Home > Articles > Cisco Network Technology > General Networking > Exploring the Modern Computer Network: Types, Functions, and Hardware

Exploring the Modern Computer Network: Types, Functions, and Hardware

Chapter Description

This chapter focuses on networking as a primary platform for supporting communication. It describes types of networks, how they are used, and the type of hardware that runs them.

Communicating in a Network-Centric World (1.1)

Communication methods are constantly evolving, and the changes affect the way we interact with family, friends, and society. This chapter explores how we came to communicate over computer networks.

Interconnecting Our Lives (1.1.1)

In this section we will look at how people use networked computers to learn, work, and play.

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.

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.

Networks connect people and promote unregulated communication. Networks are the platforms on which to run businesses, to address emergencies, to inform individuals, and to support education, science, and government. The Internet is the largest network in existence. In fact, the term Internet means a network of networks. It is actually a collection of interconnected private and public networks. It is incredible how quickly the Internet has become an integral part of our daily routines.

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 finger. 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 video applications
  • 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 by displaying weather and traffic video from webcams
  • Check your bank balance and pay bills electronically

Innovators are figuring out new 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 within the last couple of decades, as depicted in Figure 1-1. Now consider what changes will happen within the next decade. What else do you think we will be able to do using the network as the platform?

Figure 1-1

Figure 1-1 Computing Timeline

The Global Community (

Advancements in networking technologies are perhaps the most significant change agent 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 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 and the Internet have changed everything we do—the way we learn, the way we communicate, 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. Networks now

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

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 (

Changes in network communications have enabled friends, families, and businesses to communicate in ways that could only be imagined by previous generations.

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 communications include

  • Instant messaging (IM) and 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, including those without technical knowledge of web design, a means to communicate their thoughts to a global audience. 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 may 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 enables people to share files with each other without having to store the files on and download them from a central server. The user joins the P2P network by simply installing the P2P software. This lets them 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 that widespread use of P2P has enabled many to violate the laws of copyrighted materials.

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

Networks Support the Way We Work (

Businesses, whether a small family business or a multinational corporation, have changed the way they operate to reap the benefits of network communications.

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 networks are being used to make us more successful in the workplace. Some of these scenarios are available through the Cisco website at http://www.cisco.com.

Networks Support the Way We Play (

Games, music, and TV are all enjoyed in significantly different ways than a decade ago due to changes in network communications.

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 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.

How do you play on the Internet?

Supporting Communication (1.1.2)

This section discusses the various forms of communication, expected communication behaviors, and communication styles.

What Is Communication? (

Communication in our daily lives takes many forms and occurs in many environments. We have different expectations depending on whether we are chatting via the Internet or participating in a job interview. Each situation has its corresponding expected behaviors and styles.

Establishing the Rules

Before beginning to communicate with each other, we establish rules or agreements to govern the conversation. These rules, or protocols, must be followed in order for the message to be successfully delivered and understood. Figures 1-2, 1-3, and 1-4 depict a few of these rules. Among the protocols that govern successful human communication are the following:

  • Identified sender and receiver
  • Agreed-upon method of communicating (face-to-face, telephone, letter, photograph; see Figure 1-2)
  • Common language and grammar (see Figure 1-3)
  • Speed and timing of delivery
  • Confirmation or acknowledgement requirements (see Figure 1-4)

    Figure 1-2

    Figure 1-2 Agreeing on a Communication Method

    Figure 1-3

    Figure 1-3 Agreeing on a Common Language

    Figure 1-4

    Figure 1-4 Confirming a Message

Communication rules may vary according to the context. If a message conveys an important fact or concept, a confirmation that the message has been received and understood is necessary. Less important messages may not require an acknowledgement from the recipient.

The techniques that are used in network communications share these fundamentals with human conversations.

Quality of Communication (

Communication between individuals is determined to be successful when the meaning of the message understood by the recipient matches the meaning intended by the sender. For data networks, we use the same basic criteria to judge success. However, as a message moves through the network, many factors can prevent the message from reaching the recipient or distort its intended meaning. These factors can be either external or internal.

External QoS Factors

The external quality of service (QoS) factors affecting data communications are related to the complexity of the network and the number of devices a message must pass through on its route to its final destination.

External QoS factors affecting the success of communication include

  • 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 communication

QoS will be discussed in greater detail throughout the course.

Internal QoS Factors

Internal QoS factors that interfere with network communications are related to the nature of the message itself. Different types of messages may vary in complexity and importance. Clear and concise messages are usually easier to understand than complex messages. Important communications require more care to ensure that they are delivered and understood by the recipient.

Internal factors affecting successful communications across the network include

  • The size of the message
  • The complexity of the message
  • The importance of the message

Large messages may be interrupted or delayed at different points within the network. A message with a low importance or priority could be dropped if the network becomes overloaded.

Both the internal and external factors that affect the receipt of a message must be anticipated and controlled for network communications to be successful. New innovations in network hardware and software are being implemented to ensure the quality and reliability of network communications.

5. The Network as a Platform (1.2) | Next Section Previous Section