Understanding Different Types of Networks, Communications Devices, and Transmission Media, Lecture notes of Business

Download Understanding Different Types of Networks, Communications Devices, and Transmission Media and more Lecture notes Business in PDF only on Docsity! Communicating Digital Content: Wired and Wireless Networks and Devices 10 Wired and Wireless Networks and Devices Page 2 Communications The process in which two or more computers or devices transfer data, instructions, and information is known as digital communications. Today, the smallest computers and devices can communicate directly with one another, with hundreds of computers on a corporate network, or with millions of other computers around the globe – often via the Internet. Some communications involve cables and wires; others are sent wirelessly through the air. For successful communications, you need the following:  A sending device that initiates an instruction to transmit data, instructions, or information  A communications device that connects the sending device to transmission media  Transmission media, or a communications channel, on which the data, instructions, or information travel  A communications device that connects the transmission media to a receiving device  A receiving device that accepts the transmission of data, instructions, or information All types of computers and mobile devices serve as sending and receiving devices in a communications system. This includes servers, desktops, laptops, tablets, smartphones, portable media players, handheld game devices, and GPS receivers. Communications devices, such a modems, wireless access points, and routers, connect transmission media to a sending or receiving device. Transmission media can be wired or wireless. This module discusses types of networks, various types of communications lines and devices, as well as transmission media. Networks A network is a collection of computers and devices connected together via communications devices and transmission media. A network can be internal to an organization or span the world by connecting to the Internet. Many home and business users create a network to facilitate communications, share hardware, share data and information, share software, and transfer funds.  Facilitate communications. Using a network, people communicate efficiently and easily via email, Internet messaging, chat rooms, blogs, wikis, online social networks, video calls, online meetings, videoconferences, VoIP, text messaging, and more. Some of these communications occur within an internal network. Other times, they occur globally over the Internet.  Share hardware. Each computer or device on a network can be provided access to hardware on the network. For example, each computer and mobile device user can access a printer on the network, as they need it. Thus, home and business users create networks to save money on hardware expenses.  Share data and information. Any authorized user can access data and information stored on a network. A large company, for example, might have a database of customer information. Any authorized employee can access the database using a computer or mobile device connected to the network. Most businesses use a standard, such as EDI (electronic data interchange), that defines how business documents travel across transmission media. For example, businesses use EDI to send bids and proposals, place and track orders, and send invoices.  Share software. Users connected to a network can access software on the network. To support multiple users’ software access, vendors often sell versions of their software designed to run on a network or as a web app on the Internet. These network and Internet subscription versions usually cost less than buying individual copies of the software for each computer. The license fees for these programs typically are based on the number of users or the number of computers or mobile devices attached to the network.  Transfer funds. Electronic funds transfer (EFT) allows users connected to a network to exchange money from one account to another via transmission media. Other businesses and consumers use EFT. Examples include wire transfers, use of credit cards and debit cards, direct deposit of funds into bank accounts, online banking, and online bill payment. Wired and Wireless Networks and Devices Page 5 To alleviate the problems of incompatibility and ensure that hardware and software components can be integrated into any network, various organizations such as ANSI (American National Standards Institute) and IEEE (Institute of Electrical and Electronics Engineers) propose, develop, and approve network standards. A network standard defines guidelines that specify the way computers access the medium to which they are connected, the type9s) of medium used, the speeds used on different types of networks, and the type(s) of physical cable and/or the wireless technology used. Hardware and software manufacturers design their products to meet the guidelines specified in a particular standard, so that their devices can communicate with the network. A standard that outlines characteristics of how two devices communicate on a network is called a protocol. Specifically, a protocol may define data format, coding schemes, error handling, and the sequence in which data transfers over a network. Network Communications Standards and Protocols Name Type Sample Usage Ethernet Standard LAN Token ring Standard LAN TCP/IP Protocol Internet Wi-Fi Standard Hot spots LTE Standard Mobile phones Bluetooth Protocol Wireless headset UWB Standard Inventory tracking IrDA Standard Remote control RFID Protocol Tollbooth NFC Standard Mobile phone payment Ethernet Ethernet is a network standard that specifies no central computer or device on the network (nodes) should control when data can be transmitted. That is, each node attempts to transmit data when it determines the network is available to receive communications. If two computers or devices on an Ethernet network attempt to send data at the same time, a collision will occur. When this happens, the computers or devices resend their messages until data transfer is successful. The Ethernet standard defines guidelines for the physical configuration of a network (e.g., cabling, network devices, and nodes). Ethernet currently is the most popular network standard for LANs because it is relatively inexpensive and easy to install and maintain. Depending on the transmission media used, Ethernet networks have data transfer rates that range from 10 Mbps for home/small office users to 100 Gbps for enterprise users. Token Ring The token ring standard specifies that computers and devices on the network share or pass a special signal, called a token, in a unidirectional manner and in a preset order. A token is a special series of bits that functions like a ticket. The device with the token can transmit data over the network. Only one token exists per network. This ensures that only one computer transmits data at a time. Although token ring is not as widely used today, many networks use the concept of a token. The token ring standard defines guidelines for the physical configuration of a network (e.g., cabling, network cards, and devices). Some token ring networks connect up to 72 devices. Others use a special type of wiring that allows up to 260 connections. The data transfer rate on a token ring network ranges from 4 Mbps to 16 Mbps. TCIP/IP Short for Transmission Control Protocol/Internet Protocol, TCP/IP is a network protocol that defines how messages (data) are routed from one end of a network to the other. TCIP/IP describes rules for dividing messages into small Wired and Wireless Networks and Devices Page 6 pieces, called packets; providing addresses for each packet; checking for and detecting errors; sequencing packets; and regulating the flow of messages along the network. TCP/IP has been adopted as the network standard for Internet communications. Thus, all hosts on the Internet follow the rules defined in this standard. Internet communications also use other standards, such as the Ethernet standard, as data is routed to its destination. When a computer sends data over the Internet, the data is divided into packets. Each packet contains he data, as well as the recipient (destination), the origin (sender) , and the sequence information used to reassemble the data at the destination. Each packet travels along the fastest individual available path to the recipient’s computer or mobile device via routers. this technique of breaking a message into individual packets, sending the packets along the best route available, and then reassembling the data is called packet switching. Reflect Monitoring Network Traffic Network monitoring software constantly assesses the status of a network and sends an email or text message, usually to the network administrator, when it detects a problem. These messages may state that an outage has occurred, the server’s available memory space is near capacity, a new user account has been added or some other critical event has developed. Monitoring software can measure the amount of network traffic, graph network usage, determine when a specific program uses the network, and show the bandwidth used by each computer or mobile device. On networks that use the TCP/IP protocol, for example, packet sniffer software monitors and logs packet traffic for later analysis. Packet sniffing can detect problems, such as why traffic is flowing slowly. The software can also play a security role, including identifying unusual or excessive network activity. For example, it can flag a remote computer always connected to the network or someone making repeated attempts to sign in to an account. Hackers use packet sniffer software to hijack a computer, which means they capture a user’s packets and then reconstruct the contents of webpages that were visited, obtain user names and passwords, and trace photos and videos viewed. Wi-Fi Computers and devices that have the appropriate wireless capability can communicate via radio waves with other computers or devices using Wi-Fi (Wireless fidelity), which identifies any network based on the 802.11 standards. Developed by IEEE, 802.11 is a series of network standards that specifies how two wireless devices communicate over the air with each other. Common standards includes 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.11ad, and 802.11af, with data transfer rates ranging from 11 Mbps to 7 Gbps. Many devices support multiple standards. For example, a designation of 802.11 ac/b/g/n on a computer, router, or other device indicates it supports those four standards. Wi-Fi sometimes is referred to as wireless Ethernet because it uses techniques similar to the Ethernet standard to specify how physically to configure a wireless network. Thus, Wi-Fi networks easily can be integrated with wired Ethernet networks. When a Wi-Fi network accesses the Internet, it works in conjunction with the TCP/IP network standard. One popular use of the Wi-Fi network standard is in hot spots that offer mobile users the ability to connect to the Internet with their Wi-Fi enabled wireless computers and devices. Many homes and small businesses also use Wi-Fi to network computers and devices wirelessly. In open or outdoor areas free from interference, the computers or devices should be within 300 feet of ta wireless access point or hot spot. In closed areas, the wireless network range is about 100 feet. To obtain communications at the maximum distances you may need to install extra hardware to extend or strengthen a wireless signal. LTE LTE (Long Term Evolution) is a network standard that defines how high-speed cellular transmissions use broadcast radio to transmit data for mobile communications. Developed by the Third Generation Partnership Project (3GPP), LTE has Wired and Wireless Networks and Devices Page 7 the potential of 100 Mbps downstream rate (receiving data) and 30 Mbps upstream rate (sending data). Newer specifications are being developed that potentially can support a 1 Gbps downstream rate and a 500 Mbps upstream rate. Based on the TCP/IP network standard, LTE supports data, messaging, voice, and video transmissions. Many mobile service providers, such as AT&T and Verizon Wireless, offer LTE service. Two competing standards for LTE are WiMax (Worldwide Interoperability for Microwave Access) and UMB (Ultra mobile Broadband). Bluetooth/Tech Feature Bluetooth is a network protocol that defines how two Bluetooth devices use short-range radio waves to transmit data. The data transfers between devices at a rate of up to 3 Mbps. To communicate with each other, Bluetooth devices often must be within about 33 feet but can be extended to about 325 feet with additional equipment. A Bluetooth device contains a small chip that allows it to communicate with other Bluetooth devices. For computers and devices that are not Bluetooth-enabled, you can purchase a Bluetooth wireless port adapter that will convert an existing USB port into a Bluetooth port. Most current operating systems have built-in Bluetooth support. When connecting two devices using Bluetooth, the originating device sends a code to the connecting device. The codes must match to establish the connection. Devices that share a Bluetooth connection are said to be paired. Reflect Preventing Bluebugging One reason Bluetooth technology is so popular is because connections generally have low security risks. Despite this advantage security experts have seen an increase in Bluebugging, which occurs when cyberthieves exploit Bluetooth devices that have been paired. Smartphones and other mobile devices are discoverable to other Bluetooth devices only for a short period when they first are turned on, but during this time the hackers can intercept the signals or use hardware that has the same identifying characteristics as the smartphone or other mobile device. Once hackers have intercepted a device, they take control and read or download personal data, place calls, monitor conversations, review txt and email messages, and modify contacts. Security experts recommend the following practices to prevent Bluebugging:  Turn off Bluetooth capability if it is not required. Use a Bluetooth earpiece only when you need o be hands free  Use your device in a remote area. Bluebuggers often work in crowded and public places, such as shopping centers, parks, and public transportation, and they can intercept signals up to 30 feet away from the device.  Prevent hackers from intercepting your device by pairing it for the first time in a secure locations, such as your home.  If Bluetooth is required, be certain the device’s visibility setting is hidden and all paired devices are set to unauthorized so that the user must authorize each connection request.  Upgrade your phone. Older devices are more vulnerable to these intrusions. UWB UWB, (ultra wideband) is a network standard that specifies how two UWB devices use short-range radio waves to communicate at high speeds with each other. At distances of about 33 feet, the data transfer rate is 110 Mbps. At closer distances, such as about 6.5 feet, the transfer rate is at least 480 Mbps. UWB can transmit signals through doors and other obstacles. UWB is best suited for transmission of large files, such as video, graphics, and audio because of its high transfer rates. Examples of UWB uses include locating and tracking inventory, equipment, or personnel (especially in remote or dangerous areas). IrDA Some devices, such as television remote controls, use the IrDA (Infrared Data Association) standard to transmit data wirelessly to each other via infrared (IR) light waves. The devices transfer data at rates from 115 Kbps (thousand bits per second) to 4 Mbps between their IrDA ports. Infrared requires line-of-sight transmission; that is, the sending device and the receiving device must be in line with each other so that nothing obstructs the path of the infrared light wave. Wired and Wireless Networks and Devices Page 10 Wireless Modems Some mobile users have a wireless modem that uses a mobile service provider’s network to connect to the Internet wirelessly from a computer or mobile device. Wireless modems, which have an external or built-in antenna, are available as USB adapters and other devices. Some smartphones also can function as a wireless modem, called a mobile hot spot, when tethered to a personal computer or mobile device. Wireless Access Points A wireless access point (WAP) is a central communications device that allows computers and devices to transfer data wirelessly among themselves or to a wired network using wireless technologies, such as Wi-Fi. Wireless access points have high-quality internal or external antennas for optimal signals. For the best signal, some manufacturers suggest positioning the wireless access point at the highest possible location and using a device to strengthen your wireless signal. A wireless access point either connects to a router via an Ethernet or other cable or is part of a router. Routers A router is a communications device that connects multiple computers or other routers together and transmits data to its correct destination on a network. A router can be used on a network of any size. On the largest scale, routers along the Internet backbone forward data packets to their destination using the fastest available path. For smaller business and home networks, a router allows multiple computers and mobile devices to share a single broadband Internet connection, such as through a cable model or DSL modem. If the network has a separate router, it connects to the router via a cable. Similarly, if the network has a separate wireless access point, it connects to the router via a cable. Many users, however, opt for routers that provide additional functionality:  A wireless router is a device that performs the functions of a router and also a wireless access point.  A broadband router is a device that performs the functions of a router and also a broadband modem  A broadband wireless router is a device that performs the functions of a router, a wireless access point, and a cable or DSL modem.  A mobile broadband wireless router is a device that performs the functions of a router, a wireless access point, and a wireless modem. Consumers use mobile broadband wireless routers to create a mobile hot spot. These combination devices eliminate the need for a separate wireless access point and/or modem on a network. These routers also enable you easily to configure and secure the device against unauthorized access. Although a router may be able to connect more than 200 wired and/or wireless computers and mobile devices, the performance of the router may decline as you add connections. Some mobile service providers limit the number of connections to their mobile broadband wireless routers. Network Cards A network card, sometimes called a network interface card (NIC) is a communications device that enables a computer or device that does not have built-in networking capability to access a network. The network card coordinates the transmission and receipt of data instructions, and information to and from the computer or device containing the network card. Network cards are available in a variety of styles. A network card for a desktop is an adapter card that has a port to which a cable connects. A network card for mobile computers and devices is in the form of a USB adapter or other device. A network card follows the guidelines of a particular network communications standard, such as Ethernet or token ring. Hubs and Switches Today, thousands of computer networks exist, ranging from small networks operated by home users to global networks operated by widespread telecommunications firms. Interconnecting these many types of networks requires various types of communications devices. A hub or switch is a device that provides a central point for cables in a network. Wired and Wireless Networks and Devices Page 11 Larger networks typically use a switch, while smaller networks use a hub. Some hubs and/or switches include routers. That is, the hub or switch receives data from many directions and then forwards it to one or more destinations. Home Networks Many home users connect multiple computers and devices together in a home network. Vendors typically offer home networking packages that include all the necessary hardware and software to network your home using wired or wireless techniques. You no longer need extensive knowledge of networks to set up a home network. For example desktop operating systems often enable you to connect all computers in your house to a home network easily. Planning and Designing Your Home Network As with any network, a home network’s basic purpose is to share resources and connect devices. You can use a home network to share files and folders or to allow multiple devices to share a printer. Transmission Media Transmission media consist of materials or substances capable of carrying one or more communications signals. When you send data from a computer or mobile device, the signal that carries the data ma y travel over various transmission media. This is especially true when the transmission spans a long distance.. Although many media and devices are involved, the entire communications process could take less than one second. Broadband media transmit multiple signals simultaneously. The amount of data, instructions, and information that can travel over transmission media sometimes is called the bandwidth. The higher the bandwidth, the more data transmitted. For transmission of text only, a lower bandwidth is acceptable. For transmission of music, graphics, photos, virtual reality images, or 3-D games, however, you need a higher bandwidth. When the bandwidth is too low for the application, you will notice a considerable slowdown in system performance. Latency, with respect to communications, is the time it takes to signal to travel from one location to another on a network. Several factors that negatively can affect latency include the distance between the two points, the type of transmission media, and the number of nodes through which the data must travel over the network. For best performance, bandwidth should be high and latency low. Reflect Should ISPs Be Allowed to Control Your Internet Usage? ISPs offered customers an Internet connection and exerted no control over how the customer used the connection. This is similar to a phone company, which does not control who a customer calls, the length of a call, or the reason for the call. Online gaming, VoIP, video and audio streaming, and the use of web apps and cloud services led to an increased reliance on the Internet. Because of these increases, ISPs are attempting to regulate and limit their customers’ usage. Capping is a practice ISPs use that provides a certain amount of data usage at the optimal speed. Once a customer has used his or her allotted amount, the customer’s Internet access is restricted, is slowed, or incurs additional costs. Throttling occurs when a network reduces upload and download speeds of certain high-data users at peak times in order not to tie up network resources for a small pool of users. Controversy surrounds capping and throttling practices. Providers argue that caps are necessary to regulate traffic and ensure equal access to the Internet for all of its users. Critics argue that ISPs use limits to unfairly increase customer fees. Legislators are attempting to resolve the issues surrounding net neutrality, which is the concept of an open Internet, accessible to all users, without interference from ISPs or other third-parties. Proposals include standardizing how data transfer rates are measured and involving the Federal Communications Commission (FCC). The FCC would evaluate the regulations to ensure that ISPs intend merely to regulate traffic, rather than make a profit. It would examine whether caps or throttling are appropriate for low-usage times, such as in the middle of the night, and other related issues. Wired and Wireless Networks and Devices Page 12 Physical Transmission Media Physical transmission media use wire, cable, and other tangible materials to send communications signals. These wires and cables typically are used underground or within or between buildings. Ethernet and token ring LANs use physical transmission media. The different types of physical transmission media include: Twisted-Pair Cable, Coaxial Cable and Fiber-Optic Cable Twisted-Pair Cable One of the more widely used transmission media for network cabling and landline phone systems is twisted-pair cable. Twisted-pair cable consists of one or more twisted-pair wires bundled together. Each twisted-pair wire consists of two separate insulated copper wires that are twisted together. The wires are twisted together to reduce noise, which is an electrical disturbance that can degrade communications. Coaxial Cable Coaxial cable consists of a single copper wire surrounded by at least three layers: 1. an insulating material, 2. a woven or braided metal, and 3. a plastic outer coating. CATV network wiring often uses coaxial cable because it can be cabled over longer distances than twisted-pair cable. Most of today’s computer networks, however, do not use coaxial cable because other transmission media, such as fiber- optic cable, transmit signals at faster rates. Fiber-Optic Cable The core of a fiber-optic cable consists of dozens or hundreds of thin strands of glass or plastic that use light to transmit signals. Each strand, called an optical fiber, is as thin as a human hair. Inside the fiber-optic cable, an insulating glass cladding and a protective coating surround each optical fiber. Fiber optic cables have the following advantages over cables that use wire, such as twisted-pair and coaxial cables:  Capability of carrying significantly ore signals than wire cables  Faster data transmission  Less susceptible to noise (interference) from other devices, such as a copy machine  Better security for signals during transmission because they are less susceptible to noise  Smaller size (much thinner and lighter weight) Disadvantages of fiber-optic cable are it costs more than twisted-pair or coaxial cable and can be difficult to install and modify. Despite these limitations, many phone companies replaced original analog phone lines with fiber-optic cables, enabling them to offer fiber-optic Internet access to home and business users. Busses also use fiber-optic cables in high- traffic networks or as the backbone in a network. Wireless Transmission Media Wireless transmission media send communications signals through the air or space. Many users opt for wireless transmission media because it is more convenient than installing cables. In addition to convenience, businesses use wireless transmission media in locations where it is impossible to install cables. Types of wireless transmission media used in communications include infrared, broadcast radio, cellular radio, microwaves, and communications satellites. Infrared Infrared (IR) is a wireless transmission medium that sends signals using infrared light waves. Mobile computers and devices, such as a mouse, printer, and smartphone, may have an IrDA port that enables the transfer to data from one device to another using infrared light waves.