NET102 Lesson 1 - Introduction to Networks PDF
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This document introduces computer networks, exploring their use in everyday life and how they are transforming our world. It also discusses the evolution of networks from the past to the present and into the future. The document has a section on various kinds of networking.
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LESSON 1. Introduction the Networks A network is simply defined as something that connects things together for a specific purpose. The term network is used in a variety of contexts, including telephone, television, computer, or even people networks (Balchunas, 2014). Networks are rapi...
LESSON 1. Introduction the Networks A network is simply defined as something that connects things together for a specific purpose. The term network is used in a variety of contexts, including telephone, television, computer, or even people networks (Balchunas, 2014). Networks are rapidly transforming our world into a global society. As stated by Cisco Networking Academy (2016), networks are all around us. They provide us with a way to communicate and share information and resources with individuals in the same location or around the world. This requires an extensive array of technologies and procedures that can readily adapt to varying conditions and requirements. Computer Networking 1 Lesson Objectives: At the end of this lesson, you will be able to: 1. Understand how networks are used in everyday life, 2. Explain how to provide resources over network, and 3. Describe the topologies and devices used in networks. Networks in Our Daily Lives As we observed in this generation, most of the individual, network has become part of daily occurrence. In addition, Cisco Networking Academy (2016), among all the essentials for human existence, the need to interact with others ranks just below our need to sustain life. Communication is almost as important to us as our reliance on air, water, food, and shelter. The methods that we used to communicate are constantly changing and evolving due to the creation and interconnection of robust data networks that has had a profound effect on communication, and has become the new platform on which modern communications occur. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Technology Then and Now Imagine a world without the Internet. No more Google, YouTube, instant messaging, Facebook, Wikipedia, online gaming, Netflix, iTunes, and easy access to current information. No more price-comparison websites, avoiding lines by shopping online, or quickly looking up phone numbers and map directions to various locations at the click of a mouse. How different would our lives be without all of this? That was the world we lived in just 15 to 20 years ago. But over the years, data networks have slowly expanded and been repurposed to improve the quality of life for people everywhere. With the help of interconnected networks today, most of the resources are now available Computer Networking 1 through the Internet, which helps us to: 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 Internet phone calls 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, displaying weather and traffic video from webcams check your bank balance and pay bills electronically As illustrated in Figure 1-1, consider the change that have happened in networks and Internet over the last 25 years and the next 25 years. Typically, in fixed computing network environment, if user wants to access or share resources over the network, the user needs to login on his/her computer account. With the emergent of mobile phone and electronic gadgets, the fixed computing environment was transformed into mobile computing environment. In this environment, the user will use his/her personal devices (such as smartphone, laptop, tablet, and etc.) to connect over the wireless networks and to access the systems as well as vital information. Mobile computing environment is also called as bring-your-own-device (BYOD) environment. City College of Calamba Dalubhasaan ng Lungsod ng Calamba As innovators and developers discover new ways to maximized the used the networks or Internet, the Internet of Things (IoT) emerge. The IoT environment makes once "dumb" devices "smarter" by giving them the ability to send data over the Internet, allowing the device to communicate with people and other IoT-enabled things such smart watch, smart TV, traffic lights, and other IP-enabled devices or objects. Then, now consider what changes will happen within the next 25 years. This future holds the Internet of Everything (IoE). The IoE is the future network environment that bringing people, process, data, and things together to make networked connections more relevant and valuable. It is turning information into actions that create new capabilities, richer experiences, and unprecedented economic opportunity for individuals, businesses, and countries (Cisco Computer Networking 1 Networking Academy, 2016). Figure 1-1. Evolution of the Network (courtesy of Cisco Press, 2016) Networks Impacts in our Daily Lives Networks and the Internet have changed everything we do, from the way we learn, to the way we communicate, to how we work, and even how we play. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Changing the Way, We Learn Communication, collaboration, and engagement are fundamental building blocks of education. Institutions are continually striving to enhance these processes to maximize the dissemination of knowledge (Cisco Networking Academy, 2016). Traditionally, learning methods provides two primarily sources of expertise from which the student can obtain information: the textbook and the instructor. These two sources are limited, both in the format and the timing of the presentation. However, having robust and reliable networks have changed the way we learn. It supports and improves student learning experiences where delivery learning material in a wide range of formats including interactive activities, Computer Networking 1 assessments, and feedback as shown in Figure1-2. Figure 1-2. Networks Support the Way We Learn (courtesy of Cisco Press, 2016) In addition, access to rich and high-quality instruction is no longer a problem to the students living in distant area where that instruction is being delivered. As a result, online distance learning has developed to minimized the geographic barriers as well as to improved student opportunity to study elsewhere. Likewise, 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. Furthermore, an online discussion groups and message boards enable a student to collaborate with the instructor, with other students in the class, or even with City College of Calamba Dalubhasaan ng Lungsod ng Calamba students across the world. Finally, with the help of network, blended courses can combine instructor-led classes with online courseware or short courses to provide the best of both delivery methods. Changing the Way, We Communicate Networks allows us to easily communicate with individuals from around the world because it eliminates geographic and time-zone boundaries. Below are some forms of communication modes results of converged and reliable networks include: Instant Messaging (IM)/texting: IM and texting both enable instant real-time communication between two or more people such Facebook Messenger, WeChat, and Computer Networking 1 etc. 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 such as Facebook, Twitter, and etc. Collaboration tools: Collaboration tools give people the opportunity to work together on shared documents such as Google Suite, GitHub, and etc. Weblogs (blogs): Weblogs are web pages that are easy to update and edit such as WordPress, Windows Live Writer, and etc. Wikis: Wikis are web pages that groups of people can edit and view together such as Wikipedia, MediaWiki, and etc. Podcasting: Podcasting is an audio-based medium that originally enabled people to record audio and convert it for use. Peer-to-peer (P2P) file sharing: Peer-to-peer file sharing allows people to share files with each other without having to store and download them from a central server such Emule, BitTorrent, uTorrent, and etc. Changing the Way, We Work Networks provide fast, reliable access to business resources regardless of the geographic location of the employee. In the business world, data networks were initially used by businesses to internally record and manage financial information, customer information, and employee payroll systems. These City College of Calamba Dalubhasaan ng Lungsod ng Calamba business networks evolved to enable the transmission of many different types of information services, including email, video conferencing, messaging, and telephony. The use of networks to provide efficient and cost-effective employee training is increasing in acceptance. Online learning opportunities can decrease time-consuming and costly travel yet still ensure that all employees are adequately trained to perform their jobs in a safe and productive manner (Cisco Networking Academy, 2016). Changing the Way, We Play 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 Computer Networking 1 compete with friends and foes around the world in the same manner as if they were in the same room such as PUBG, ML, LOL, and etc. Figure 1-3. Networks Support the Way We Play (courtesy of Cisco Press, 2016) Providing Resources in a Network Networks of Many Sizes Networks occur in many sizes and forms to efficiently provide resources to end users. Networks come in all sizes that ranges from simple networks consisting of two computers to networks connecting millions of devices. Figure 1-4 shows four classifications of networks based on size: City College of Calamba Dalubhasaan ng Lungsod ng Calamba Small Home Networks (SHN). Type of network that connects a few computers to each other and the Internet. Small Office/Home Office (SOHO). A type of network enables computers within a home office or a remote office to connect to a corporate network or access centralized, shared resources. Medium to Large Networks (MLN). These are types of network used by corporations and schools, can have many locations with hundreds or thousands of interconnected computers. World Wide Networks (WWN). The Internet is a network of networks that connects hundreds of millions of computers world-wide. Computer Networking 1 Figure 1-4. Network Sizes (courtesy of Cisco Press, 2016) In addition, data networks can also be categorized according to distance and location of CPUs, and network name as presented in Table 1-1. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Table 1-1. Data Networks according to distance and location of CPUs, and network name Computer Networking 1 Network Architecture used in Providing Resources As stated by Balchunas (2014), a host refers to any device that is connected to a network. A host can also be defined as any device assigned a network address. A host can serve one or more functions: A host can request data, often referred to as a client. A host can provide data, often referred to as a server. A host can both request and provide data, often referred to as a peer. Because of these varying functions, multiple network architectures have been developed, including Peer-to-Peer, Client/Server, and Mainframe/Terminal. As illustrated in Figure 1-5, a basic peer-to-peer architecture, all hosts on the network can both request and provide data and services. For example, two workstations with installed Windows operating system configured to share files would be considered a peer-to-peer network. The advantages of peer-to-peer networking: Easy to set up Less complexity Lower cost since network devices and dedicated servers may not be required City College of Calamba Dalubhasaan ng Lungsod ng Calamba Can be used for simple tasks such as transferring files and sharing printers The disadvantages of peer-to-peer networking: No centralized administration Not as secure Not scalable All devices may act as both clients and servers, which can slow their performance Computer Networking 1 Figure 1-5. Peer-to-Peer Network Architecture (courtesy of Cisco Press, 2016) Note: An ad hoc network connection is a couple of computers connected via a Universal Serial Bus to transfer files such as Wi-Fi or Bluetooth are also example of peer-to-peer network. In a client/server architecture, hosts are assigned specific roles as depicted in Figure 1- 6. A client hardware or devices contact the server and request to use data or share its other resources with it (ex. laptops and desktop computers). While, the servers are powerful computer or workstation that hosts data and other forms of resources. An example of a client/server network would be a computer terminal/s with Windows operating system (ex. Windows XP, Windows 7, or Windows 10) installed accessing files off of to a server with installed Windows 2012 Server operating system or server with non-Windows network operating system. Examples of various client/server roles include the following: File server allows clients to save data to files and folders on its hard drive. Print server redirects print jobs from clients to specific printers. Application server allows clients to run certain programs on the server and enables multiple users to common applications across the network. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Database server allows authorized clients to view, modify, and/or delete data in a common database. Web Client and Server allows software and clients use their browser software, such as Windows Internet Explorer, Google Chrome to access web pages on the server and uses HTTP (Hypertext Transfer Protocol). The advantages of client-server network architecture: Improved data sharing Integration of services Shared resources amongst different platforms Computer Networking 1 Data processing capability despite the location Easy maintenance More secured The disadvantages of client-server network architecture: Overloaded servers Impact of centralized architecture More expensive Figure 1-6. Client-Server Network Architecture (courtesy of Cisco Press, 2016) City College of Calamba Dalubhasaan ng Lungsod ng Calamba Note: A peer-to-peer network is decentralized, because resources and administration are handled locally on each participating machine, while a client/server network can be either centralized or decentralized. Network Topology Diagrams Topology diagrams are mandatory for anyone working with a network. They provide a visual map of how the network is connected. This diagram is usually schematic description of the arrangement of a network, including its nodes and connecting lines. There are two (2) ways of defining network geometry: the physical topology and the logical (or signal) topology. Computer Networking 1 A physical topology is an actual geometric layout of workstations which identifies the physical location of intermediary devices, configured ports, and cable installation as shown in Figure 1-7. On other hand, logical (or signal) topology refers to the nature of the paths the signals follow from node to node. This identifies devices, ports, and the IP addressing scheme as illustrated in Figure 1-8. Figure 1-7. Physical Topology (courtesy of Cisco Press, 2016) City College of Calamba Dalubhasaan ng Lungsod ng Calamba Computer Networking 1 Figure 1-8. Logical Topology (courtesy of Cisco Press, 2016) Important terms to remember in network topology: 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). Figure 1-9. Network Interface Card (courtesy of Cisco Press, 2016) 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. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Network’s Physical Topology Bus topology. Every workstation is connected to a main cable (known as a trunk or bus) that all systems would connect to (see Figure 1-10). Ring topology. Every workstation is connected in a closed loop configuration (see Figure 1- 11). Token ring protocol is used in a star or ring topology, the signal travels in only one direction, carried by a so-called token from node to node. Star topology. In this topology, a central computer or server is required to which all the workstations are directly connected. Notice that every workstation is indirectly connected to every other through the central computer as shown in Figure 1-12. Hybrid or tree topology. This topology combines bus, ring, and star topologies. Some Computer Networking 1 network professionals call this specific hybrid topology a star-bus topology as illustrated in Figure 1-13. Mesh topology. This topology employs either of two schemes, called full mesh (see Figure 1-14) and partial mesh. o Full mesh topology - each workstation is connected directly to each of the others. o Partial mesh topology - some workstations are connected to all the others, and some are connected only to those other nodes with which they exchange the most data. Figure 1-10. A bus topology (courtesy of Clarke, 2011) City College of Calamba Dalubhasaan ng Lungsod ng Calamba Computer Networking 1 Figure 1-11. Looking at a ring topology (courtesy of Clarke, 2011) Figure 1-12. A star topology uses a central device such as a switch to connect all systems (courtesy of Clarke, 2011) City College of Calamba Dalubhasaan ng Lungsod ng Calamba Computer Networking 1 Figure 1-13. Looking at a hybrid topology (courtesy of Clarke, 2011) Figure 1-14. Looking at a full-mesh topology (courtesy of kencorner.com, 2018) City College of Calamba Dalubhasaan ng Lungsod ng Calamba Network’s Logical Topology Ethernet is a common logical bus topology protocol. LocalTalk is a common logical bus or star topology protocol. Token Ring is an IBM’s proprietary protocol, common logical ring topology protocol. Network Types According to Geographical Location Network infrastructures can be differentiated is various ways. Two of the most common types of network infrastructures are LANs and WANs as illustrated in Figure 1-15. Network Computer Networking 1 infrastructures can vary greatly in terms of: Size of the area covered, Number of users connected, Number and types of services available, and Area of responsibility. Figure 1-15. LANs and WANs (courtesy of Cisco Press, 2016) City College of Calamba Dalubhasaan ng Lungsod ng Calamba Local Area Network (LAN) – A network infrastructure that provides access to users and end devices in a small geographical area, which is typically an enterprise, home, or small business network owned and managed by an individual or IT department as shown in Figure 1-16. Computer Networking 1 Figure 1-16. LANs and WANs (courtesy of Cisco Press, 2016) Specific features of LANs include: 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. LANs provide high-speed bandwidth to internal end devices and intermediary devices. * Wide Area Network (WAN) – A network infrastructure that provides access to other networks over a wide geographical area, which is typically owned and managed by a telecommunications service provider as shown in Figure 1-17. 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. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Figure 1-17. LANs and WANs (courtesy of Cisco Press, 2016) Other types of networks include: Metropolitan Area Network (MAN) – A network infrastructure that spans a physical area Computer Networking 1 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 end points in a small geographical area. Also called Local Area Wireless Network (LAWN). Campus Area Network (CAN): A CAN refers to a series of LANs that are internetworked between several nearby buildings. This is a common type of network that’s used in organizations with facilities that are close to one another, such as when there is a pool of office buildings or a campus. It is larger than a LAN but smaller than a MAN. Storage Area Network (SAN) – A network infrastructure designed to support file servers and provide data storage, retrieval, and replication. Personal Area Network (PAN): A personal area network (PAN) refers to the interconnection of information technology devices or gadgets within the environment of an individual user (typically within 10 meters or 33 feet). These interconnected devices might include laptop computers, PDAs, cellphones, printers, PCs or other wearable computer devices. VPN (Virtual Private Network): This network allows for information to be securely sent across a public or unsecure network, such as the Internet. Common uses of a VPN are to connect branch offices or remote users to a main office. Intranet, Extranet, and Internet 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. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Internet The Internet is a worldwide collection of interconnected networks (internetworks or internet for short). Figure 1-18 one way to view the Internet as a collection of interconnected LANs and WANs. In this part of the lesson, we will be distinguished the different between Internet, Extranet, and Intranet as illustrated in Figure 1-19. 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. Computer Networking 1 Note: The term internet (with a lower case “i”) is used to describe multiple networks interconnected. When referring to the global system of interconnected computer networks or the World Wide Web, the term Internet (with a capital “I”) is used. Figure 1-18. Collection of Interconnected LANs and WANs (courtesy of Cisco Press, 2016) Internet is a corporation of networks and is not actually owned by any individual or group (public). It is world-wide / global system of interconnected computer networks. A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name. Unique IP: 98.138.253.109 then DNS equivalent: yahoo.com City College of Calamba Dalubhasaan ng Lungsod ng Calamba Extranet Extranet is private network that uses Internet technology and the public telecommunication system to securely share part of a business's information or operations with suppliers, vendors, partners, customers, or other businesses. Extranet requires security and privacy which include: firewall server management, the issuance and use of digital certificates or similar means of user authentication, encryption of messages, and the use of virtual private networks (VPNs) that tunnel through the public network. Intranet Computer Networking 1 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. Figure 1-19. Internet, Extranet, and Intranet (courtesy of Cisco Press, 2016) City College of Calamba Dalubhasaan ng Lungsod ng Calamba Internet Connections According to Cisco Networking Academy (2016), the type of connection to the Internet will depend on the type of network being connected. A business network will usually require a connection with more bandwidth than a home network. Internet Access Technologies 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 Computer Networking 1 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 (Cisco Networking Academy, 2016). Connecting Remote Users to the Internet Figure 1-20 illustrates some common connection options for small office and home office users, which include: Digital Subscriber Lines (DSL) – DSL provide a high bandwidth, always on, connection to the Internet. DSL runs over a telephone line. In general, small office and home office users connect using Asymmetrical DSL (ADSL), which means that the download speed is faster than the upload speed. 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. Satellite – The availability of satellite Internet access is a real benefit in those areas that would otherwise have no Internet connectivity at all. Satellite dishes require a clear line of sight to the satellite. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Dial-up Telephone – An inexpensive option that uses any phone line and a modem. 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. Computer Networking 1 Figure 1-20. Common Internet Connection Options (courtesy of Cisco Press, 2016) 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 (Cisco Network Academy, 2016). Connecting Businesses to the Internet 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 1-21 illustrates common connection options for organizations, which include: Dedicated Leased Line (DLL) - This is a dedicated connection from the service provider to the customer premises. Leased lines are actually reserved circuits that City College of Calamba Dalubhasaan ng Lungsod ng Calamba 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 them expensive. In North America, common leased line circuits include T1 (1.54 Mbps) and T3 (44.7 Mbps), while 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 widely available, and reaches speeds of up to 40 Mbps. However, Ethernet over Copper is limited by distance. Fiber-optic Ethernet Computer Networking 1 service delivers the fastest connections available at an economical megabit-per- second price. Unfortunately, there are still many areas where this service is unavailable. Digital Subscriber Lines (DSL) - Business DSL is available in various formats. A popular choice is symmetric digital subscriber lines (SDSL), which are similar to asymmetric digital subscriber lines (ADSL), but provide 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 might 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 its terrestrial competition, which makes it less attractive than other alternatives. City College of Calamba Dalubhasaan ng Lungsod ng Calamba Figure 1-21. Internet Connectivity Options for Businesses (courtesy of Cisco Press, 2016) Computer Networking 1 Summary 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. Topology diagrams are mandatory for anyone working with a network and it comes in two (2) different types namely: physical and logical or signal topology. 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 choice of internet connection varies depending on geographical location and service provider availability. City College of Calamba Dalubhasaan ng Lungsod ng Calamba