Many different components are required to allow a network to provide services and resources. These various components work together to ensure that resources are delivered in an efficient manner to those requiring the services. Show
Components of a Network (1.2.1, 1.2.1.1)The network infrastructure contains three categories of network components—devices, media, and services—as shown in Figure 1-6.
 Figure 1-6 Components of the Network Infrastructure The path that a message takes from source to destination can be as simple as a single cable connecting one computer to another or as complex as a network that literally spans the globe. This network infrastructure is the platform that supports the network. It provides the stable and reliable channel over which our communications can occur. Devices (Figure 1-6a) and media (Figure 1-6b) are the physical elements, or hardware, of the network. Hardware is often the visible components of the network platform such as a laptop, PC, switch, router, wireless access point, or the cabling used to connect the devices. Occasionally, some components might not be so visible. In the case of wireless media, messages are transmitted using invisible radio frequency or infrared waves without requiring any physical connecting media. Network components are used to provide services and processes (Figure 1-6c). These are the communication programs, called software, that run on the networked devices. A network service provides information in response to a request. Services include many of the common network applications people use every day, like email-hosting services and web-hosting services. Processes provide the functionality that directs and moves the messages through the network. Processes are less obvious to us but are critical to the operation of networks. End Devices (1.2.1.2)The network devices that people are most familiar with are called end devices, or hosts. These devices form the interface between users and the underlying communication network. Some examples of end devices are
A host device is either the source or destination of a message transmitted over the network. To distinguish one host from another, each host on a network is identified by an address. When a host initiates communication, it uses the address of the destination host to specify where the message should be sent. Data originates with an end device, flows through the network, and arrives at an end device. Messages can take alternate routes through the network between end devices. Intermediary Network Devices (1.2.1.3)Intermediary devices interconnect end devices. These devices provide connectivity and work behind the scenes to ensure that data flows across the network. Intermediary devices connect the individual hosts to the network and can connect multiple individual networks to form an internetwork. Examples of intermediary network devices are
The management of data as it flows through the network is also a role of the intermediary devices. Intermediary devices direct the path of the data but do not generate or change the data content. These devices use the destination host address, in conjunction with information about the network interconnections, to determine the path that messages should take through the network. Processes running on the intermediary network devices perform these functions:
Network Media (1.2.1.4)Communication across a network is carried on a medium. The medium provides the channel over which the message travels from source to destination. Modern networks primarily use three types of media to interconnect devices and to provide the pathway over which data can be transmitted. As shown in Figure 1-7, these media are
Figure 1-7 Network Media The signal encoding that must occur for the message to be transmitted is different for each medium type. On metallic wires, the data is encoded into electrical impulses that match specific patterns. Fiber-optic transmissions rely on pulses of light, within either infrared or visible light ranges. In wireless transmission, patterns of electromagnetic waves depict the various bit values. Different types of network media have different features and benefits. Not all network media have the same characteristics and are appropriate for the same purpose. The criteria for choosing network media are
Network Representations (1.2.1.5)When conveying complex information such as displaying all the devices and media in a large internetwork, it is helpful to use visual representations. A diagram provides an easy way to understand the way the devices in a large network are connected. Such a diagram uses symbols to represent the different devices and connections that make up a network. This type of “picture” of a network is known as a topology diagram. Like any other language, the language of networking uses a common set of symbols to represent the different end devices, network devices, and media, as shown in Figure 1-8. 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. Throughout this course and labs, you will learn both how these devices operate and how to perform basic configuration tasks on these devices.
Figure 1-8 Network Symbols In addition to these representations, specialized terminology is used when discussing how each of these devices and media connect to each other. Important terms to remember are
Topology Diagrams (1.2.1.6)Topology diagrams, as shown in Figure 1-9, are mandatory for anyone working with a network. They provide a visual map of how the network is connected.
Figure 1-9 Network Topologies There are two types of topology diagrams:
LANs and WANs (1.2.2)Network infrastructures can vary greatly in terms of
For this reason, networks are often classified into various types based on a number of characteristics. Types of Networks (1.2.2.1)Figure 1-10 illustrates the two most common types of network infrastructures:
Figure 1-10 LANs and WANs Other types of networks include
Local-Area Networks (1.2.2.2)Local-area networks (LAN) are a network infrastructure that spans a small geographical area. Specific features of LANs include
Wide-Area Networks (1.2.2.3)Wide-area networks (WAN) are a network infrastructure that spans a wide geographical area. WANs are typically managed by service providers (SP) or Internet service providers (ISP). Specific features of WANs include
The Internet (1.2.3, 1.2.3.1)Although there are benefits to using a LAN or WAN, most individuals need to communicate with a resource on another network, outside of the local network within the home, campus, or organization. This is done using the Internet. As shown in Figure 1-11, the Internet is a worldwide collection of interconnected networks (internetworks or internet for short), cooperating with each other to exchange information using common standards. Through telephone wires, fiber-optic cables, wireless transmissions, and satellite links, Internet users can exchange information in a variety of forms.
Figure 1-11 Internet The Internet is a conglomerate of networks and 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 have been developed for the purpose of helping to maintain the structure and standardization of Internet protocols and processes. These organizations include the Internet Engineering Task Force (IETF), the Internet Corporation for Assigned Names and Numbers (ICANN), and the Internet Architecture Board (IAB), plus many others. Intranet and Extranet (1.2.3.2)There are two other terms that are similar to the term Internet: Intranet is a term often used to refer to a private connection of LANs and WANs that belongs to an organization, and is designed to be accessible only by the organization’s members, employees, or others with authorization. Intranets are basically an internet that is usually only accessible from within the organization. Organizations can publish web pages on an intranet about internal events, health and safety policies, staff newsletters, and staff phone directories. For example, schools can have intranets that include information on class schedules, online curricula, and discussion forums. Intranets usually help eliminate paperwork and speed workflows. The intranet can be accessible to staff working outside of the organization by using secure connections to the internal network. An organization can use an extranet to provide secure and safe access to individuals who work for a different organization, but require company data. Examples of extranets include
Figure 1-12 Intranets, Extranets, and the Internet Internet Access Technologies (1.2.4.1)There are many different ways to connect users and organizations to the Internet. Home users, teleworkers (remote workers), and small offices typically require a connection to an Internet service provider (ISP) to access the Internet. Connection options vary greatly between ISP and geographical location. However, popular choices include broadband cable, broadband digital subscriber line (DSL), wireless WANs, and mobile services. Organizations typically require access to other corporate sites and the Internet. Fast connections are required to support business services, including IP phones, video conferencing, and data center storage. Business-class interconnections are usually provided by service providers (SP). Popular business-class services include business DSL, leased lines, and Metro Ethernet. Connecting Remote Users to the Internet (1.2.4.2)Figure 1-13 illustrates some common connection options for small office and home office users, which include
Figure 1-13 Common Internet Connection Options Many homes and small offices are now being connected directly with fiber-optic cables. This enables an Internet service provider to provide higher bandwidth speeds and support more services such as Internet, phone, and TV. The choice of connection varies depending on geographical location and service provider availability. What are your options for connecting to the Internet? Connecting Businesses to the Internet (1.2.4.3)Corporate connection options differ from home user options. Businesses often require higher bandwidth, dedicated bandwidth, and managed services. Connection options available differ depending on the number of service providers located nearby. Figure 1-14 illustrates common connection options for organizations, which include
The choice of connection varies depending on geographical location and service provider availability.
Figure 1-14 Internet Connectivity Options for Businesses Page 2
The network has become a platform for distributing a wide range of services to end users in a reliable, efficient, and secure manner. The Converging Network (1.3.1.1)Modern networks are constantly evolving to meet user demands. Early data networks were limited to exchanging character-based information between connected computer systems. Traditional telephone, radio, and television networks were maintained separately from data networks. In the past, every one of these services required a dedicated network, with different communication channels and different technologies to carry a particular communication signal. Each service had its own set of rules and standards to ensure successful communication. Consider a large school in the early 1990s. Back then, classrooms were cabled for the public announcement network, the telephone network, a video network for televisions, a data network, and perhaps a security network. These separate networks were disparate, meaning that they could not communicate with each other, as shown in Figure 1-15a.
Figure 1-15 Multiple Networks Versus Converged Networks Advances in technology are enabling us to consolidate these different kinds of networks onto one platform, referred to as the converged network. Unlike dedicated networks, converged networks are capable of delivering voice, video streams, text, and graphics among many different types of devices over the same communication channel and network structure, as shown in Figure 1-15b. Previously separate and distinct communication forms have converged onto a common platform. This platform provides access to a wide range of alternative and new communication methods that enable people to interact directly with each other almost instantaneously. In a converged network, there are still many points of contact and many specialized devices, such as personal computers, phones, TVs, and tablet computers, but there is one common network infrastructure. This network infrastructure uses the same set of rules, agreements, and implementation standards. Planning for the Future (1.3.1.2)The convergence of the different types of communications networks onto one platform represents the first phase in building the intelligent information network, as shown in Figure 1-16. We are currently in this phase of network evolution. The next phase will be to consolidate not only the different types of messages onto a single network but to also consolidate the applications that generate, transmit, and secure the messages onto integrated network devices.
Figure 1-16 Intelligent Information Network Not only will voice and video be transmitted over the same network, but the devices that perform the telephone switching and video broadcasting will also be the same devices that route the messages through the network. The resulting communications platform will provide high-quality application functionality at a reduced cost. The pace at which the development of exciting new converged network applications is occurring can be attributed to the rapid growth and expansion of the Internet. With only about 10 billion of potentially 1.5 trillion things currently connected globally, there is vast potential to connect the unconnected through the IoE. This expansion has created a wider audience for whatever message, product, or service can be delivered. The underlying mechanics and processes that drive this explosive growth have resulted in a network architecture that is both capable of supporting changes and able to grow. As the supporting technology platform for living, learning, working, and playing in the human network, the network architecture of the Internet must adapt to constantly changing requirements for a high quality of service and security. The Supporting Network Architecture (1.3.2.1)Networks must support a wide range of applications and services, as well as operate over many different types of cables and devices, which make up the physical infrastructure. The term network architecture, in this context, refers to the technologies that support the infrastructure and the programmed services and rules, or protocols, that move messages across the network. As networks evolve, we are discovering that there are four basic characteristics, as shown in Figure 1-17, that the underlying architectures need to address in order to meet user expectations:
Figure 1-17 Characteristics of a Reliable Network Fault Tolerance in Circuit-Switched Networks (1.3.2.2)With our reliance on networks, certain precautions must be taken to ensure that the network functions as designed, even if things go wrong. Fault ToleranceThe expectation is that the Internet is always available to the millions of users who rely on it. This requires a network architecture that is built to be fault tolerant. A fault-tolerant network is one that limits the impact of a failure so that the fewest number of devices are affected by it. It is also built in a way that allows quick recovery when such a failure occurs. These networks depend on multiple paths between the source and destination of a message. If one path fails, the messages can be instantly sent over a different link. Having multiple paths to a destination is known as redundancy. Circuit-Switched Connection-Oriented NetworksTo understand the need for redundancy, we can look at how early telephone systems worked. When a person made a call using a traditional telephone set, the call first went through a setup process. This process identified the telephone switching locations between the person making the call (the source) and the phone set receiving the call (the destination). A temporary path, or circuit, was created for the duration of the telephone call. If any link or device in the circuit failed, the call was dropped. To reconnect, a new call had to be made, with a new circuit. This connection process is referred to as a circuit-switched process and is illustrated in Figure 1-18.
Figure 1-18 Circuit Switching in a Telephone Network Many circuit-switched networks give priority to existing circuit connections at the expense of new circuit requests. After a circuit is established, even if no communication is occurring between the persons on either end of the call, the circuit remains connected and resources used until one of the parties disconnects the call. Because there are only so many circuits that can be created, it is possible to get a message that all circuits are busy and a call cannot be placed. The cost to create many alternate paths with enough capacity to support a large number of simultaneous circuits, and the technologies necessary to dynamically re-create dropped circuits in the event of a failure, is why circuit-switched technology was not optimal for the Internet. Fault Tolerance in Packet-Switched Networks (1.3.2.3)Because of the technical issues and cost associated with building a fault-tolerant circuit-switched network, network designers turned their attention to packet-switched technologies. Packet-Switched NetworksIn the search for a network that was more fault tolerant, the early Internet designers researched packet-switched networks. The premise for this type of network is that a single message can be broken into multiple message blocks, with each message block containing addressing information to indicate the origination point and final destination. Using this embedded information, these message blocks, called packets, can be sent through the network along various paths, and can be reassembled into the original message when reaching their destination, as illustrated in Figure 1-19.
Figure 1-19 Packet Switching in a Data Network The devices within the network itself are typically unaware of the content of the individual packets. Only visible is the address of the final destination. These addresses are often referred to as IP addresses, which can be represented in a dotted-decimal format, such as 10.10.10.10. Each packet is sent independently from one location to another. At each location, a routing decision is made as to which path to use to forward the packet toward its final destination. This would be like writing a long message to a friend using ten postcards. Each postcard has the destination address of the recipient. As the postcards are forwarded through the postal system, the destination address is used to determine the next path that postcard should take. Eventually, they will be delivered to the address on the postcards. If a previously used path is no longer available, the routing function can dynamically choose the next best available path. Because the messages are sent in pieces, rather than as a single complete message, the few packets that might be lost can be retransmitted to the destination along a different path. In many cases, the destination device is unaware that any failure or rerouting occurred. Using our postcard analogy, if one of the postcards is lost along the way, only that postcard needs to be mailed again. The need for a single, reserved circuit from end to end does not exist in a packet-switched network. Any piece of a message can be sent through the network using any available path. Additionally, packets containing pieces of messages from different sources can travel the network at the same time. By providing a method to dynamically use redundant paths, without intervention by the user, the Internet has become a fault-tolerant method of communication. In our mail analogy, as our postcard travels through the postal system, it will share transportation with other postcards, letters, and packages. For example, one of the postcards might be placed on an airplane, along with lots of other packages and letters that are being transported toward their final destination. Although packet-switched connectionless networks are the primary infrastructure for today’s Internet, there are some benefits to a connection-oriented system like the circuit-switched telephone system. Because resources at the various switching locations are dedicated to providing a finite number of circuits, the quality and consistency of messages transmitted across a connection-oriented network can be guaranteed. Another benefit is that the provider of the service can charge the users of the network for the period of time that the connection is active. The ability to charge users for active connections through the network is a fundamental premise of the telecommunication service industry. Scalable Networks (1.3.2.4)Not only must a network be fault tolerant, but it must also be able to grow to accommodate new users and services. ScalabilityThousands of new users and service providers connect to the Internet each week. For the Internet to support this rapid amount of growth, it must be scalable. A scalable network can expand quickly to support new users and applications without impacting the performance of the service being delivered to existing users. Figure 1-20 shows the structure of the Internet.
Figure 1-20 Internet as a Scalable Network The fact that the Internet is able to expand at the rate that it is, without seriously impacting the performance experienced by individual users, is a function of the design of the protocols and underlying technologies on which it is built. The Internet has a hierarchical layered structure for addressing, for naming, and for connectivity services. As a result, network traffic that is destined for local or regional services does not need to traverse to a central point for distribution. Common services can be duplicated in different regions, thereby keeping traffic off the higher-level backbone networks. Scalability also refers to the ability to accept new products and applications. Although there is no single organization that regulates the Internet, the many individual networks that provide Internet connectivity cooperate to follow accepted standards and protocols. The adherence to standards enables the manufacturers of hardware and software to concentrate on product development and improvements in the areas of performance and capacity, knowing that the new products can integrate with and enhance the existing infrastructure. The current Internet architecture, while highly scalable, might not always be able to keep up with the pace of user demand. New protocols and addressing structures are under development to meet the increasing rate at which Internet applications and services are being added. Providing QoS (1.3.2.5)As new Internet applications and services are added, it becomes increasingly apparent that some mechanism is required to handle the different types of traffic encountered in a converged network. Quality of ServiceQuality of service (QoS) is an ever-increasing requirement of networks today. New applications available to users over internetworks, such as voice and live video transmissions as shown in Figure 1-21, create higher expectations for the quality of the delivered services. Have you ever tried to watch a video with constant breaks and pauses?
Figure 1-21 Types of Traffic Found in a Converged Network Networks must provide predictable, measurable, and at times, guaranteed services. The packet-switched network architecture does not guarantee that all packets that comprise a particular message will arrive on time and in their correct order, or even that they will arrive at all. Networks also need mechanisms to manage congested network traffic. Network bandwidth is the measure of the data-carrying capacity of the network. In other words, how much information can be transmitted within a specific amount of time? Network bandwidth is measured in the number of bits that can be transmitted in a single second, or bits per second (bps). When simultaneous communications are attempted across the network, the demand for network bandwidth can exceed its availability, creating network congestion. The network simply has more bits to transmit than what the bandwidth of the communication channel can deliver. In most cases, when the volume of packets is greater than what can be transported across the network, devices queue, or hold, the packets in memory until resources become available to transmit them, as shown in Figure 1-22. Queuing packets causes delay because new packets cannot be transmitted until previous packets have been processed. If the number of packets to be queued continues to increase, the memory queues fill up and packets are dropped.
Figure 1-22 Using Queues to Prioritize Communication Achieving the required QoS by managing the delay and packet loss parameters on a network becomes the secret to a successful end-to-end application quality solution. One way that this can be accomplished is through classification. To create QoS classifications of data, we use a combination of communication characteristics and the relative importance assigned to the application, as shown in Figure 1-23. We then treat all data within the same classification according to the same rules. For example, communication that is time sensitive, such as voice transmissions, would be classified differently from communication that can tolerate delay, such as file transfers.
Figure 1-23 Importance of Quality of Service (QoS) Examples of priority decisions for an organization might include
Providing Network Security (1.3.2.6)As new users and services are added to the network, it becomes important that measures be taken to ensure that information access is strictly controlled. SecurityThe Internet has evolved from a tightly controlled internetwork of educational and government organizations to a widely accessible means for transmission of business and personal communications. As a result, the security requirements of the network have changed. The network infrastructure, the services, and the data contained on network-attached devices are crucial personal and business assets. Compromising the integrity of these assets could have serious consequences, such as
There are two types of network security concerns that must be addressed: network infrastructure security and information security. Securing a network infrastructure includes the physical securing of devices that provide network connectivity and preventing unauthorized access to the management software that resides on them. Information security refers to protecting the information contained within the packets being transmitted over the network and the information stored on network-attached devices. Security measures taken in a network should
To achieve the goals of network security, there are three primary requirements, as shown in Figure 1-24:
Figure 1-24 Importance of Network Security Page 3
The network environment continues to evolve, providing new experiences and opportunities for end users. The network is now capable of delivering services and applications in a manner that was once only dreamed about. Network Trends (1.4.1)Just as the way we work, play, and learn impacts the network, the availability of a robust reliable network has an impact on our daily lives. New Trends (1.4.1.1)When you look at how the Internet has changed so many of the things people do daily, it is hard to believe that it has only been around for most people for about 20 years. It has truly transformed the way individuals and organizations communicate. For example, before the Internet became so widely available, organizations and small businesses largely relied on print marketing to make consumers aware of their products. It was difficult for businesses to determine which households were potential customers, so businesses relied on mass print marketing programs. These programs were expensive and varied in effectiveness. Compare that to how consumers are reached today. Most businesses have an Internet presence where consumers can learn about their products, read reviews from other customers, and order products directly from the website. Social networking sites partner with businesses to promote products and services. Bloggers partner with businesses to highlight and endorse products and services. Most of this product placement is targeted to the potential consumer, rather than to the masses. There are many predictions about the Internet in the near future, including the following:
As new technologies and end-user devices come to market, businesses and consumers must continue to adjust to this ever-changing environment. The role of the network is transforming to enable the connections of people, devices, and information. There are several new networking trends that will effect organizations and consumers. Some of the top trends include
These trends are interconnected and will continue to build on one another in the coming years. The next couple of topics will cover these trends in more detail. But keep in mind, new trends are being dreamed up and engineered every day. How do you think the Internet will change in the next 10 years? 20 years? Bring Your Own Device (BYOD) (1.4.1.2)The concept of any device, to any content, in any way is a major global trend that requires significant changes to the way devices are used. This trend is known as Bring Your Own Device (BYOD). BYOD is about end users having the freedom to use personal tools to access information and communicate across a business or campus network. With the growth of consumer devices, and the related drop in cost, employees and students can be expected to have some of the most advanced computing and networking tools for personal use. These personal tools include laptops, netbooks, tablets, smartphones, and e-readers. These can be devices purchased by the company or school, purchased by the individual, or both. BYOD means any device, with any ownership, used anywhere. For example, in the past, a student who needed to access the campus network or the Internet had to use one of the school’s computers. These devices were typically limited and seen as tools only for work done in the classroom or in the library. Extended connectivity through mobile and remote access to the campus network gives students tremendous flexibility and more learning opportunities for the student. BYOD is an influential trend that has or will touch every IT organization. Online Collaboration (1.4.1.3)Individuals want to connect to the network, not only for access to data applications but also to collaborate with one another. Collaboration is defined as “the act of working with another or others on a joint project.” For businesses, collaboration is a critical and strategic priority. To remain competitive, organizations must answer three primary collaboration questions:
Collaboration is also a priority in education. Students need to collaborate with assist each other in learning, to develop team skills used in the workforce, and to work together on team-based projects. One way to answer these questions and meet these demands in today’s environment is through online collaboration tools. In traditional workspaces, and with BYOD environments alike, individuals are taking advantage of voice, video, and conferencing services in collaboration efforts. The ability to collaborate online is changing business processes. New and expanding collaboration tools allow individuals to quickly and easily collaborate, regardless of physical location. Organizations have much more flexibility in the way they are organized. Individuals are no longer restricted to physical locations. Expert knowledge is easier to access than ever before. Expansions in collaboration allow organizations to improve their information gathering, innovation, and productivity. Collaboration tools give employees, students, teachers, customers, and partners a way to instantly connect, interact, and conduct business, through whatever communications channels they prefer, and achieve their objectives. Video Communication (1.4.1.4)Another trend in networking that is critical in the communication and collaboration effort is video. Video is being used for communications, collaboration, and entertainment. Video calls are becoming more popular, facilitating communications as part of the human network. Video calls can be made to and from anywhere with an Internet connection, including from home or at work. Video calls and videoconferencing are proving particularly powerful for sales processes and for doing business. Video is a useful tool for conducting business at a distance, both locally and globally. Today, businesses are using video to transform the way they do business. Video helps businesses create a competitive advantage, lower costs, and reduce the impact on the environment by reducing the need to travel. Figure 1-25 shows the trend of video in communication.
Figure 1-25 Trend of Video in Communication Both consumers and businesses are driving this change. Video is becoming a key requirement for effective collaboration as organizations extend across geographic and cultural boundaries. Video users now demand the ability to view any content, on any device, anywhere. Businesses are also recognizing the role of video to enhance the human network. The growth of media, and the new uses to which it is being put, is driving the need to integrate audio and video into many forms of communication. The audioconference will coexist with the videoconference. Collaboration tools designed to link distributed employees will integrate desktop video to bring teams closer together. There are many drivers and benefits for including a strategy for using video. Each organization is unique. The exact mix, and the nature of the drivers for adopting video, will vary from organization to organization, and by business function. Marketing, for example, might focus on globalization and fast-changing consumer tastes, while the chief information officer’s (CIO) focus might be on cost savings by reducing travel costs of employees needing to meet face to face. Some of the drivers for organizations to develop and implement a video solution strategy include
Another trend in video is video on demand and streaming live video. Delivering video over the network lets us see movies and television programs when we want and where we want. Cloud Computing (1.4.1.5)Cloud computing is the use of computing resources (hardware and software) that are delivered as a service over a network. A company uses the hardware and software in the cloud and a service fee is charged. Local computers no longer have to do all the “heavy lifting” when it comes to running network applications. The network of computers that make up the cloud handles them instead. The hardware and software requirements of the user are decreased. The user’s computer must interface with the cloud using software, which can be a web browser, and the cloud’s network takes care of the rest. Cloud computing is another global trend that is changing the way we access and store data. Cloud computing encompasses any subscription-based or pay-per-use service, in real time over the Internet. Cloud computing allows us to store personal files and even back up our entire hard drive on servers over the Internet. Applications such as word processing and photo editing can be accessed using the cloud. For businesses, cloud computing extends IT’s capabilities without requiring investment in new infrastructure, training new personnel, or licensing new software. These services are available on demand and delivered economically to any device anywhere in the world without compromising security or function. The term cloud computing really refers to web-based computing. Online banking, online retail stores, and online music downloading are all examples of cloud computing. Cloud applications are usually delivered to the user through a web browser. Users do not need to have any software installed on their end device. This allows many different kinds of devices to connect to the cloud. Cloud computing offers the following potential benefits:
There are four primary types of clouds: private, public, hybrid, and custom. A private cloud offers applications and services intended only for a specific organization or entity such as the government. A private cloud can be set up using the organization’s private network, though this can be expensive to build and maintain. A private cloud can also be managed by an outside organization with strict access security. Cloud-based services offered in a public cloud are made available to the general population. Services can be free or are offered on a pay-per-use model, such as paying for online storage. The public cloud uses the Internet to provide services. Hybrid clouds are made up of two or more clouds (for example part custom and part public), where each part remains a distinctive object, but both are connected using a single architecture. Individuals on a hybrid cloud would be able to have degrees of access to various services based on user access rights. Custom clouds are built to meet the needs of a specific industry, such as healthcare or media. Custom clouds can be private or public. Data Centers (1.4.1.6)Cloud computing is possible because of data centers. A data center is a facility used to house computer systems and associated components, including
A data center can occupy one room of a building, one or more floors, or an entire building. Modern data centers make use of cloud computing and virtualization to efficiently handle large data transactions. Virtualization is the creation of a virtual version of something, such as a hardware platform, operating system (OS), storage device, or network resources. While a physical computer is an actual discrete device, a virtual machine consists of a set of files and programs running on an actual physical system. Unlike multitasking, which involves running several programs on the same OS, virtualization runs several different OSs in parallel on a single CPU. This drastically reduces administrative and cost overheads. Data centers are typically very expensive to build and maintain. For this reason, only large organizations use privately built data centers to house their data and provide services to users. For example, a large hospital might own a separate data center where patient records are maintained electronically. Smaller organizations, which cannot afford to maintain their own private data center, can reduce the overall cost of ownership by leasing server and storage services from a larger data center organization in the cloud. Technology Trends in the Home (1.4.2.1)Networking trends are not only affecting the way we communicate at work and at school, but they are also changing just about every aspect of the home. The newest home trends include “smart home technology.” This is technology that is integrated into everyday appliances, allowing them to interconnect with other devices, making them more “smart” or automated. For example, imagine being able to prepare a dish and place it in the oven for cooking prior to leaving the house for the day. Imagine that the oven was “aware” of the dish it was cooking and was connected to your calendar of events so that it could determine what time you should be available to eat, and adjust start times and length of cooking accordingly. It could even adjust cooking times and temperatures based on changes in schedule. Additionally, a smartphone or tablet connection gives the user the ability to connect to the oven directly, to make any desired adjustments. When the dish is “available,” the oven sends an alert message to a specified end-user device that the dish is done and warming. This scenario is not far off. In fact, smart home technology is currently being developed for all rooms within a house. Smart home technology will become more of a reality as home networking and high-speed Internet technology becomes more widespread in homes. New home networking technologies are being developed daily to meet these types of growing technology needs. Powerline Networking (1.4.2.2)Powerline networking is an emerging trend for home networking that uses existing electrical wiring to connect devices, as shown in Figure 1-26. The concept of “no new wires” means the ability to connect a device to the network wherever there is an electrical outlet. This saves the cost of installing data cables and adds no cost to the electrical bill. Using the same wiring that delivers electricity, powerline networking sends information by sending data on certain frequencies similar to the technology used for DSL.
Figure 1-26 Powerline Networking Using a HomePlug standard powerline adapter, devices can connect to the LAN wherever there is an electrical outlet. Powerline networking is especially useful when wireless access points cannot be used or cannot reach all the devices in the home. Powerline networking is not designed to be a substitute for dedicated cabling for data networks. However, it is an alternative when data network cables or wireless communications are not a viable option. Wireless Broadband (1.4.2.3)Connecting to the Internet is vital in smart home technology. DSL and cable are common technologies used to connect homes and small businesses to the Internet. However, wireless can be another option in many areas. Wireless Internet Service Provider (WISP)A wireless Internet service provider (WISP) is an ISP that connects subscribers to a designated access point or hot spot using similar wireless technologies found in home wireless local-area networks (WLAN). WISPs are more commonly found in rural environments where DSL or cable services are not available. Although a separate transmission tower might be installed for the antenna, it is common that the antenna is attached to an existing elevated structure such as a water tower or a radio tower. A small dish or antenna is installed on the subscriber’s roof in range of the WISP transmitter. The subscriber’s access unit is connected to the wired network inside the home. From the perspective of the home user, the setup isn’t much different than DSL or cable service. The main difference is that the connection from the home to the ISP is wireless instead of using a physical cable. Wireless Broadband ServiceAnother wireless solution for the home and small businesses is wireless broadband. This uses the same cellular technology used to access the Internet with a smartphone or tablet. An antenna is installed outside the house, providing either wireless or wired connectivity for devices in the home. In many areas, home wireless broadband is competing directly with DSL and cable services. Security Threats (1.4.3.1)Network security is an integral part of computer networking, regardless of whether the network is limited to a home environment with a single connection to the Internet, or as large as a corporation with thousands of users. The network security implemented must take into account the environment, as well as the tools and requirements of the network. It must be able to secure data while still providing the quality of service that is expected of the network. Securing a network involves protocols, technologies, devices, tools, and techniques to secure data and mitigate threats. Many external network security threats today are spread over the Internet. The most common external threats to networks include
It is equally important to consider internal threats. There have been many studies that show that the most common data breaches happen because of internal users of the network. This can be attributed to lost or stolen devices, accidental misuse by employees, and in the business environment, even malicious employees. With the evolving BYOD strategies, corporate data is much more vulnerable. Therefore, when developing a security policy, it is important to address both external and internal security threats. Security Solutions (1.4.3.2)No single solution can protect the network from the variety of threats that exist. For this reason, security should be implemented in multiple layers, using more than one security solution. If one security component fails to identify and protect the network, others still stand. A home network security implementation is usually rather basic. It is generally implemented on the connecting host devices, as well as at the point of connection to the Internet, and can even rely on contracted services from the ISP. In contrast, the network security implementation for a corporate network usually consists of many components built into the network to monitor and filter traffic. Ideally, all components work together, which minimizes maintenance and improves security. Network security components for a home or small office network should include, at a minimum:
In addition to the these items, larger networks and corporate networks often have other security requirements:
Network security requirements must take into account the network environment, as well as the various applications and computing requirements. Both home environments and businesses must be able to secure their data while still providing the quality of service that is expected of each technology. Additionally, the security solution implemented must be adaptable to the growing and changing trends of the network. The study of network security threats and mitigation techniques starts with a clear understanding of the underlying switching and routing infrastructure used to organize network services. Page 4
The role of the network has changed from a data-only network to a system that enables the connections of people, devices, and information in a media-rich, converged network environment. For networks to function efficiently and grow in this type of environment, the network must be built upon a standard network architecture. The network architecture refers to the devices, connections, and products that are integrated to support the necessary technologies and applications. A well-planned network technology architecture helps ensure the connection of any device across any combination of networks. While ensuring connectivity, it also increases cost efficiency by integrating network security and management, and improves business processes. At the foundation of all network architectures, and in fact, at the foundation of the Internet itself, are routers and switches. Routers and switches transport data, voice, and video communications, as well as allow wireless access and provide security. Building networks that support our needs of today and the needs and trends of the future starts with a clear understanding of the underlying switching and routing infrastructure. After a basic routing and switching network infrastructure is built, individuals, small businesses, and organizations can grow their network over time, adding features and functionality in an integrated solution. Page 5
As the use of these integrated, expanding networks increases, so does the need for training for individuals who implement and manage network solutions. This training must begin with the routing and switching foundation. Achieving Cisco Certified Network Associate (CCNA) certification is the first step in helping an individual prepare for a career in networking. CCNA certification validates an individual’s ability to install, configure, operate, and troubleshoot medium-size route and switched networks, including implementation and verification of connections to remote sites in a WAN. The CCNA curriculum also includes basic mitigation of security threats, introduction to wireless networking concepts and terminology, and performance-based skills. This CCNA curriculum includes the use of various protocols, such as IP, Open Shortest Path First (OSPF), Serial Line Interface Protocol, Frame Relay, VLANs, Ethernet, access control lists (ACL), and others. This course helps set the stage for networking concepts and basic routing and switching configurations and is a start on your path for CCNA certification. Page 6
Networks and the Internet have changed the way we communicate, learn, work, and even play. Networks come in all sizes. They can range from simple networks consisting of two computers to networks connecting millions of devices. The Internet is the largest network in existence. In fact, the term Internet means a “network of networks.” The Internet provides the services that enable us to connect and communicate with our families, friends, work, and interests. The network infrastructure is the platform that supports the network. It provides the stable and reliable channel over which communication can occur. It is made up of network components including end devices, intermediate devices, and network media. Networks must be reliable. This means that the network must be fault tolerant, be scalable, provide quality of service, and ensure security of the information and resources on the network. Network security is an integral part of computer networking, regardless of whether the network is limited to a home environment with a single connection to the Internet or as large as a corporation with thousands of users. No single solution can protect the network from the variety of threats that exist. For this reason, security should be implemented in multiple layers, using more than one security solution. The network infrastructure can vary greatly in terms of size, number of users, and number and types of services that are supported on it. The network infrastructure must grow and adjust to support the way the network is used. The routing and switching platform is the foundation of any network infrastructure. This chapter focused on networking as a primary platform for supporting communication. The next chapter will introduce you to the Cisco Internet Operating System (IOS), which is used to enable routing and switching in a Cisco network environment. Page 7
The following activities provide practice with the topics introduced in this chapter. The labs and class activities are available in the companion The Introduction to Networking Lab Manual (ISBN 978-1-58713-312-1). The Packet Tracer Activities PKA files are found in the online course. Class Activities
Labs
Packet Tracer Activities
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What is the name of the network in which the voice video and data are transferred over the same network infrastructure?
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