Chapter 1. Exploring the Network

How do networks affect the way we interact when we learn, work, and play?

How do networks support communication?

What is a converged network?

What are the four requirements for a reliable network?

How are network devices used?

How do local-area network (LAN) devices compare to wide-area network (WAN) devices?

What is the basic structure of the Internet?

How do LANs and WANs interconnect the Internet?

What is the effect of Bring Your Own Device (BYOD) use, online collaboration, video, and cloud computing on a business network?

How do expanding networking trends affect security considerations?

What are the three Cisco enterprise architectures and how do they meet the needs of an evolving network environment?

Internet page 4

instant messaging (IM) page 7

social media page 8

collaboration tools page 8

weblogs (blogs) page 8

wikis page 8

podcasting page 8

peer-to-peer (P2P) file sharing page 8

quality of service (QoS) page 12

converged network page 13

fault tolerant page 15

packets page 17

scalable page 19

security page 21

network service page 24

end devices page 24

host device page 24

intermediary devices page 25

medium (media) page 25

local-area network (LAN) page 29

wide-area network (WAN) page 29

wireless LAN (WLAN) page 29

storage-area network (SAN) page 29

intranet page 32

extranet page 32

cable page 33

DSL page 33

cellular page 33

satellite page 33

dial-up page 34

dedicated leased line page 34

Metro Ethernet page 35

Bring Your Own Device (BYOD) page 36

cloud computing page 40

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

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.

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?

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 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.

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?

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.

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?

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)

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.

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 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.

Consider a hospital built 40 years ago. Back then, hospital rooms were cabled for the data network, telephone network, and video network for televisions. These separate networks were disparate, meaning that they could not communicate with each other, as shown on the left in Figure 1-5.

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 between many different types of devices over the same communications channel and network structure, as shown on the right in Figure 1-5. 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.

On 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.

Not only will voice and video be transmitted over the same network, the devices that perform the telephone switching and video broadcasting will 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. 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.

As networks evolve, we are discovering that there are four basic characteristics that the underlying architectures need to address in order to meet user expectations:

Fault tolerance

Scalability

QoS

Security

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 are 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 alternative 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, are why circuit-switched technology was not optimal for the Internet.

The devices within the network itself are typically unaware of the content of the individual packets. The only packet information used by intermediate devices is the original source address and the final destination address. These addresses are often referred to as IP addresses, 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. 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 may 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.

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.

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.

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, may 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.

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 communications 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 1-10. 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.

Achieving the required QoS by managing the delay and packet loss parameters on a network becomes the secret to providing a successful solution for end-to-end application quality. One way 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. 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.

Examples of priority decisions for an organization might include

Time-sensitive communication: Increase priority for services like telephony or video distribution

Non-time-sensitive communication: Decrease priority for web page retrieval or email

High importance to organization: Increase priority for production control or business transaction data

Undesirable communication: Decrease priority or block unwanted activity, like peer-to-peer file sharing or live entertainment

Network outages that prevent communications and transactions from occurring, with consequent loss of business

Intellectual property (research ideas, patents, or designs) that is stolen and used by a competitor

Personal or private information that is compromised or made public without the user’s consent

Misdirection and loss of personal or business funds

Loss of important data that takes a significant labor to replace, or is irreplaceable

There are two types of network security concerns that must be addressed: network infrastructure security and information security.

Securing a network infrastructure includes physically securing devices that provide network connectivity, and preventing unauthorized access to the management software that resides on those devices.

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 prevent the following:

Unauthorized disclosure

Theft of information (see Figure 1-11)

Unauthorized modification of information

Denial of service (DoS)

In order to achieve the goals of network security, there are three primary requirements:

Ensuring confidentiality: Data confidentiality means that only the intended and authorized recipients—individuals, processes, or devices—can access and read data. This is accomplished by having a strong system for user authentication, enforcing passwords that are difficult to guess, and requiring users to change their passwords frequently. Encrypting data, so that only the intended recipient can read it, is also part of confidentiality.

Maintaining communication integrity: Data integrity means having the assurance that the information has not been altered in transmission, from origin to destination. Data integrity can be compromised when information has been corrupted—willfully or accidentally. Data integrity is made possible by requiring validation of the sender and by using mechanisms to validate that the packet has not changed during transmission.

Ensuring availability: Availability means having the assurance of timely and reliable access to data services for authorized users. Network firewall devices, along with desktop and server antivirus software, can ensure system reliability and the robustness to detect, repel, and cope with such attacks. Building fully redundant network infrastructures, with few single points of failure, can reduce the impact of these threats.

The network infrastructure contains three categories of network components:

End devices

Intermediary devices

Network media

Devices and media are the physical elements, or hardware, of the network. Hardware comprises the components of the network platform that typically are visible, such as a laptop, PC, switch, router, wireless access point, or the cabling used to connect the devices. Occasionally, some network components may not be visible. In the case of wireless media, for example, messages are transmitted through the air using invisible radio frequency or infrared waves.

Network components are used to provide services and processes. These services and processes 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.

Some examples of end devices are

Computers (work stations, laptops, file servers, web servers)

Network printers

VoIP phones

TelePresence endpoints

Security cameras

Mobile handheld devices (such as smartphones, tablets, PDAs, and wireless debit/credit card readers and barcode scanners)

A host device is either the source or destination of a message transmitted over the network. In order 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.

In modern networks, a host can act as a client, a server, or both. Software installed on the host determines which role it plays on the network. Servers are hosts that have software installed that enables them to provide information and services, like email or web pages, to other hosts on the network. Clients are hosts that have software installed that enables them to request and display the information obtained from the server.

Examples of intermediary network devices are

Network access devices (switches and wireless access points)

Internetworking devices (routers)

Security devices (firewalls)

The management of data as it flows through the network is also a role of the intermediary devices. 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:

Regenerate and retransmit data signals

Maintain information about which 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 QoS priorities

Permit or deny the flow of data, based on security settings

Modern networks primarily use the following three types of media to interconnect devices and to provide the pathway over which data can be transmitted:

Metallic wires within cables

Glass or plastic fibers (fiber-optic cable)

Wireless transmission

Figure 1-12 shows examples of the three types of physical media.

The signal encoding that must occur for the message to be transmitted is different for each media 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 types have the same characteristics or are appropriate for the same purpose. The criteria for choosing network media are

The distance the media can successfully carry a signal

The environment in which the media is to be installed

The amount of data and the speed at which it must be transmitted

The cost of the media and installation

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 1-13. 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 its accompanying labs, you will learn both how these devices operate and how to perform basic configuration tasks on these devices.

In addition to being able to recognize these representations, you need to understand the specialized terminology that is used when discussing how each of these devices and media connect to each other. Important terms to remember are

Network interface card (NIC): Provides the physical connection to the network at the PC or other host device. The media connecting the PC to the networking device plugs directly into the NIC (also known as a LAN adapter).

Physical port: A connector or outlet on a networking device where the media is connected to a host or other networking device.

Interface: Specialized ports on an internetworking device that connect to individual networks. Because routers are used to interconnect networks, the ports on a router are referred to as network interfaces.

There are two types of topology diagrams:

Physical topology diagram: Identifies the physical location of intermediary devices, configured ports, and cable installation, as shown on the left in Figure 1-14.

Logical topology diagram: Identifies devices, ports, and the IP addressing scheme, as shown on the right in Figure 1-14.

Size of the area covered

Number of users connected

Number and types of services available

Figure 1-15 illustrates the two most common types of network infrastructures:

Local-area network (LAN): A network infrastructure that provides access to users and end devices in a small geographical area.

Wide-area network (WAN): A network infrastructure that provides access to other networks over a wide geographical area.

Other types of networks include

Metropolitan-area network (MAN): A network infrastructure that spans a physical area larger than a LAN but smaller than a WAN (e.g., a city). MANs are typically operated by a single entity, such as a large organization.

Wireless LAN (WLAN): Similar to a LAN but wirelessly interconnects users and endpoints in a small geographical area.

Storage-area network (SAN): A network infrastructure designed to support file servers and provide data storage, retrieval, and replication. It involves high-end servers, multiple disk arrays (called blocks), and Fibre Channel interconnection technology.

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. The administrative control that governs the security and access control policies is enforced on the network level.

LANs provide high-speed bandwidth to internal end devices and intermediary devices.

Specific features of WANs include

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.

As shown in Figure 1-16, the Internet is a worldwide collection of interconnected networks (internetworks or the 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.

The Internet is a conglomerate of networks and is not actually 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 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.

Intranet

Extranet

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 who have authorization. An intranet is basically an internet that is usually only accessible from within the organization.

An organization may publish on its intranet web pages about internal events, health and safety policies, staff newsletters, and staff phone directories. For example, a school may have an intranet that includes class schedule information, online curriculum, and discussion forums. Intranets usually help eliminate paperwork and speed up workflows. An organization’s intranet may be accessible to staff working outside of the organization by using secure connections to the internal network.

An organization may use an extranet to provide secure and safe access to individuals who work for different organizations but require company data. Examples of extranets include

A company providing access to outside suppliers/contractors

A hospital providing a booking system to doctors so they can make appointments for their patients

A local office of education providing budget and personnel information to the schools in its district

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 depending on the ISP and the 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 (SPs). Popular business-class services include business DSL, leased lines, and Metro Ethernet.

Cable: Typically offered by cable television service providers, the Internet data signal is carried on the same coaxial cable that delivers cable television. It provides a high-bandwidth, always-on connection to the Internet. A special cable modem separates the Internet data signal from the other signals carried on the cable and provides an Ethernet connection to a host computer or LAN.

DSL: Provides a high-bandwidth, always-on connection to the Internet. It requires a special high-speed modem that separates the DSL signal from the telephone signal and provides an Ethernet connection to a host computer or LAN. DSL runs over a telephone line, with the line split into three channels. One channel is used for voice telephone calls. This channel allows an individual to receive phone calls without disconnecting from the Internet. A second channel is a faster download channel, used to receive information from the Internet. The third channel is used for sending or uploading information. This channel is usually slightly slower than the download channel. The quality and speed of the DSL connection depends mainly on the quality of the phone line and the distance from your phone company’s central office. The farther you are from the central office, the slower the connection.

Cellular: Cellular Internet access uses a cell phone network to connect. Wherever you can get a cellular signal, you can get cellular Internet access. Performance will be limited by the capabilities of the phone and the cell tower to which it is connected. The availability of cellular Internet access is a real benefit in those areas that would otherwise have no Internet connectivity at all, and for people who are constantly on the go.

Satellite: Satellite service is a good option for homes or offices that do not have access to DSL or cable. Satellite dishes require a clear line of sight to the satellite, so satellite service might not be an option in heavily wooded areas or places with other overhead obstructions. Speeds will vary depending on the contract, though they are generally good. Equipment and installation costs can be high (although check the provider for special deals), with a moderate monthly fee thereafter. The availability of satellite Internet access is a real benefit in those areas that would otherwise have no Internet connectivity at all.

Dial-up telephone: An inexpensive option that uses any phone line and a modem. To connect to the ISP, a user calls the ISP access phone number. The low bandwidth provided by a dial-up modem connection is usually not sufficient for large data transfer, although it is useful for mobile access while traveling. A modem dial-up connection should only be considered when higher-speed connection options are not available.

Many homes and small offices are more commonly being connected directly with fiber-optic cables. This enables an ISP 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?

Common connection options for organizations include

Dedicated leased line: This is a dedicated connection from the service provider to the customer premises. Leased lines are actually reserved circuits that connect geographically separated offices for private voice and/or data networking. The circuits are typically rented at a monthly or yearly rate, which tends to make it expensive. In North America, common leased-line circuits include T1 (1.54 Mbps) and T3 (44.7 Mbps), whereas in other parts of the world they are available in E1 (2 Mbps) and E3 (34 Mbps).

Metro Ethernet: Metro Ethernet is typically available from a provider to the customer premises over a dedicated copper or fiber connection providing bandwidth speeds of 10 Mbps to 10 Gbps. Ethernet over Copper (EoC) is more economical than fiber-optic Ethernet service in many cases, is quite widely available, and reaches speeds of up to 40 Mbps. However, EoC is limited by distance. Fiber-optic Ethernet service delivers the fastest connections available at an economical price per megabit. Unfortunately, there are still many areas where this service is unavailable.

DSL: Business DSL is available in various formats. A popular choice is symmetric DSL (SDSL), which is similar to asymmetric DSL (ADSL) but provides the same upload and download speeds. ADSL is designed to deliver bandwidth at different rates downstream than upstream. For example, a customer getting Internet access may have downstream rates that range from 1.5 to 9 Mbps, whereas upstream bandwidth ranges are from 16 to 640 kbps. ADSL transmissions work at distances up to 18,000 feet (5,488 meters) over a single copper twisted pair.

Satellite: Satellite service can provide a connection when a wired solution is not available. Satellite dishes require a clear line of sight to the satellite. Equipment and installation costs can be high, with a moderate monthly fee thereafter. Connections tend to be slower and less reliable than terrestrial competition, which makes satellite less attractive than other alternatives.

The choice of connection varies depending on geographical location and service provider availability.

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 affect organizations and consumers. Some of the top trends include

Bring Your Own Device (BYOD)

Online collaboration

Video communication

Cloud computing

These trends are interconnected and will continue to build off of 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?

In the past, an employee who needed access to the corporate network would be issued a company-provided device, such as a laptop or PC. These devices were typically expensive and were seen as tools for work. With the growth of consumer devices, and the related drop in cost, employees can be expected to have some of the most advanced tools for personal use. These personal tools include laptops, netbooks, tablets, smartphones, and e-readers. BYOD is about end users having the freedom to use these personal tools to access information and communicate across the corporate network. These can be devices purchased by the employer, devices purchased by the employee, or both. BYOD means any device, with any ownership, used anywhere. Extended connectivity through mobile and remote access to the corporate network gives employees tremendous flexibility and increased productivity.

BYOD is an influential trend that has or will touch every IT organization. There are many effects and considerations when providing for a BYOD environment.

Additionally, a complete BYOD solution must consider how to extend the full services of the organization seamlessly, providing the same types of services to a user on a BYOD as are available to a user on a corporate PC. This includes collaboration tools such as integrated voice, video, IM, conferencing, and application sharing.

Finally, the network and applications must be able to offer quality of service regardless of whether the connectivity to those applications or collaboration tools occurs in the main campus, branch office, home office, or mobile teleworker location. Any solution must consider not only the employee using their own device, but also the individuals and applications that they are connecting and communicating with.

Security is a major consideration in a BYOD environment; therefore, any solution must be a highly secure mobile solution. Mobile and remote-access devices are typically not under the same strict control and scrutiny as employer-provided desktop and laptop computers. Therefore, appropriate security and user policies need to be applied to protect corporate data when employees connect with these devices. The range of those policies may vary depending on the spectrum of BYOD access that an organization wants.

Depending on the needs of the organization, a range of BYOD policies may be in place, from limited access to advanced BYOD implementation. Each of these implementations must include end-user agreements that outline the use of personal devices on corporate networks, policies for how and what those devices can access, and guidelines for how lost or stolen devices will be handled. Organizations may also need an agreement about when and if data can be accessed from the personal device of an employee. There have been several legal challenges recently for cases involving an employer who remotely “wiped” an employee-owned device, including both the corporate and personal data it contained. Imagine your surprise as an employee when you discover that by using your new tablet to access the corporate network, you unknowingly agreed to let IT delete your favorite family photos remotely.

For businesses, collaboration is a critical and strategic priority. To remain competitive, organizations must answer three primary collaboration questions:

How can they get everyone on the same page?

With decreased budgets and personnel, how can they balance resources to be in more places at once?

How can they maintain face-to-face relationships with a growing network of colleagues, customers, partners, and peers in an environment that is more dependent on 24-hour connectivity?

One way to answer these questions in today’s environment is through online collaboration tools. In traditional workspaces, and with BYOD environments alike, employees 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. Employees 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, customers, and partners a way to instantly connect, interact, and conduct business, through whatever communications channels they prefer, and achieve business objectives.

End users have high expectations that application performance will be maintained, regardless of time, location, and end device. Users also want to be able to have collaboration capabilities regardless of service provider, meaning they want those capabilities to be available whether they are connecting with collaboration tools across a corporate-maintained network or connecting via their home or hotel Internet connection.

For an organization to be successful in its collaboration strategy, it must determine its collaboration needs and establish which tools effectively meet those needs. Additionally, an organization must be able to prioritize traffic and effectively monitor and manage the performance of those collaboration tools. Finally, an organization must consider security requirements for collaboration and establish proper-use policies to ensure corporate data remains secure.

There’s a wide range of collaboration tools available on the market today, including mobile applications, telePresence, and online web-conferencing tools, just to name a few.

Both consumers and businesses are driving this change. Video is becoming a key requirement for effective collaboration as organizations extend across geographical 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 audio conference will coexist with the video conference. 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, may focus on globalization and fast-changing consumer tastes, while the focus of the Chief Information Officer (CIO) may be on cost savings by reducing travel costs of employees who need to meet face-to-face.

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 may be a web browser, and the cloud’s network takes care of the rest.

Cloud computing is another global trend changing the way organizations access and store data. Cloud computing uses cloud-based services to reduce costs and improve business processes. Cloud computing encompasses any subscription-based or pay-per-use service, in real time over the Internet, that extends the capabilities of IT 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.

Cloud computing helps enterprise IT shift spending from large, one-time capital expenditures to ongoing operating expenses. It also allows enterprise IT to share cloud solution assets and provide dynamic, on-demand delivery of services to the enterprise as a whole.

Cloud computing offers the following potential benefits:

Organizational flexibility: Users can access the information anytime and anyplace using a web browser.

Agility and rapid deployment: The IT department can focus on delivering the tools to mine, analyze, and share the information and knowledge from databases, files, and people.

Reduced cost of infrastructure: Technology is moved from on site to a cloud provider, eliminating the cost of hardware and applications.

Refocus of IT resources: Cost savings of hardware and applications can be applied elsewhere.

Creation of new business models: Applications and resources are easily accessible, so companies can react quickly to customer needs. This helps them set strategies to promote innovation while potentially entering new markets.

Public clouds: Cloud-based applications and services offered in a public cloud are made available to the general population. Services may be free or may be offered on a pay-per-use model, such as paying for online storage. A public cloud uses the Internet to provide services.

Private clouds: Cloud-based applications and services offered in a private cloud are intended 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.

Custom clouds: These are clouds built to meet the needs of a specific industry, such as healthcare or media. Custom clouds can be private or public.

Hybrid clouds: A hybrid cloud is made up of two or more clouds (for example, part custom and part public), where each part remains a distinctive object but both parts 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.

Redundant data communications connections

High-speed virtual servers (sometimes referred to as server farms or server clusters)

Redundant storage systems (typically use SAN technology)

Redundant or backup power supplies

Environmental controls (e.g., air conditioning, fire suppression)

Security devices

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. Whereas 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 may own a separate data center where patient records are maintained electronically. Smaller organizations that 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.

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

Viruses, worms, and Trojan horses: Malicious software and arbitrary code running on a user device

Spyware and adware: Software installed on a user device that secretly collects information about the user

Zero-day attack, also called zero-hour attack: An attack that occurs on the first day that a vulnerability becomes known

Hacker attack: An attack by a knowledgeable person using software or network vulnerabilities to exploit devices or network resources

Denial of service attack: An attack designed to slow or crash applications and processes on a network device

Data interception and theft: An attack to capture private information from an organization’s network

Identity theft: An attack to steal the login credentials of a user in order to access private data

It is equally important to consider internal threats. There have been many studies that show that the most common data breaches happen because of employees. This can be attributed to lost or stolen devices, accidental misuse by employees, and even malicious insiders. 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. Figure 1-19 depicts threats from internal and external sources.

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, the following:

Antivirus and antispyware: To protect user devices from malicious software.

Firewall filtering: To block unauthorized access to the network. This may include a host-based firewall system that is implemented to prevent unauthorized access to the host device, or a basic filtering service on the home router to prevent unauthorized access from the outside world into the network.

Larger networks and corporate networks often have additional security requirements:

Dedicated firewall system: To provide more advanced firewall capability that can filter large amounts of traffic with more granularity

Access control lists (ACL): To further filter access and traffic forwarding

Intrusion prevention system (IPS): To identify fast-spreading threats, such as zero-day or zero-hour attacks

Virtual private network (VPN): To provide secure access to remote workers

Network security requirements must take into account the network environment, as well as the various applications and the computing requirements. Both home environments and businesses must be able to secure their data, while still allowing for 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.

In order for networks to function efficiently and grow, the network must be built upon a standard 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 to ensure that any device can be connected across any combination of network, increases cost efficiency by integrating network security and management, and improves business processes.

With the constant evolution of networks, Cisco has updated its enterprise architectures and frameworks and has created the following three enterprise architectures to address the new network trends, as shown in Figure 1-20:

Borderless networks architecture

Collaboration architecture

Data center and virtualization architecture

These three enterprise technology architectures can be implemented separately, or combined.

This architecture separates the network functions into four areas of responsibility:

Cisco Borderless End Point/User Services: Connects the various devices to provide access to network services. Devices that can connect to the borderless network can range from PCs to tablets and smartphones.

Cisco Borderless Network Services: Optimizes the network connection and includes wireless access, secure access to corporate assets, and video performance optimization.

Cisco Borderless Network Systems: Spans an organization from initial device network access to connecting devices to the cloud.

Cisco Borderless Infrastructure: Supports services and systems with an infrastructure of scalable and resilient hardware and software.

The borderless network architecture supports a highly secure, high-performing network that is accessible to a wide range of devices. It needs to be flexible enough to scale in its support for future growth in terms of business expansion, including BYOD, mobility, and cloud computing, and must be able to support the growing requirements for online voice and video.

TelePresence: Provides next-generation video conferencing, where everyone, everywhere can be face-to-face and more effective through the most natural and lifelike communications experience available.

Collaboration Applications: Stay connected and productive with voice, video, and web conferencing; messaging; mobile applications; and enterprise social software. For example, Cisco WebEx Meetings enables users to create and attend web conference calls. Users can meet to present ideas, share desktops, work on files together, and collaborate with others. Callers can see one another using webcams, and meetings can be recorded for people who are unable to attend.

Customer Collaboration: Creates the foundation for positive customer service, a primary factor in building a stronger business. An example of this is the Cisco SocialMiner social media customer care solution. It can help companies proactively respond to customers and prospects communicating through public social media networks such as Twitter, Facebook, and other public forums or blogging sites.

Unified Communications: View, optimize, and manage the entire communications system from one screen. With Cisco Unified Communications, organizations can seamlessly manage voice, video, mobility, and presence services between IP endpoints, media-processing devices, Voice over IP (VoIP) gateways, mobile devices, and multimedia applications.

The Cisco Unified Data Center incorporates three main data center technologies:

Cisco Unified Computing: Integrates computing, networking, and storage resources to provide a unique, open, managed system that can scale to hundreds of server blades and thousands of desktops on virtual machines. Cisco Unified Computing reduces infrastructure costs, and can be deployed nearly 90 percent more quickly than traditional server platforms.

Cisco Unified Fabric: Flexible network solutions deliver network services to servers, storage, and applications, providing transparent convergence, scalability, and sophisticated intelligence using Cisco Nexus and Catalyst switches.

Cisco Unified Management: Provides the framework for IT service-creation and self-service capabilities, enabling IT to operate more efficiently and to more quickly offer new services to the business.

At the foundation of all three of these architectures, and in fact, at the foundation of the Internet itself, are routers and switches. Routers and switches transport data, voice, and video communications, allow for wireless access, and provide for security. After a basic network infrastructure with routing and switching is built, organizations can grow their network over time, adding features and functionality in an integrated solution.

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 routed and switched networks, including implementation and verification of connections to remote sites in a WAN. This CCNA curriculum includes lessons that address the basic mitigation of security threats, introduction to wireless networking concepts and terminology, and performance-based skills. This CCNA curriculum also includes the use of various protocols, such as Internet Protocol (IP), Open Shortest Path First (OSPF), Serial Line Interface Protocol (SLIP), Frame Relay, VLANs, Ethernet, access control lists (ACLs), 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.

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, and coworkers.

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 the network must be fault tolerant and 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 is 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 Internetwork Operating System (IOS) used to enable routing and switching in a Cisco network environment.

Class Activity 1.5.1.1: Draw Your Concept of the Internet Now

Lab 1.1.1.8: Researching Network Collaboration Tools

Lab 1.3.3.3: Mapping the Internet

Lab 1.4.3.6: Researching IT and Networking Job Opportunities

1. Which of the following is an example of QoS?

A. Data arrives via different physical media.

B. Intermediate devices deliver all packets along the same physical route.

C. Different types of traffic are delivered according to planned priority.

D. An intermediate device fails and traffic is rerouted and delivered reliably.

2. Fill in the blanks of the sentence with the best terms from the following list (not all of which will be used): fault tolerance, security, QoS, data integrity, and scalability.

The network designer for the small bank needed to plan for the network to double in size over 5 years, requiring her to allow for ____. Of course, all information needed to be kept confidential and safe, so she incorporated __ into the design. She accounted for ___ when she ensured packets arrived with minimal loss or delay, and accounted for ___ by making sure the network would recover quickly if there was a hardware failure.

3. Which type of communications allows for dynamic routing over multiple paths and adaptation to failures in a network?

A. Circuit switching

B. QoS

C. Leased fiber lines for packet delivery

D. Packet-switched, connectionless data communications

4. Employees of an insurance company accessing company data on restricted local-area and wide-area networks is an example of using a(n)

A. Internet

B. Extranet

C. Intranet

D. BYOD nets

5. An organization that allows employees to use their own tablets and notebook computers in a secure environment has implemented which type of network?

A. WAN

B. BYOD

C. QoS

D. Intranet

6. A group of movie critics posting a recording of their weekly radio show about movies is an example of

A. Podcasting

B. Webhosting

C. Blogging

D. A wiki

7. When instructors provide common space on a computer to create and share documents they can access on their mobile devices or desktops, they are using:

A. Podcasts

B. Instant messaging

C. Social media

D. Collaboration tools

8. The complexity of a message can affect successful communication across a network. The level of complexity in a message is considered a(n):

A. Switching factor

B. External factor

C. Internal factor

D. Routing factor

9. Which of the following describes a converged network?

A. A network that enables people in different countries to work together in the cloud

B. A network that allows songs and videos to be shared peer to peer

C. A network that carries voice, video, and data traffic at the same time

D. A network that allows secure access to the Internet from inside a firewall

10. A system that allows communications between local networks around the world is a/the

A. BYOD

B. Internet

C. LANs

D. SAN

11. Which of the following is an intermediary device?

A. Router

B. Hand-held device

C. Security camera

D. Laptop

12. A group of computers connected to store data is which type of network?

A. LAN

B. SAN

C. BYOD

D. WAN

13. What is the function of a WLAN?

A. Wireless connection in a small geographical area

B. Wired connections in a local-area network

C. Worldwide communications between local-area networks

D. Wireless communications across the Internet

14. If there are two DSL customers with consistent line quality, which will have the faster connection speed?

A. The one closest to the cable company

B. They will have the same connection speed

C. The one closest to the central office

D. The one whose cable modem is on the last mile

15. Which items can be associated with network availability? (Choose three.)

A. Firewall devices

B. Antivirus software

C. Collaboration software

D. Redundant devices