Term
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Definition
| a set of independent computer systems connected by telecommunication links for the purpose of sharing info and resources |
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Term
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Definition
| the individual computers on the network |
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Term
| switched, dial up telephone lines |
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Definition
-in early days of networking this was the most common way to transmit data
-when you dial a telephone number, a circuit is temporarily established between the caller and callee |
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Term
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Definition
| a path that connects the caller to the callee and lasts for the duration of the phone call then is terminated when you hang up |
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Term
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Definition
| the physical quantity used to represent info is continuous and can take on any value (human voice in phone calls) |
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Term
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Definition
| info produced by a computer, a sequence of 0s and 1s |
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Term
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Definition
-modulates or alters a carrier so that it encodes binary info and also performs the inverse operation at the other end of the transmission line
-contraction of modulation and demodulation |
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Term
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Definition
| -at the other end of the transmission line it takes the received waveform, separates the carrier from the encoded digital signal and passes the digital data on the computer |
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Term
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Definition
| -modifies the physical characteristics of the carrier wave, such as frequency and amplitude, so that it is in a state representing 0 or 1 |
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Definition
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Definition
-high error rate and low capacity of a switched telephone line making analog encoding and decoding a slower process
-capacity of information |
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Term
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Definition
-technology that has been rapidly replacing modems and analog phone lines for data communications to and from our homes, schools, and offices
-any communication link with a transmission rate exceeding 256,000 bps
-two widely used options: digital subscriber line (DSL) and cable modem |
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Term
| digital subscriber line (DSL) |
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Definition
-uses the same wires that carry regular telephone signals into your home and therefore is provided by either your local telephone company or someone certified to act as their intermediary
-uses different set of frequencies and it transmits digital rather than analog signals so being on the phone does not interfere with the internet connection
-always on, doesn't require dialing and waiting for the circuit to be established |
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Term
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Definition
| digital subscriber does not have the same transmission speed in the download direction (network to computer) as in the upload direction (computer to network) |
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Term
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Definition
-technology that makes use of the links that deliver cable TV signals into your home, so it is offered by cable TV providers
-always on link, no waiting for dial up |
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Term
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Definition
-most widely used broadband technology in commercial and office environment
-originally designed to operate at 10 Mbps using coaxial cable until the fast version was created |
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Definition
-new and improved version
-transmits at 100 Mbps across coaxial cable, fiber-optic cable, or regular twisted-pair copper wire |
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Term
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Definition
| transmission lines that support speeds in excess of 1 billion bits per second (Gbps) |
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Term
| gigabit ethernet standard |
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Definition
-adopted by IEEE
-supports communication on an ethernet cable at 1,000 Mbps (1 Gbps), 100 times faster than the original 10 Mbps standard |
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Term
| ten-gigabit ethernet standard |
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Definition
-a version of ethernet with the almost unimaginable data rate of 10 billion bits per second
-in a single second a 10 Gbps ethernet network could transmit the entire contents of 1,700 books each 300 pages long |
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Definition
-uses radio, microwave, and infrared signals
-users no longer need to be physically connected to a wired network to access data |
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Term
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Definition
| ability to deliver data to users regardless of their location |
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Term
| wireless local access network |
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Definition
-form of a wireless data connection
-user transmits from his or her computer to a local wireless base station/wireless router that is no more than a few hundred feet away
-typically found in a home, library, office, or coffee shop because its cheap simple low powered and easy to install |
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Term
| base station/wireless router |
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Definition
-no more than a few hundred feet away from the user
-connected to a traditional wired network such as a DSL or cable modem to provide full internet access |
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Term
| Wi-Fi (wireless fidelity) |
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Definition
-official name is IEEE 802.11 wireless network standards
-used to connect a computer to the internet when it is within range of a wireless base station
-often advertised in stores and shops as a hot spot (a router) |
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Term
| IEEE (institute of electrical and electronics engineers) |
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Definition
| an international professional society responsible for developing industrial standards in the area of telecommunications |
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Term
| metropolitan wireless local access network |
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Definition
-wi-fi routers installed every few blocks throughout a city, often on top of phone poles or roofs
-provide convenient low cost wireless internet access to all residents |
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Term
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Definition
-low power wireless standard used to communicate between devices located quite close to each other (30-50 feet)
-often used to support communication between wireless computer peripherals, such as printers, mice, and keyboards
-supports info exchanges between mobile phones, cameras, and video game consoles |
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Term
| wireless wide-area access network |
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Definition
-network that transmits messages from a PDA or smart phone to a remote base station provided by a telecommunications company, which may be located many miles away
-base station is usually a large cellular antenna on top of a tower or building, providing long distance voice and data communication services to any system within sight of the tower |
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Term
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Definition
-popular wireless wide-area access network
-offers voice services as well as data communication at rates of .5 to 2.4 Mbps, comparable to DSL or cable modem |
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Term
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Definition
-connects hardware devices such as computers, printers, and storage devices that are all in close proximity
-owners of computers are also owners of the means of communications |
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Term
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Definition
-all nodes are connected to a single shared communication line
-if 2 or more nodes use the link at the same time, the nodes must take turns using the line to avoid colliding and being unreadable |
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Term
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Definition
| -connects the network nodes in a circular fashion, with messages circulating around the ring in either a clockwise or counterclockwise direction until they reach their destination |
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Term
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Definition
| has a single central node that is connected to all other sites and can route info directly to any other node in the LAN. Messages are first sent to the central site, which then forwards them to the correct location |
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Term
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Definition
-method to construct an ethernet LAN
-a wire strung around and through a building, users tap into the cable at its nearest point using a transceiver |
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Term
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Definition
| device used to help users tap into a shared cable for a LAN |
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Term
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Definition
-a device that simply amplifies and forwards a signal
-can connect 2 LANs so they function as if they were a single network
-limited distances |
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Term
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Definition
| a smarter device that has knowledge about the nodes located on each separate network and examines every message to see if it should be forwarded from one network to another |
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Term
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Definition
-method to constructing an ethernet LAN
-a box, located in a wiring closet, that contains a number of ports with a wire leading from each port to an ethernet interface in the wall, or to a wireless router
-activate by flipping a switch and plugging the machine into the wall socket, or use wi-fi to transmit from computer to wireless router that would connect to one of the ports in the hub
-shared cable is located inside of this instead of in the building walls, so no need to look for the cable |
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Term
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Definition
-connects devices that are not in close proximity but rather are across town, across the country, or across the ocean
-users must purchase telecommunication services
-collection of routers with point to point connections
-each router receives packets and decided where they go and forwards them appropriately |
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Term
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Definition
| directly connect two machines and not the shared channels found on a LAN such as ethernet |
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Term
| store-and-forward, packet switched |
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Definition
-used by WANs to deliver messages
-WAN message must hop from one node to another to make its way from source to destination, not on a shared channel so all nodes receive it |
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Term
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Definition
| an info block with a fixed maximum size that is transmitted through the network as a single unit |
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Term
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Definition
-device that interconnects individual networks
-can transmit info between two distinct networks that use different communication techniques |
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Term
| Internet Service Provider (ISP) |
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Definition
-connects a user's individual computer or a company's private network to the world
-a business whose purpose is to provide access from a private network or an individuals computer to the internet -hierarchical, interconnecting to each other in multiple layers, or triers that provide expanding geographic coverage |
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Term
| tier-1 network/internet backbone |
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Definition
-international ISP
-provides the global coverage |
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Term
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Definition
| -not a single computer network, instead a huge interconnected network of networks that include nodes, LANs, WANs, bridges, routers, and multiple levels of ISPs |
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Term
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Definition
| a mutually agreed upon set of rules, conventions and agreements for the efficient and orderly exchange of info |
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Term
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Definition
-operates the internet
-a nonprofit, nongovernmental, professional society composed of more than 100 worldwide organizations in 180 countries untied by the common goal of maintaining the viability and health of the internet |
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Term
| protocol hierarchy / protocol stack / TCP/IP |
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Definition
| -5 layers: physical, data link, network, transport, and application |
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Term
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Definition
-govern the exchange of binary digits across a physical communication channel
-goal is to create a bit pipe between two computers, such that bits put into the pipe at one end can be read and understood by the computer located at the other end |
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Term
| error detection and correction problem |
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Definition
| -problem when the bits that come out may not be the exact copy of the bits that went in |
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Term
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Definition
| identifying the start and the end of a message, figuring out which bits in the incoming stream belong together |
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Term
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Definition
-address and solve error handling and framing
-done in 2 stages called layer 2a, medium access control, and layer 2b, logical link control |
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Term
| medium access control protocols |
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Definition
-layer 2a in data link protocols
-determine how the arbitrate ownership of a shared line when multiple nodes want to send messages at the same time
-centralized manner: creating a single master control node that determines who gets ownership of the line at any instant in time, rarely used
-contention-based: no central authority, all nodes compete equally for ownership of the line, most used |
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Term
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Definition
-two users monitor a line that is in use, as soon as the line is idle, they transmit at the same time
-all info is lost, the colliding nodes stop sending and wait a random amount of time and then attempt to resend since the random time period is unlikely to be the same |
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Term
| logical link control protocols |
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Definition
-layer 2b in date link protocols
-ensure that the message traveling across the channel from source to destination arrives correctly |
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Term
| ARQ (automatic repeat request) algorithm |
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Definition
| the basis for all data link control protocols in current use |
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Term
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Definition
-nodes A and B are directly connected by a physical link. When A wishes to send a message to B it first adds some additional info to form this
-sequence of numbers uniquely identify this and it adds some error-checking bits that allow B to determine if it was corrupted during transmission
-finally it adds a delimiter to allow node B to know where it begins and ends |
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Term
| acknowledgement message (ACK) |
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Definition
| -special message sent by node B back to node A, containing the sequence number of the correctly received packet so A knows to discard its local copy |
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Term
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Definition
-3rd layer of the protocol stack
-delivers a message from the site where is was created to its ultimate destination
-two responsibilities: create a universal addressing scheme for all network nodes and deliver messages b/w any 2 nodes in the network |
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Term
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Definition
| the network layer of the internet |
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Term
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Definition
-not the names that nodes use to identify each other in IP
-EX: uiowa.edu |
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Term
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Definition
-what nodes use to identify each other
-32-bit often written as 4 8-bit numeric quantities in the range 0-255, each grouping separated by a dot |
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Term
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Definition
-special internet application the converts from a symbolic host name such as uiowa.edu to its 32-bit IP address
-massive database, distributed over thousands of machines that contain the host name-to-IP address mappings for the millions of host computers to the internet |
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Term
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Definition
| a computer that checks to see if it has a data record containing the IP address for a certain symbolic name |
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Term
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Definition
| the process of selecting one specific path |
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Term
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Definition
| highly complex because of the massive volume of data that must be maintained and the enormous amount of processing required to determine the shortest path |
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Term
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Definition
| the optimal route not necessarily in length but in speed, however the message can get from one node to the other the fastest |
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Term
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Definition
| program identifier, usually just a small integer value that serves the same role as the address line |
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Term
| transport layer protocols |
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Definition
-assigning port numbers to programs and remembering which program goes with which port
-create a program-to-program delivery service in which we move messages from a specific program at the source to a specific program at the destination
-examines the newly arrived message to determine which program should get it, based on the port number field inside the message |
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Term
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Definition
-all important applications on the internet use these
-fixed integers that are assigned to certain applications and made known to every machine on the internet |
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Term
| TCP (transport control protocol) |
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Definition
-primary transport protocol
-requires that the 2 programs at the source and destination node initially establish a connection
-does function like an error free channel |
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Term
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Definition
| 2 programs must first inform each other of the impending message exchange and they must describe the quality of service they wish to receive, not a hardware wire |
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Term
| application layer protocols |
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Definition
| -the rules for implementing the end user services provided by a network and they are built on top of the 4 other protocol layers |
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Term
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Definition
| exciting new applications |
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Term
| Uniform Resource Locator (URL) |
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Definition
| symbolic string used to identify a single web page |
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Term
| hypertext transfer protocol (HTTP) |
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Definition
| way to access the hypertext contained in a web page |
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Term
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Definition
| sent on the TCP connection from the client to the server specifying the name of the web page |
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Term
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Definition
-returned from the server to the client along the same TCP connection
-contains a status code specifying whether or not the request was successful and if it was it includes the requested page |
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Term
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Definition
-most popular application of networks for the last 30 years
-it is convenient, supports multimedia, and is a broadcast medium |
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Term
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Definition
| a shared public file where anyone can post messages and everyone is free to read the postings of others |
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Term
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Definition
| specialized bulletin boards that create a community of individuals who share a common interest and want to exchange ideas and opinions |
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Term
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Definition
-the real-time exchange of messages, some news groups support them
-appear on peoples screens immediately |
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Term
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Definition
-rapid exchange of messages often using wireless technology
-another form of real-time message exchange
-provided by MSN yahoo and AOL |
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Term
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Definition
| systems that create communities of users who share common interests and activities and which provide multiple methods of online interaction |
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Term
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Definition
| the ability to share physical resources such as a printer or storage device as well as logical resources such as software and info |
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Term
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Definition
| -a few shared printers that can be accessed whenever needed |
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Term
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Definition
| a shared network disk that holds a single copy of data and software for users, also a cost effective way to provide shared backup services to multiple sites |
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Term
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Definition
| the style of computing wherein some nodes provide services while the remaining nodes are users/clients of those servers |
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Term
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Definition
| a service made so the network can access scientific, medical, legal, and commercial data files stored on systems all over the world |
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Term
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Definition
| shares info among the geographically dispersed sites of a multinational corporation, can be accessed by authorized users regardless of location |
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Term
| information utility/data warehouse |
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Definition
| contain massive amounts of info that can be electronically searched for specific facts or documents |
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Term
| collaborative software/groupware |
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Definition
| software that facilitates the efforts of individuals connected by a network and working a single shared project |
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Term
| electronic commerce (e-commerce) |
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Definition
| a general term applied to any use of computers and networking to support the paperless exchange of goods, info, and services in the commercial sector |
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Term
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Definition
| stated that any WAN is free to do whatever it wants internally however at the point where two networks meet, both must use a common addressing scheme and identical protocols (they must speak the same language) |
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Term
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Definition
| makes the internetwork connections and provides routing between different WANs |
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Term
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Definition
| a software package that allows users to log on remotely to another computer and use it as though it were their own local device |
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Term
| FTP (file transfer protocol) |
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Definition
| provides a way to move files around the network quickly and easily |
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Term
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Definition
-national network built by NSF to interconnect six NSF supercomputer centers with dozens of new regional networks set up by NSF
-used TCP/IP technology identical to the ARPANET |
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Term
| internet service providers |
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Definition
| offered the internet access once provided by ARPANET and NSFNET after the exit of the US gov from the networking arena |
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Term
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Definition
| a collection of documents interconnected by pointers called links |
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Definition
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Term
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Definition
| pointers that let users move freely from page to page |
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Term
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Definition
-information system made by Berners-Lee made available to all researchers in 1991, then in 1993 to everyone without fees or royalties
-browsers began appearing (mosaic, netscape, internet explorer, etc) |
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