IST chpt 8 communications and Networks
Peer-to-peer (P2P) network
Network in which nodes can act as both servers and clients. For example, one personal computer can obtain files located on another personal computer and also can provide files to other personal computers.
Local area network (LAN)
Network consisting of computers and other devices that are physically near each other, such as within the same building.
Ring network
Network in which each device is connected to two other devices, forming a ring. There is no host computer, and messages are passed around the ring until they reach the correct destination.
Hotspot
Wireless access points that provide Internet access and are often available in public places such as coffee shops, libraries, bookstores, colleges, and universities.
Connectivity
a concept related to using computer networks to link people and resources.
5G (fifth-generation mobile telecommunications)
A cellular network technology being developed to replace 4G networks with speeds that rival home Internet connections.
Server
A host computer with a connection to the Internet that stores document files used to display web pages. Depending on the resources shared, it may be called a file server, printer server, communication server, web server, or database server.
Router
A node that forwards or routes data packets from one network to their destination in another network.
Client
A node that requests and uses resources available from other nodes. Typically, a client is a user's personal computer.
The Wireless Revolution
A revolution that is expected to dramatically affect the way we communicate and use computer technology.
Directory server
A specialized server that manages resources such as user accounts for an entire network.
Mesh network
A topology requiring each node to have more than one connection to the other nodes so that if a path between two nodes is disrupted, data can be automatically rerouted around the failure using another path.
Telephone line
A transmission medium for both voice and data.
Personal area network (PAN)
A type of wireless network that works within a very small area—your immediate surroundings
Strategy
A way of coordinating the sharing of information and resources. The most common network strategies are terminal, peer-to-peer, and client/server networks.
Backbone
All communication travels along a common connecting cable called a bus or a backbone. As information passes along the bus, it is examined by each device on the system board to see if the information is intended for that device.
Bus
All communication travels along a common connecting cable called a bus or a backbone. As information passes along the bus, it is examined by each device on the system board to see if the information is intended for that device.
Host
Also called a server or provider, is a large centralized computer.
Hierarchical network
Also known as a hierarchical network. A topology in which each device is connected to a central node, either directly or through one or more other devices. The central node is then connected to two or more subordinate nodes that in turn are connected to other subordinate nodes, and so forth, forming a treelike structure.
Tree network
Also known as a hierarchical network. A topology in which each device is connected to a central node, either directly or through one or more other devices. The central node is then connected to two or more subordinate nodes that in turn are connected to other subordinate nodes, and so forth, forming a treelike structure.
Network interface card (NIC)
Also known as a network adapter card. Used to connect a computer to one or more computers forming a communication network whereby users can share data, programs, and hardware.
Network administrator
Also known as network manager. Computer professional who ensures that existing information and communication systems are operating effectively and that new ones are implemented as needed. Also responsible for meeting security and privacy requirements.
Fiber-optic service (FiOS)
An Internet connection service that is not yet widely available. Current providers of FiOS include Google and Verizon with speeds faster than cable or DSL connections.
Dial-up service
Antiquated method of connecting to the Internet using telephones and telephone modems, which has been replaced with higher-speed connection services.
Node
Any device connected to a network. For example, a node is a computer, printer, or data storage device and each device has its own address on the network. Also, within hierarchical databases, fields or records are structured in nodes.
Bandwidth
Bandwidth determines how much information can be transmitted at one time. It is a measurement of the communication channel's capacity. There are three bandwidths: voice band, medium band, and broadband.
Low bandwidth
Bandwidth of a standard telephone line. Also known as low bandwidth.
Voiceband
Bandwidth of a standard telephone line. Also known as low bandwidth.
Medium band
Bandwidth of special leased lines, used mainly with minicomputers and mainframe computers.
Broadband
Bandwidth that includes microwave, satellite, coaxial cable, and fiber-optic channels. It is used for very-high-speed computers.
Baseband
Bandwidth used to connect individual computers that are located close to one another. Though it supports high-speed transmission, it can only carry a single signal at a time.
Packet
Before a message is sent on the Internet, it is broken down into small parts called packets. Each packet is then sent separately over the Internet. At the receiving end, the packets are reassembled into the correct order.
Gbps
Billion bits per second
Computer network
Communications system connecting two or more computers and their peripheral devices to exchange information and share resources.
Proxy server
Computer that acts as a gateway or checkpoint in an organization's firewall. See also Firewall.
Digital signal
Computers can only understand digital signals. Before processing can occur within the system unit, a conversion must occur from what we understand to what the system unit can electronically process.
Network gateway
Connection by which a local area network may be linked to other local area networks or to larger networks.
Satellite connection services
Connection services that use satellites and the air to download or send data to users at a rate seven times faster than dial-up connections
T3 lines
Copper lines combined to form higher-capacity options.
Wide area network (WAN)
Countrywide and worldwide networks that use microwave relays and satellites to reach users over long distances.
Virtual private network (VPN)
Creates a secure private connection between a remote user and an organization's internal network. Special VPN protocols create the equivalent of a dedicated line between a user's home or laptop computer and a company server.
Bus network
Each device is connected to a common cable called a bus or backbone, and all communications travel along this bus.
Coaxial cable
High-frequency transmission cable that replaces the multiple wires of telephone lines with a single solid-copper core. It is used to deliver television signals as well as to connect computers in a network.
T1 lines
High-speed lines that support all digital communications, provide very high capacity, and are very expensive.
Network operating system (NOS)
Interactive software between applications and computers coordinating and directing activities between computers on a network. This operating system is located on one of the connected computers' hard disks, making that system the network server.
Domain name server (DNS)
Internet addressing method that assigns names and numbers to people and computers. Because the numeric IP addresses are difficult to remember, the DNS server was developed to automatically convert text-based addresses to numeric IP addresses.
Home network
LAN network for homes allowing different computers to share resources, including a common Internet connection.
Intranet
Like the Internet, it typically provides e-mail, mailing lists, newsgroups, and FTP services, but it is accessible only to those within the organization. Organizations use intranets to provide information to their employees.
Client/server network
Network in which one powerful computer coordinates and supplies services to all other nodes on the network. Server nodes coordinate and supply specialized services, and client nodes request the services.
Star network
Network of computers or peripheral devices linked to a central computer through which all communications pass. Control is maintained by polling. The configuration of the computers looks like a star surrounding and connected to the central computer in the middle.
Asymmetric digital subscriber line (ADSL)
One of the most widely used types of telephone high-speed connections (DSL).
Base station
Or base station. The receiver interprets incoming radio frequencies from a wireless LAN and routes communications to the appropriate devices, which could be separate computers, a shared printer, or a modem.
Wireless access point
Or base station. The receiver interprets incoming radio frequencies from a wireless LAN and routes communications to the appropriate devices, which could be separate computers, a shared printer, or a modem.
Transfer rate
Or transfer speed, is the speed at which modems transmit data, typically measured in bits per second (bps).
Ethernet
Otherwise known as Ethernet bus or Ethernet LAN. The Ethernet bus is the pathway or arterial to which all nodes (PCs, file servers, print servers, web servers, etc.) are connected. All of this is connected to a local area network (LAN) or a wide area network (WAN).
Extranet
Private network that connects more than one organization.
Modulation
Process of converting digital signals to analog signals.
Demodulation
Process performed by a modem in converting analog signals to digital signals.
Digital subscriber line (DSL)
Provides high-speed connection using existing telephone lines.
DS3 lines
Provides support for very high speed, all-digital transmission for large corporations.
Optical carrier (OC)
Provides support for very high speed, all-digital transmission for large corporations.
4G (fourth-generation mobile telecommunications)
Replacing 3G networks in some areas with providers using WiMax and LTE connections to provide faster transmission speeds.
Protocol
Rules for exchanging data between computers. The protocol http:// is the most common.
Firewall
Security hardware and software. All communications into and out of an organization pass through a special security computer, called a proxy server, to protect all systems against external threats.
Cable service
Service provided by cable television companies using existing television cables.
Digital subscriber line (DSL) service
Service provided by telephone companies using existing telephone lines to provide high-speed connections.
Modem
Short for modulator-demodulator. It is a communication device that translates the electronic signals from a computer into electronic signals that can travel over telephone lines.
Analog signals
Signals that represent a range of frequencies, such as the human voice. They are a continuous electronic wave signal as opposed to a digital signal that is either on or off.
Fiber-optic cable
Special transmission cable made of glass tubes that are immune to electronic interference. Data is transmitted through fiber-optic cables in the form of pulses of light.
1G (first-generation mobile telecommunications)
Started in the 1980s using analog signals to provide voice transmission service.
3G (third-generation mobile telecommunications)
Started in the 2000s and provided services capable of effective connectivity to the Internet, marking the beginning of smartphones.
Cellular service provider
Supports voice and data transmission to wireless devices.
Hub
The center or central node for other nodes. This device can be a server or a connection point for cables from other nodes.
Switch
The center or central node for other nodes. This device coordinates the flow of data by sending messages directly between sender and receiver nodes.
Topology
The configuration of a network. The five principal network topologies are ring, bus, star, tree, and mesh.
Megabits per second (Mbps)
The transfer rate of millions of bits per second.
IP address (Internet Protocol address)
The unique numeric address of a computer on the Internet that facilitates the delivery of e-mail.
Sending and receiving devices
These are often a computer or specialized communication device. They originate (send) as well as accept (receive) messages in the form of data, information, and/or instructions.
Data transmission specifications
These are rules and procedures that coordinate the sending and receiving devices by precisely defining how the message will be sent across the communication channel.
Connection devices
These devices act as an interface between the sending and receiving devices and the communication channel. They convert outgoing messages into packets that can travel across the communication channel. They also reverse the process for incoming messages.
Metropolitan area network (MAN)
These networks are used as links between office buildings in a city.
Communication channel
This is the actual connecting or transmission medium that carries the message. This medium can be a physical wire or cable, or it can be wireless
Ethernet cable
Twisted-pair cable commonly used in networks and to connect a variety of components to the system unit.
Cable modem
Type of modem that uses coaxial cable to create high-speed computer connections.
Wireless modem
Typically a small plug-in USB or Express-Card device that provides very portable high-speed connectivity from virtually anywhere.
Wireless wide area network (WWAN) modem
Typically a small plug-in USB or Express-Card device that provides very portable high-speed connectivity from virtually anywhere.
Wireless LAN (WLAN)
Uses radio frequencies to connect computers and other devices. All communications pass through the network's centrally located wireless receiver or base station and are routed to the appropriate devices.
Intrusion detection system (IDS)
Using sophisticated statistical techniques to analyze all incoming and outgoing network traffic, this system works with firewalls to protect an organization's network.
Electronic commerce
buying and selling goods electronically.
Microwave
communication uses high-frequency radio waves. It is sometimes referred to as line-of-sight communication because it can only travel in a straight line. Because the waves cannot bend with the curvature of the earth, they can be transmitted only over relatively short distances. Thus, it is a good medium for sending data between buildings in a city or on a large college campus. For longer distances, the waves must be relayed by means of stations with dishes or antennas.
Cellular
communication uses multiple antennae (cell towers) to send and receive data within relatively small geographic regions (cells). Most cell phones and other mobile devices use cellular networks.
Satellite
communication uses satellites orbiting about 22,000 miles above the earth as microwave relay stations. Many of these are offered by Intelsat, the International Telecommunications Satellite Consortium, which is owned by 114 governments and forms a worldwide communication system. Satellites orbit at a precise point and speed above the earth. They can amplify and relay microwave signals from one transmitter on the ground to another.
Twisted-pair cable
consists of pairs of copper wire that are twisted together. Both standard telephone lines and Ethernet cables use twisted pair.
Global positioning system (GPS)
devices use that information to uniquely determine the geographic location of the device. Available in many automobiles to provide navigational support, these systems are often mounted into the dash with a monitor to display maps and speakers to provide spoken directions. Most of today's cell phones and tablets use GPS technology for handheld navigation.
Communication Systems
electronic systems that transmit data from one location to another.
Communication Channels
essential element of every communication system
Bluetooth
is a short-range radio communication standard that transmits data over short distances of up to approximately 33 feet. Bluetooth is widely used for wireless headsets, printer connections, and handheld devices.
WiMax (Worldwide Interoperability for Microwave Access)
is a wireless standard that extends the range of Wi-Fi networks using microwave connections. it is commonly used by universities and others to extend the capability of existing Wi-Fi networks.
infrared
light waves to communicate over short distances
Wireless Connections
move data through the air. use radio waves to communicate
provides a fast, efficient alternative to traditional mail by sending and receiving electronic documents
Videoconferencing
provides a very-low-cost alternative to long-distance telephone calls using electronic voice and video delivery.
Texting
provides very efficient direct text communication between individuals using short electronic messages.
2G (second-generation mobile telecommunications)
tarted in the 1990s using digital radio signals.
Communications
the process of sharing data, programs, and information between two or more computers. We have discussed numerous applications that depend on communication systems, including
Tbps
trillion bits per second
Wi-Fi (Wireless Fidelity)
uses high-frequency radio signals to transmit data. A number of standards for Wi-Fi exist, and each can send and receive data at a different speed. Most home and business wireless networks use Wi-Fi.
