figure 1-1 Network Sizes

  • Small home networks connect a few computers to each other and the Internet.

  • The Small Office/Home Office or SOHO network enables computers within a home office or a remote office to connect to a corporate network or access centralized, shared resources.

  • Medium to large networks, such as those used by corporations and schools, can have many locations with hundreds or thousands of interconnected computers.

  • The Internet is a network of networks that connects hundreds of millions of computers world-wide.

Simple networks installed in homes enable sharing of resources, such as printers, documents, pictures, and music between a few local computers.

Home office networks and small office networks are often set up by individuals that work from a home or a 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.

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

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 those described above.

Clients and Servers (

All computers connected to a network that participate directly in network communication are classified as hosts. Hosts are also called end devices.

Servers are computers with software that enable them to provide information, like email or web pages, to other end devices on the network. Each service requires separate server software. For example, a server requires web server software in order to provide web services to the network. 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 may be necessary for one computer to act as a file server, a web server, and an email server.

Clients are computers with 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 Chrome or Firefox. A single computer can also run multiple types of client software. For example, a user can check email and view a web page while instant messaging and listening to Internet radio.

Figure 1-2 shows different client and server examples.

Figure 1-2

Figure 1-2 Client/Server Examples

  • Web Client and Server: The Web Server runs web server software and clients use their browser software, such as Windows Internet Explorer, to access web pages on the server.

  • Email Client and Server: The Email Server runs email server software and clients use their mail client software, such as Microsoft Outlook, to access email on the server.

  • File Client and Server: The File Server stores corporate and user files in a central location. The client devices access these files with client software such as Windows Explorer.

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, as shown in Figure 1-3.

Figure 1-3

Figure 1-3 Peer-to-Peer Example

The advantages of peer-to-peer networking:

  • Easy to set up

  • Less complexity

  • Lower cost since network devices and dedicated servers may not be required

  • Can be used for simple tasks such as transferring files and sharing printers

The disadvantages of peer-to-peer networking:

  • No centralized administration

  • Not as secure

  • Not scalable

  • All devices may act as both clients and servers, which can slow their performance

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

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