Chapter 8: Communications and Networks
Physical Connections
- Use a solid medium to connect sending and receiving devices - These connections include: Twisted-Pair Cable, Coaxial Cable, Fiber-Optic Cable
Connectivity
- A concept related to using computer networks to link people and resources - _______ means that you can connect your personal computer to other computer to other computers and information sources almost anywhere - With this connection you are linked to the world of larger computers and the Internet
Coaxial Cable
- A high-frequency transmission cable, 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
Bandwidth
- A measurement of the width or capacity of the communication channel - Effectively, it means how much information can move across the communication channel in a given amount of time - There are four categories of ______: Voiceband/Low _______, Medium Band, Broadband, and Baseband
Client
- A node that requests and uses resources available from other nodes - EX: a _______ is a user's personal computer
Server
- A node that shares resources with other nodes - Dedicated ______ specialize in performing specific tasks
Extranet
- A private network that connects more than one organization - Many organizations use Internet technologies to allow suppliers and others limited access to their networks - The purpose is to increase efficiency and reduce costs
Intranet
- A private network within an organization that resembles the Internet - Like the public Internet, _______ use browsers, websites, and web pages. - Employees find surfing their organizational ______ to be as easy and as intuitive as surfing the Internet
Peer-to-Peer (P2P) Network
- A type of network strategy - In this network, nodes have equal authority and can act as both clients and servers - The most common way to share games, movies, and music over the Internet is to use this type of network - The primary advantage is that they are easy and inexpensive (often free) to set up and use - One disadvantage is the lack of security controls or other common management functions
Client/Server Network
- A type of network strategy - Use central servers to coordinate and supply services to other nodes on the network - The server provides access to resources such as web pages, databases, application software, and hardware - Advantages: the ability to handle very large networks efficiently, and the availability of powerful network management software to monitor and control network activities - The major disadvantages are the cost of installation and maintenance
Tree Network/Hierarchical Network
- A type of network topology - Each device is connected to a central node, either directly or through one or more other devices - The central node is connected to two or more subordinate nodes that in turn are connected to other subordinate nodes, and so forth, forming a treelike structure
Star Network
- A type of network topology - Each device is connected directly to a central network switch - Whenever a node sends a message, it is routed to the switch, which then passes the message along to the intended recipient - It is the most widely used network topology today
Bus Network
- A type of network topology - Each device is connected to a common cable called a bus or backbone, and all communications travel along this bus
Ring Network
- A type of network topology - Each device is connected to two other devices, forming a ring. - When a message is sent, it is passed around the ring until it reaches the intended destination
Mesh Network
- A type of network topology - This topology is the newest type and does not use a specific physical layout (such as a star or a tree) - Rather, this network requires that each node have more than one connection to the other nodes - The resulting pattern forms the appearance of a mesh - If a path between two nodes is somehow disrupted, data can be automatically rerouted around the failure using another path - Wireless technologies are frequently used to build these networks
Personal Area Network (PAN)
- A type of wireless network that works within a very small area- your immediate surroundings - These networks make it possible for wireless devices to interact with each other (bluetooth)
Communication Channels
- An essential element of every communication system - These channels actually carry the data from one computer to another There are two categories of communication channels: Physical Connections and Wireless Connections
Node
- Any device that is connected to a network - EX: computer, printer, or data storage device
Domain Name Server (DNS)
- Because IP addresses are difficult for people to remember and use, a system was developed to automatically convert text-based addresses to numeric IP addresses - This system uses a ______ _______ ______ that converts text-based addresses into IP addresses
Firewall
- Consists of hardware and software that control access to a company's intranet and other internal networks - Most use a software or a special computer called a proxy server - All communications between the company's internal networks and the outside world pass through this server - By evaluating the source and the content of each communication, the proxy server decided whether it is safe to let a particular message or file pass into or out of the organization's network
Twisted-Pair Cable
- Consists of pairs of copper wire that are twisted together - Both standard telephone lines and Ethernet Cables use twisted pair - Ethernet cables are often used in networks can connect a variety of components to the system unit
Modems (Modulator-Demodulator)
- Convert the digital signals to analog signals and vice versa - The ______ enables digital personal computers to communicate across different media, including telephone wires, cable lines, and radio waves
Wide Area Networks (WANs)
- Countrywide and worldwide networks - These networks provide access to regional service (MAN) providers and typically span distances greater than 100 miles
Virtual Private Networks (VPN)
- Create a secure private connection between a remote user and an organization's internal network - Special _____ ______ _______ protocols create the equivalent of a dedicated line between a user's home or laptop computer and a company server - The connection is heavily encrypted, and from the perspective of the user, it appears that the workstation is actually located on the corporate network
Network Architecture
- Describes how a network is arranged and how resources are coordinated and shared - It encompasses a variety of different network specifics, including network topologies and strategies
Wireless Connections
- Do not use a solid substance to connect sending and receiving devices. Rather they move data through the air - Most use radio waves to communicate - Primary technologies used for _______ ______ are: Bluetooth, Wi-Fi (wireless fidelity), Microwave, WiMax (Worldwide Interoperability for Microwave Access), Cellular, and Satellite
Identification
- Every computer on the Internet has a unique numeric address called an IP Address (Internet Protocol Address) - The Internet uses IP addresses to deliver e-mail and to locate websites
Cellular Service Providers
- Including Verizon, AT&T, Sprint, and T-Mobile, support voice and data transmission to wireless devices using cellular networks. These networks have gone through different generations
Packetization
- Information sent or transmitted across the Internet usually travels through numerous interconnected networks - Before the message is sent, it is reformatted or 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
Wireless LAN (WLAN)
- It uses radio frequencies to connect computers and other devices - All communications pass through the network's centrally located wireless access point or base station. - This access point interprets incoming radio frequencies and routes communications to the appropriate devices
Local Area Networks (LAN)
- Networks with nodes that are in close physical proximity - Typically span distances less than a mile and are owned and operated by individual organizations
Sending and Receiving Devices
- One of the four basic elements of a communication system - 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
- One of the four basic elements of a communication system - 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
- One of the four basic elements of a communication system - 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
Communication Channel
- One of the four basic elements of a communication system - 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
Cable Service
- Provided by cable television companies using their existing television cables - These connections are usually faster than DSL
Digital Subscriber Line (DSL) Service
- Provided by telephone companies using existing telephone lines to provide high-speed connections - _____ is much faster than dial-up
Metropolitan Area Networks (MAN)
- Spans distances up to 100 miles - These networks are frequently used as links between office building that are located throughout a city
Transfer Rate
- The speed with which modems transmit data varies. - This speed is typically measured in millions of bits (megabits) per second (Mbps) - The higher the speed, the faster you can send and receive information
DSL (Digital Subscriber Line)
- This modem uses standard phone lines to create a high-speed connection directly to your phone company's offices - These devices are usually external and connect to the system unit using either a USB or an Ethernet port
Cable Modem
- This modem uses the same coaxial cable as your television - A ____ modem creates high-speed connections using the system unit's USB or Ethernet port
Microwave
- This type of communication uses high-frequency radio waves - It is sometimes referred to as line-of-sight communication because they 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 - It is a good medium for sending data between buildings in a city or on a large college campus
Satellite
- This type of communication uses satellites orbiting about 22,000 miles above the earth as microwave relay stations - The major drawback to this type of communication is that bad weather can sometimes interrupt the flow of data
Fiber-Optic Cable
- Transmits data as pulses of light through tiny tubes of glass - Compared to coaxial cable, it is lighter, faster, and more reliable at transmitting data - It is rapidly replacing twisted-pair cable telephone lines
Dial-Up Services
- Use existing telephones and telephone modems to connect to the Internet - This type of service has been replaced by higher-speed connection services including: DSL Service, Cable Service, Fiber-Optic Service (FiOS), Satellite Connection Services, Cellular Service Providers
Voiceband/Low Bandwidth
- Used for standard telephone communication - Personal computers with telephone modems and dial-up service use this bandwidth - While effective for transmitting text documents, it is too slow for many types of transmissions, including high-quality audio and video
Medium Band
- Used in special leased lines to connect midrange computers and mainframes as well as to transmit data over long distances - This bandwidth is capable of very-high-speed data transfer
Infrared
- Uses infrared light waves to communicate over short distances - Like microwave transmissions, ______ is a line-of-sight communication - Because light waves can only travel in a straight line, sending and receiving devices must be in clear view of one another without any obstructions blocking that view (ex: TV remote control)
Satellite Connection Services
- Uses satellites to provide wireless connections - While slower than DSL and cable modems, ________ connections are available almost anywhere using a satellite receiving disk
Broadband
- Widely used for DSL, cable, and satellite connections to the Internet - Several users can simultaneously use a single broadband connection for high speed data transfer
Baseband
- Widely used to connect individual computers that are located close to one another - Like broadband, it is able to support high-speed transmission, however, unlike broadband, it can only carry a single signal at a time
Intrusion Detection Systems (IDS)
- Work with firewalls to protect an organization's network - These systems use sophisticated statistical techniques to analyze all incoming and outgoing network traffic - Using advanced pattern matching and heuristics, an ____ _____ _____ can recognize signs of a network attack and disable access before the intruder can do damage
Computer Network
A communication system that connects two or more computers so that they can exchange information and share resources
Network Administrator
A computer specialist responsible for efficient network operations and implementation of new networks
Network Gateway
A device that allows one LAN to be linked to other LANs or to larger networks
WiMax (Worldwide Interoperability for Microwave Access)
A new standard that extends the range of Wi-Fi networks using microwave connections
Router
A node that forwards or routes data packets from one network to their destination in another network
Bluetooth
A short-range radio communication standard that transmits data over short distances of up to approximately 33 feet
Directory Server
A specialized server that manages resources, such as user accounts, for an entire network
Uplink
A term relating to sending data to a satellite
Home Networks
Allow different computers to share resources, including a common Internet connection
Analog Signals
Because the telephone was originally designed for voice transmission, telephones typically send and receive _____ _______, which are continuous electronic waves
Electronic Commerce
Buying and selling goods electronically
Host
Any computer system connected to a network that provides access to its resources
Switch
Central node that coordinates the flow of data by sending messages directly between sender and receiver nodes
Communications
Computer ________ is the process of sharing data, programs, and information between two or more computers
Digital Signals
Computers send and receive ______ ______, these represent the presence or absence of an electronic pulse- the on/off binary signals
Network Operating Systems (NOS)
Control and coordinate the activities of all computers and other devices on a network
Network Strategies
Define how information and resources are shared
Network Topology
Describes the physical arrangement of the network
Global Positioning System (GPS)
Devices that use information to uniquely determine the geographic location of the device
Communication Systems
Electronic systems that transmit data from one location to another
Fourth-Generation Mobile Telecommunications (4G)
Has begun to replace 3G networks in some areas with providers using LET (Long Term Evolution) connections to provide faster transmission speeds
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
Downlink
Refers to receiving data from a satellite
First-Generation Mobile Telecommunications (1G)
Started in the 1980s using analog radio signals to provide analog voice transmission service
Second-Generation Mobile Telecommunications (2G)
Started in the 1990s using digital radio signals
Third-Generation Mobile Telecommunication (3G)
Started in the 2000s and provided services capable of effective connectivity to the Internet, marking the beginning of smartphones
Modulation
The name of the process of converting from digital to analog
Demodulation
The process of converting from analog to digital
Network Interface Cards (NIC)
These are expansion cards located within the system unit that connect the computer to a network
Cellular
This type of communication uses multiple antennae (cell towers) to send and receive data within relatively small geographic regions (cells)
Wi-Fi (Wireless Fidelity)
Use high-frequency radio signals to transmit data
Hub
previously filled the purpose of a switch by sending a received message to all connected nodes, rather than just the intended node
provides a fast, efficient alternative to traditional mail by sending and receiving electronic documents
