DS 4250 (Chp 1-4) Exam 1

pervasive networking

one day communication networks will one day be everywhere and virtually and device will be able to communicate with any other device

2 tier architecture

one set of clients and one set of servers

simplex transmission

one way transmission (ex: tv or radio)

circuit

pathway through which messages travel

3) Network Layer

performs routing, determines next computer message should be sent to

PC

personal computer

pbps

peta bits per second, 1000 tbps

Hardware layers

physical & data link layers

HTTP

protocol for communication between web browser and web server

broadband communication

refers to specific type of data transmission that is used by a circuit (ex DSL)

5) Session Layer

responsible for managing and structuring ALL sessions; this includes logging into circuit equipment, transferring files, and performing security checks. Provides an orderly way to end a session or ability to recover from an interrupted sessions

statistical time division multiplexing

selection of transmission speeds is based on analysis of usage requirements of the multiplexed circuits

host-based architecture

server performs virtually all work

protocol

set of rules to help define what the layer will do

time division multiplexing

share communication circuit vertically allowing two or more computer to take turns; time is allocated on the circuit even if data not being transmitted. No guard bands required

middleware

software that sits between application software on the client and application software on the server by translating a client tool into a form understood by a server tool

WAN

span 100 to 1000 miles

BONDING

splits outgoing messages from one client or host across several low speed telephone line and combines incoming message from several lines into one circuit so that it "thinks" it has a faster circuit

server

stores data

radio transmission

synonymous with the word wireless

MIME

takes non text file (ex: graphic) and translates each byte into a text form that SMTP understands and can later be translated by the receivers email client to its original format

2) Data Link Layer

transforms bits marks where a message starts and ends. deals with message delineation, error control (shield other layers from duplicate messages) and network medium access control (MAC addressing works on frame level)

modem

translates analog data to digital data

logical circuit

transmission characteristics (ex: T1 connection)

telecommunications

transmission of voice and video as well as data usually over longer distances

full-duplex transmisson

transmit both ways simultaneously with no turnaround time

1) Physical Layer

transmit data bits (0's and 1's) and rules by which these bits are transmitted, includes all hardware devices (computer, modems, switches) and physical media (cables)

fiber-optic cable

transmits signals via laser inside hair-thin strands

Internetwork layers

transport & network layers

half-duplex transmission

two way transmission; can only transmit one direction at a time

URL

uniform resource locator

guardbands

unused portions of circuit that separate frequencies from each other

VOIP

use your network connection to make phone calls or receive them (Skype, Vonage)

wavelength division multiplexing

uses lasers to transmit different frequencies of light through a fiber optic cable

cloud computing

using applications installed on a server instead of installing them onto physical machines

mainframe

very large general purpose computer capable performing crazy number simultaneous functions and huge data storage

application architecture

way in which the functions of application layer software are spread among clients and servers in the network

client-server architectures

work shared between client and server, DOMINANT

digital

0's and 1's

Functions of Application

1) Data Storage 2) Data Access Logic - SQL (how access data) 3) Application Logic - 4) Presentation Logic - how data looks to user & acceptance user cmds

de juro standardization process

1) specification - developed nomenclature and issues 2) identification - look at solutions and choose best one 3 acceptance - define solution and get industry leaders to agree on one

net neutrality

means that for a given type of content (e.g., email, web, video, music), all content providers are treated the same. For example, all videos on the Internet would be transmitted at the same speed, regardless of whether they came from YouTube, Hulu, or CNN.

server virtualization

means to install many virtual or logical servers on a single physical computer (VMware)

guided media

message flows through physical media such as twisted pair wire, coaxial cable, or fiber optic cable

wireless media

message is broadcast through the air via microwave, satellite, etc

MAN

metrapolitan; spans 3 to 30 miles

n-tier architecture

more scalable and better balance of workload on each server

Internet Model

most commonly used model

data communications

movement of computer information from one point to another by electrical or optical transmission systems

peer to peer networks

networked computers which treat each other as equals and don't rely on a central server to store data

OSI Model

not as common as Internet Model, but required for newtork certification positions; 7 Layers = Please Don't Throw Sausage Pizza Away

monopoly

one business or market is dominating and has complete control over a certain niche (AT&T, RBOC's)

intranet

LAN that uses same technologies as the Internet (html, kava) and only available to those inside an organization

Telnet

enables users to log into servers (ex: PuTTY)

7) Application Layer

end user's access to the network. set of utilities for application programs

green computing

environmentally sustainable computing, less computers needed so less electricity used

DSL

family of techniques that combine analog transmission and FDM to provide voice and data circuits

6) Presentation Layer

formats data for presentation to the user; concerned with displaying and formatting

cluster

group of computers linked together to act as one, work distributed amungst cluster

Federal Communications Commission (FCC)

had the authority to regulate interstate telephone businesses in the United States

coaxial cable

has copper core with an outer cylndrical shell for insulation; cost three times as much as twisted pair wire so dissapearing

symbol rate

how many symbols sent over circuit per second

client-server computing

information system applications divided among network of computers

client

input-output hardware device at users end of communication

information lag

instant data and communication of information between people worldwide no matter where they are

twisted pair cable

insulated pairs of wires that can be packed close together. twisted to minimize electromagnetic interference between wires

BN

a large central network that connects everything else; spans hundreds of feet to miles

scalability

ability to increase or decrease capacity of servers to meet changing needs

extranet

accessible by invited users outside of an organization who access it through the Internet (for example only students enrolled in course can view certain course materials)

physical circuit

actual wire

Protocol Data Unit (PDU)

added to a message as it passes through the layers. often called a packet

multipoint circuit

aka shared circuit many computers connected on the same circuit; only 1 computer can send and receive data at a time however

IMAP

all email stored on the server until it is deleted

thick-client

all or almost all application logic on client

virtual server

allows several OS's be installed on physical computer, eliminates need to purchase separate physical computers

thin-client

little or no application logic placed on client; easier to manage since if app changes only need to update server with application logic

Internet service provider (ISP)

also called telephone companies or other telecommunication providers, provides services such as Internet access, Internet transit, domain name registration and hosting, dial-up access, leased line access and colocation.

turnaround time

amount of time it takes to switch between sending & receiving

codec

analog data to digital data for transmission over digital computer circuits

Internet

both an information system and a communication system. It was started by the U.S. Department of Defense in 1969 as a network of four computers called ARPANET. Its goal was to link a set of computers operated by several universities doing military research. world-wide network of networks

multiplexing

break one high speed physical communication circuit into several lower speed logical circuits so many devices can use while still "thinking" they have their own separate circuits

4) Transport Layer

breaks large data transmission into smaller packets (if needed) ensuring that all packets are received and eliminating duplicate packets. Flow control - make sure computer is not overwhelmed by # message received

client-based architecture

client computers perform most work

3 tier architecture

client, application logic, and database server

inverse multiplexing

combines several low speed circuits to make them appear as one high speed circuit to the user

network computer

communicates using internetbased standards (http, java) but no hard disk

Information Utilities

company that provides wide range of standardized information services

peer-to-peer

computers are both clients and servers; thus share equal work

router

connects 2 or more networks; enables users on one network to communicate with those on another network

LAN

covers clearly defined area such as one floor or work area, single building, group of buildings

American Telephone and Telegraph Company (AT&T)

de facto standardization; One vendor dominating market causing all others to adopt; long-distance telephone services

transaction terminal

designed support business transactions, (ex: ATM)

de juro standard

developed officially (http, html, 802.11n wireless)

Application Service Providers (ASP's)

develops certain system (airline reservation system, payroll system) and companies purchase this system instead of making their own

terminal

device with monitor + keyboard but no CPU

frequency division multiplexing

dividing a circuit horizontally so many signals can travel a single communication circuit simultaneously; use of channels (each transmitting on a different frequency) which don't interfere with each other because they are seperated

analog

electrical signals shaped like sound waves

POP

email must be downloaded to computer and deleted from server before reading

SMTP

email standard on the internet, used to transfer messages that are text

de facto standard

emerge into marketplace and are supported by several vendors but have no official standing (Microsoft word, Windows)