BU250 Chapter Set 3 (6, 7, & 8)

computer network

a system that connects computers and other devices through communications media so that data and information can be transmitted among them

bandwidth

transmission capacity of a network stated in bits per second; ranges from narrowband to broadband

narrowband

relatively low transmission capacity

broadband

relatively high network capacity; transmission capacity of a communications medium that is faster than 25 Mbps for download and 3 Mbps for upload

download

the transmission speed for material coming to you from an Internet server

upload

the transmission speed for material that you upload to an Internet server

* speed
* distance
* cost

networks represent a compromise among what three objectives?

personal area networks (PANs)

short-range networks (typically a few meters) that are used for communication among devices close to one person; can be wired or wireless

local area networks (LANs)

a network that connects two or more communication devices in a limited geographic region, usually within the same building, so that every use device on the network can communicate with every other device; most of these networks use Ethernet

network interface card (NIC)

every device in the LAN has this that allows the device to physically connect to the LAN’s communications medium

file server/network server

a computer that contains various software and data files for a local area network and houses the LAN’s network operating system, which manages the server and routes and manages communications on the network; not required for LANs but many have it

metropolitan area networks (MANs)

relatively large networks that cover a metropolitan area ; fall between LANs and WANs in size

wide area networks (WANs)

a network, generally provided by common carriers (telephone companies, etc.) that covers a wide geographical area; have large capacities and typically combine multiple channels (fiber optic cables, microwave, satellite, etc.); contain routers

router

a communication processor that routes messages from a LAN to the Internet, across several connected LASs, or across a wide area network such as the Internet

enterprise network

an organization’s network, which is composed of interconnected multiple LANs and WANs; contains a backbone network

backbone network

high-speed central networks to which multiple smaller networks (LANs and smaller WANs) connects; contained in the enterprise network

software-defined network (SDN)

an emerging technology that is becoming increasingly important to help organizations manage their data flows across their enterprise networks; decisions that control how network traffic flows across network devices are managed centrally by software; software dynamically adjusts data flows to meet business and application needs

digital signals

discrete pulses that are either on or off representing a series of bits (0s or 1s); used for communication between computer networks; convey information in a binary form that can be interpreted by computers

analog signals

continuous waves that transmit information by altering the amplitude and frequency of the waves

cable modems

modems that operate over coaxial cable (cable TV); offer broadband access to the Internet or to corporate intranets; speeds vary widely; services share bandwidth among subscribers in a locality

dial-up modems

modems that convert signals from analog to digital and vice versa; internet connection method used where broadband is not available; almost extinct in most parts of the world

digital subscriber line (DSL) modems

modems that operate on the same lines as voice telephones and dial-up modems; always maintain a connection, so an Internet connection is immediately available

communications channel

pathway for communicating data from one location to another; consists of cable and broadcast media

wireline media/cable media

communications channels that use physical wires or cables to transmit data and information; includes twisted-pair wire, coaxial cable, and fiber-optic cable

twisted-pair wire

a communications medium consisting of strands of copper wire twisted together in pairs; most prevalent form of communications wiring; connect the backbone to individual devices on the network; inexpensive to purchase, widely available, and easy to work with

* inexpensive
* widely available
* easy to work with

twisted pair-wire advantages

* slow (low bandwidth)
* subject to interference
* easily tapped (low security)

twisted-pair wire disadvantages

coaxial cable

insulated copper wire; used to carry high-speed data traffic and television signals (cable TV); connect the backbone to individual devices on the network;less susceptible to electrical interference, and it can carry much more data than twisted-pair

* higher bandwidth than twisted-pair wire
* less susceptible to electromagnetic interference

coaxial cable advantages

* relatively expensive and inflexible
* easily tapped (low to medium security)
* somewhat difficult to work with

coaxial cable disadvantages

fiber-optic cable

a communication medium consisting of thousands of very thin filaments of glass fibers, surrounded by cladding, that transmit information through pulses of light generated by lasers; significantly smaller and lighter than traditional cable media; typically used as the backbone for a network

* very high bandwidth
* relatively expensive
* difficult to tap (good security)

fiber-optic cable advantages

* difficult to work with
* difficult to splice

fiber-optic cable disadvantages

cladding

a coating that prevents the light from leaking out of the fiber in fiber-optic cables

broadcast media/wireless media

communications channels that use electromagnetic media (the “airwaves”) to transmit data

nodes

computing devices that are connected to the network must access and share the network to transmit and receive data; work together by adhering to protocol

protocol

set of rules and procedures that govern transmission across a network and enable devices to communicate with one another

* ethernet
* transmission control protocol/internet protocol

two major protocols include

ethernet

a common local area network protocol; many use the 100-gigabit through which the network provides data transmission speeds of 100 gigabits (100 billion bits) per second

transmission control protocol/internet protocol (TCP/IP)

a file transfer protocol that can send large files of information across sometimes unreliable networks with the assurance that the data will arrive uncorrupted; protocol of the Internet

* manages the movement of data packets between computers by establishing a connection between computers
* sequences the transfer of packets
* acknowledges the packets that have been transmitted

three basic functions of TCP

internet protocol (IP)

a set of rules responsible for disassembling, delivering, and reassembling the data during the transmission and packets over the Internet

packets

data is divided into small, fixed bundles before it is transmitted over the Internet; each one carries the information that will help it reach its destination (sender’s IP address, recipient’s IP address, etc.); travels independently across the network and can be routed through different paths in the network; reassembled into the original message when it has reached the destination; use the TCP/IP protocol to carry data

packet switching

the transmission technology that divides blocks of text into packets; reliable and fault tolerant; packets can be rerouted around a path if it is busy or broken; used to achieve reliable end-to-end message transmission over sometimes-unreliable networks that may have short-acting or long-acting problems

* application layer
* transport layer
* internet layer
* network interface layer

four layers of the TCP/IP functions

application layer

layer enables client application programs to access the other layers, and it defines the protocols that applications use to exchange data

hypertext transfer/transport protocol (HTTP)

the communications standard used to transfer pages across the WWW portion of the Internet; defines how messages are formulated and transmitted, and how they are interpreted by their receivers

transport layer

layer provides the application layer with communication and packet services; includes TCP and other protocols

internet layer

layer responsible for addressing, routing, and packaging data packets; IP is one of the protocols in this layer

network interface layer

layer that places packets on, and receives them from, the network medium, which can be any networking technology

distributed processing

network architecture that divides processing work between or among two or more computers that are linked together in a network'; process enables computers in different locations to communicate with one another through telecommunications links

client/server computing

form of distributed processing that links two or more computers in an arrangement in which some machines (servers) provide computing services and perform computing functions for end-user PCs (clients)

servers

computers that provide access to various network services, such as printing data, and communications

clients

computers, such as users’ personal computers, that use any of the services provided by servers

fat clients

computers that offer full functionality without having to connect to a network; have large storage and processing power and can run local programs (such as Microsoft Office) if the network goes down

thin clients

computer that does not offer the full functionality of a fat client; may have no local storage and only limited processing power; depend on the network to run applications; so they are of little value when the network is not functioning

peer-to-peer processing (P2P)

type of client/server distributed processing that allows two or more computers to pool their resources, making each computer both a client and a server

1. accessing unused CPU power among networked computers
2. real-time, person-to-person collaboration
3. advanced search and file sharing (characterized by natural language searches of millions of peer systems)

three basic types of peer-to-peer processing

Internet (the Net)

a massive global WAN that connects approximately 1 million organizational computer networks in more than 200 countries on all continents

Internet backbone

primary network connections and telecommunication lines that link the computers and organizational nodes of the Internet; fiber-optic network that is operated primarily by large telecommunications companies

intranet

a private network that uses Internet software and TCP/IP protocols; uses IP so users can take advantage of familiar applications and work habits; support discovery (easy and inexpensive browsing and search), communication, and collaboration inside an organization

extranet

a network that connects parts of the intranets of different organizations; enables business partners to communicate securely over the Internet using virtual private networks (VPNs); offer limited accessibility to the intranets of participating companies, as well as necessary interorganizational communications

internet service provider (ISP)

a company that provides Internet connections for a fee (AT&T, Verizon, etc.); connect to one another through network access points

network access points (NAPs)

computers that act as exchange points for Internet traffic and determine how traffic is routed; key components of the Internet backbone

fiber-to-the-home (FTTH)

connecting fiber-optic cable directly to individual homes

internet protocol (IP) address

an assigned address that uniquely identifies a computer on the Internet; each computer has one to distinguish it from all other computers; consist of a set of numbers, in four parts, separated by dots

* IPv4
* IPv6

two IP addressing schemes

IPv4

most widely used IP addressing scheme; consists of 32 bits (2^32 possibilities for IP addresses)

IPv6

IP addressing scheme consisting of 128 bits; accommodates for the rapidly increasing number of devices needing IP addresses

internet corporation for assigned names and numbers (ICANN)

corporation that coordinates IP addresses throughout the world

domain name system (DNS)

the system administered by the Internet Corporation for Assigned Names and Numbers (ICANN) that assigns names to each site on the Internet

domain names

the name assigned to an Internet site, which consists of multiple parts, separated by dots, that are translated/read from right to left

top-level domain (TLD)

domain at the highest level in the hierarchical Domain Name System of the Internet; located in the root zone (rightmost zone) of the name (.com, .edu, .gov, etc,)

Internet2

a new, faster telecommunications network that deploys advanced network applications; designed to be fast, always on, everywhere, natural, intelligent, easy, and trusted; not a separate physical network from the Internet

world wide web (the web/WWW)

a system of universally accepted standards for storing, retrieving, formatting, and displaying information through a client/server architecture; handles all types of digital information (text, hypermedia, graphics, sounds, etc.)

hypertext

text displayed on a computer display or other electronic devices with references, called *hyperlinks*, to other text that the reader can immediately access, or where text can be revealed progressively at additional levels of details

hyperlink

a connection from a hypertext file or document to another location or file, typically activated by clicking on a highlighted word or image on the screen or by touching the screen

website

collectively, all of the Web pages of a particular company or individual

webmaster

person in charge of an organization’s website

uniform resource locator (URL)

the set of letters that identifies the address of a specific resource on the Web

browsers

software applications through which users primarily access the Web

* discovery
* communication
* collaboration
* education

four network applications

search engine

a computer program that searches for specific information by key words and reports the results; maintains an index of billions of Web pages and uses that index to find pages that match a set of user-specified key words such indexes are created and updated by webcrawlers

webcrawlers

computer programs that browse the Web and create a copy of all visited pages

metasearch engines

a computer program that searches several engines at once and integrates the findings of the various search engines to answer queries posted by users

portal

a Web-based personalized gateway to information and knowledge that provides relevant information from different IT systems and the Internet, using advanced searching and indexing techniques

* commercial
* affinity
* corporate
* industrywide

four types of portals

commercial (public) portal

a website that offers fairly routine content (some in real-time) for broad and diverse audiences; offers customization only at the user interface; most popular type of portal on the Internet

affinity portal

a website that offers a single point of entry to an entire community of affiliated interests, such as a hobby group or political party

corporate portal

website that provides a personalized, single point of access through a Web browser to critical business information located both inside and outside an organization; makes it easier to find needed information and offer customers and employees self-service opportunities

industrywide portal

 Web-based gateway to information and knowledge for an entire industry

electronic chat

an arrangement in which participants exchange conversational messages in real time in a *chat room;* chat programs allow you to send messages to people who are connected to the same channel of communication at the same time you are

internet telephony (voice-over-internet protocol/VoIP)

the use of the Internet as the transmission medium for telephone calls; phone calls are treated as another kind of data; analog voice signals are digitized, sectioned into packets, and then sent over the Internet

unified communications (UC)

common hardware and software platform that simplifies and integrates all forms of communications (voice, e-mail, instant messaging, presence (location) services and videoconferencing) across an organization; presence services enable users to know where their intended recipients are and if they are available, in real time; unifies all forms of human and computer communications into a common user experience; enables users to seamlessly collaborate with another person on a project, regardless of where the user is located

telecommuting

a work arrangement whereby employees work at home, at the customer’s premises, in special workplaces, or while traveling, usually using a computer linked to their place of employment; highly prized workers are able to work anywhere anytime

distributed workers

those who have no permanent office at their companies, preferring to work at home offices, in airport lounges or client conferences rooms, etc.; growth of the distributed workforce is driven by globalization, extremely long commutes to work, widespread broadband communications links (wireline and wireless), and powerful computing devices

* reduced stress and improved family life for employees
* increased productivity, ability to retain skilled employees, and ability to attract employees who do not live within commuting distance for employers

advantages of telecommuting

* increased feelings of isolation, possible loss of fringe benefits, lower pay (in some cases), no workplace visibility, lack of socialization, and the potential for slower promotions
* difficulties in supervising work and potential data security problems for employers

disadvantages of telecommuting

collaboration

mutual efforts by two or more individuals, teams, groups, or organizations who perform activities together to accomplish certain tasks

workgroup

two or more individuals who act together to perform a task, on either a permanent or temporary basis