This is part of the CCNA1 Introduction to Networks course. This page will be updated with texts in the future… for now, please refer to my lecture on my YouTube channel.

Networks Affect our Lives

Networks Connect Us

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.

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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 our 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.

The creation of the cloud lets us store documents and pictures and access them anywhere, anytime. So whether we are on a train, in a park, or standing on top of a mountain, we can seamlessly access our data and applications on any device.

Network Components

Host Roles

If you want to be a part of a global online community, your computer, tablet, or smart phone must first be connected to a network. That network must be connected to the internet. This topic discusses the parts of a network. See if you recognize these components in your own home or school network!

All computers that are connected to a network and participate directly in network communication are classified as hosts. Hosts can be called end devices. Some hosts are also called clients. However, the term hosts specifically refers to devices on the network that are assigned a number for communication purposes. This number identifies the host within a particular network. This number is called the Internet Protocol (IP) address. An IP address identifies the host and the network to which the host is attached.

Servers are computers with software that allow 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 many different clients.

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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 an audio stream. The table lists three common types of server software.

Peer-to-Peer

The advantages of peer-to-peer networking:

-Easy to set up
-Less complex
-Lower cost because 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

End Devices

The network devices that people are most familiar with are end devices. To distinguish one end device from another, each end device on a network has an address. When an end device initiates communication, it uses the address of the destination end device to specify where to deliver the message.

An end device is either the source or destination of a message transmitted over the network.

Intermediary Devices

Intermediary devices connect the individual end devices to the network. They can connect multiple individual networks to form an internetwork. These intermediary devices provide connectivity and ensure that data flows across the network.

Intermediary devices use the destination end device address, in conjunction with information about the network interconnections, to determine the path that messages should take through the network. Examples of the more common intermediary devices and a list of functions are shown in the figure.

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Intermediary network devices perform some or all of these functions:
-Regenerate and retransmit communication signals
-Maintain information about what pathways exist through the network and internetwork
-Notify other devices of errors and communication failures
-Direct data along alternate pathways when there is a link failure
-Classify and direct messages according to priorities
-Permit or deny the flow of data, based on security settings

Note: Not shown is a legacy Ethernet hub. An Ethernet hub is also known as a multiport repeater. Repeaters regenerate and retransmit communication signals. Notice that all intermediary devices perform the function of a repeater.

Network Media

Communication transmits across a network on media. The media provides the channel over which the message travels from source to destination.

Modern networks primarily use three types of media to interconnect devices, as shown in the figure:
-Metal wires within cables – Data is encoded into electrical impulses.
-Glass or plastic fibers within cables (fiber-optic cable) – Data is encoded into pulses of light.
-Wireless transmission – Data is encoded via modulation of specific frequencies of electromagnetic waves.

Criteria to consider when choosing network media:
-What is the maximum distance that the media can successfully carry a signal?
-What is the environment in which the media will be installed?
-What is the amount of data and at what speed must it be transmitted?
-What is the cost of the media and installation?

Different types of network media have different features and benefits. Not all network media have the same characteristics, nor are they all appropriate for the same purpose.

Summary of the Module 1

• Through the use of networks, we are connected like never before.
• All computers that are connected to a network and participate directly in network communication are classified as hosts.
• Diagrams of networks often use symbols to represent the different devices and connections that make up a network.
• A diagram provides an easy way to understand how devices connect in a large network.
• The two types of network infrastructures are Local Area Networks (LANs), and Wide Area Networks (WANs).
• SOHO internet connections include cable, DSL, Cellular, Satellite, and Dial-up telephone.
• Business internet connections include Dedicated Leased Line, Metro Ethernet, Business DSL, and Satellite.
• Network architecture refers to the technologies that support the infrastructure and the programmed services and rules, or protocols, that move data across the network.
• There are four basic characteristics of network architecture: Fault Tolerance, Scalability, Quality of Service (QoS), and Security.
• Recent networking trends that affect organizations and consumers: Bring Your Own Device (BYOD), online collaboration, video communications, and cloud computing.
• There are several common external and internal threats to networks.
• Larger networks and corporate networks use antivirus, antispyware, and firewall filtering, but they also have other security requirements: Dedicated firewall systems, Access control lists (ACL), Intrusion prevention systems (IPS), and Virtual private networks (VPN).
• The Cisco Certified Network Associate (CCNA) certification demonstrates your knowledge of foundational technologies.

Lab Files

Lab 1.9.3 – Research IT and Networking Job Opportunities