1.0.1 Why should I take this module?
Welcome to Networking Today!
Congratulations! This module starts you on your path to a successful career in Information Technology by giving you a foundational understanding of the creation, operation, and maintenance of networks. As a bonus, you get to dive into networking simulations using Packet Tracer. We promise you will really enjoy it!
1.0.2 What will I learn to do in this module?
Module Title: Networking Today
Module Objective: Explain the advances in modern network technologies.
1.1 Networks Affect our Lives
1.1.1 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.
1.1.2 The Cisco Networking Academy Learning Experience
World changers aren’t born. They are made. Since 1997 Cisco Networking Academy has been working towards a single goal: the educating and skill building of the next generation of talent required for the digital economy.
Click Play to how Cisco Networking Academy to learn how we use technology to make the world a better place.
1.1.3 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.
1.2 Network Components
1.2.1 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.
As mentioned before, clients are a type of host. Clients have software for requesting and displaying the information obtained from the server, as shown in the figure.
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.
|The email server runs email server software. Clients use mail client software, such as Microsoft Outlook, to access email on the server.|
|Web||The web server runs web server software. Clients use browser software, such as Windows Internet Explorer, to access web pages on the server.|
|File||The file server stores corporate and user files in a central location. The client devices access these files with client software such as the Windows File Explorer.|
Client and server software usually run on separate computers, but it is also possible for one computer to be used for 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.
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
1.2.3 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.
Click Play in the figure to see an animation of data flowing through a network.
1.2.4 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.
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.
1.2.5 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.
1.2.6 Check Your Understanding - Network Components
1.3 Network Representations and Topologies
1.3.1 Network Representations
Network architects and administrators must be able to show what their networks will look like. They need to be able to easily see which components connect to other components, where they will be located, and how they will be connected. Diagrams of networks often use symbols, like those shown in the figure, 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. This type of “picture” of a network is known as a topology diagram. The ability to recognize the logical representations of the physical networking components is critical to being able to visualize the organization and operation of a network.
In addition to these representations, specialized terminology is used to describe how each of these devices and media connect to each other:
- Network Interface Card (NIC) – A NIC physically connects the end device to the network.
- Physical Port – A connector or outlet on a networking device where the media connects to an end device or another networking device.
- Interface – Specialized ports on a networking device that connect to individual networks. Because routers connect networks, the ports on a router are referred to as network interfaces.
Note: Often, the terms port and interface are used interchangeably.
1.3.2 Topology Diagrams
Topology diagrams are mandatory documentation for anyone working with a network. They provide a visual map of how the network is connected. There are two types of topology diagrams, physical and logical.
Physical Topology Diagrams
Physical topology diagrams illustrate the physical location of intermediary devices and cable installation, as shown in the figure. You can see that the rooms in which these devices are located are labeled in this physical topology.
Logical Topology Diagrams
Logical topology diagrams illustrate devices, ports, and the addressing scheme of the network, as shown in the figure. You can see which end devices are connected to which intermediary devices and what media is being used.
The topologies shown in the physical and logical diagrams are appropriate for your level of understanding at this point in the course. Search the internet for “network topology diagrams” to see some more complex examples. If you add the word “Cisco” to your search phrase, you will find many topologies using icons that are similar to what you have seen in these figures.
1.3.3 Check Your Understanding - Network Representations and Topologies
1.4 Common Types of Networks
1.4.1 Networks of Many Sizes
Now that you are familiar with the components that make up networks and their representations in physical and logical topologies, you are ready to learn about the many different types of networks.
Networks come in all sizes. They range from simple networks consisting of two computers, to networks connecting millions of devices.
Simple home networks let you share resources, such as printers, documents, pictures, and music, among a few local end devices.
Small office and home office (SOHO) networks allow people to work from home, or a remote office. Many self-employed workers use these types of networks to advertise and sell products, order supplies, and communicate with customers.
Businesses and large organizations use networks to provide consolidation, storage, and access to information on network servers. Networks provide email, instant messaging, and collaboration among employees. Many organizations use their network’s connection to the internet to provide products and services to customers.
The internet is the largest network in existence. In fact, the term internet means a “network of networks”. It is a collection of interconnected private and public networks.
In small businesses and homes, many computers function as both the servers and clients on the network. This type of network is called a peer-to-peer network.
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1.4.2 LANs and WANs
Network infrastructures vary greatly in terms of:
- Size of the area covered
- Number of users connected
- Number and types of services available
- Area of responsibility
The two most common types of network infrastructures are Local Area Networks (LANs), and Wide Area Networks (WANs). A LAN is a network infrastructure that provides access to users and end devices in a small geographical area. A LAN is typically used in a department within an enterprise, a home, or a small business network. A WAN is a network infrastructure that provides access to other networks over a wide geographical area, which is typically owned and managed by a larger corporation or a telecommunications service provider. The figure shows LANs connected to a WAN.
A LAN is a network infrastructure that spans a small geographical area. LANs have specific characteristics:
- LANs interconnect end devices in a limited area such as a home, school, office building, or campus.
- A LAN is usually administered by a single organization or individual. Administrative control is enforced at the network level and governs the security and access control policies.
- LANs provide high-speed bandwidth to internal end devices and intermediary devices, as shown in the figure.
The figure shows a WAN which interconnects two LANs. A WAN is a network infrastructure that spans a wide geographical area. WANs are typically managed by service providers (SPs) or Internet Service Providers (ISPs).
WANs have specific characteristics:
- WANs interconnect LANs over wide geographical areas such as between cities, states, provinces, countries, or continents.
- WANs are usually administered by multiple service providers.
- WANs typically provide slower speed links between LANs.
The internet is a worldwide collection of interconnected networks (internetworks, or internet for short). The figure shows one way to view the internet as a collection of interconnected LANs and WANs.
Some of the LAN examples are connected to each other through a WAN connection. WANs are then connected to each other. The red WAN connection lines represent all the varieties of ways we connect networks. WANs can connect through copper wires, fiber-optic cables, and wireless transmissions (not shown).
The internet is not owned by any individual or group. Ensuring effective communication across this diverse infrastructure requires the application of consistent and commonly recognized technologies and standards as well as the cooperation of many network administration agencies. There are organizations that were developed to help maintain the structure and standardization of internet protocols and processes. These organizations include the Internet Engineering Task Force (IETF), Internet Corporation for Assigned Names and Numbers (ICANN), and the Internet Architecture Board (IAB), plus many others.
Intranets and Extranets
There are two other terms which are similar to the term internet: intranet and extranet.
Intranet is a term often used to refer to a private connection of LANs and WANs that belongs to an organization. An intranet is designed to be accessible only by the organization’s members, employees, or others with authorization.
An organization may use an extranet to provide secure and safe access to individuals who work for a different organization but require access to the organization’s data. Here are some examples of extranets:
- A company that is providing access to outside suppliers and contractors
- A hospital that is providing a booking system to doctors so they can make appointments for their patients
- A local office of education that is providing budget and personnel information to the schools in its district
The figure illustrates the levels of access that different groups have to a company intranet, a company extranet, and the internet.
Check Your Understanding – Common Types of Networks