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Chaper 3 LANs and WANs

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Understand he basics of a local area network and a wide area network.
A LAN connects computers in a small geographic area, such as an office. A WAN connects compuers and netwrks over a larger area.
Be able to identify Carrier Sense Multiple Access/Collision Detection (CSMA/CD)
All ethernet methods use CSMA/CD to cntrol LAN access, which allows only one computer at a tme to transmit a signal on the network.
Be able to identify the Institute of Electrical and Electronics Engineers (IEEE) 802.2 LAN standard, Ethernet, and CSMA/ CD.
IEEE 802.2 defines the Logical Link Conrol (LLC) and MAC connection standards.
Be able to identify the IEEE 802.3 LAN standard and Ethernet.
IEEE 802.3 uses a MAC address along with Ethernet, in which only one LAN station at a time may broadcast a signal on the network.
Know the differences between logical and physical addesses.
A logical address (IP address) is used to send data between two networks.

A physical address such as a MAC (Media Access Control address) is used to send data between two computers in the same physical link.
Know the Token Ring networking standard.
IEEE 802.5 defines the token ring network, in which a token identifies the destination of the signal.
Understand WAN standards, including X.25, frame relay, and ATM.
X.25: PAcket-level error correcting protocol used for credit card and automated teller machine transactions at speeds of 56Kbs and less.
Frame relay: Fast packet switching tech. that can connect dedicated lines at speeds betw. 64Kbps and 1.544Mbps.
ATM: Transmits data at speeds up to 1.2Gbps using 53 byte cells.
Understand how various LAN/WAN devices work together, including NICs, repeaters, hubs, bridges, routers, brouters, switches, gateways, CSU/DSU, and patch panels.
Every PC must have a NIC to provide a connection.

Repeaters regenerate a network signal to help cover long distances.

Hubs connect several computers within a LAN.

Bridges connect network segments using hardware addresses.

Routers connect networks to each other using IP addresses.

Brouters can connect network segments and networks by using hardware addresses.

Switches connect network noes at a higher speed than hubs, bridges, and routers.

Gateways translate protocols.

CSU/DSU terminates that physical connection of a dedicated circuit such as a T1.

A patch panel helps connect computers and networks at a specific location.
Understand the differences among common transmission media used in networking such as twisted-pair, coaxial, fiber optic cable, and wreless media.
Twisted-pair: Frequently used n office LAN installations. It is available in seven categories.
Coaxial cable: Used for high bandwidth installations n a building.
Fiber-optic lines: Used for very high bandwidth connections.
Wireless media: Implemented as part of a hybrid network with wireless media connecting a workstation to the cabled network.
Know transmisson types, including asynchronous and synchronous, simplex, half-duplex, full duplex, baseband and broadband.
Synchronous: Network lines use syn. trans., with a clock providing the same beat for the origin and destination.
Asynchronous: Dialup modems use asynchonous which uses no clock, but requires the same speed for transmission and reception.
Half-duplex: Data can travel in one direction at a time.
Full-duplex: Data travels in boh directions simultaneously.
Baseband: Uses the entire bandwidth to send one signal.
Broadband: Dedicates a channel or portion of the bandwidth to each signal.
Know the function and types of T-carrier and E-carrier systems.
The T-carrier system is the digital transmission format used n the US< South Korea, and Japan.
The E-carrier system is used in Europe. Each system defines a set of speeds.
Asynchronous
Characterized by the absence of a clock in the transmission media. The access device is not synchronized with the network device. Data is transmitted as individual characters. Each character is synchronized by information contained in the start (header) and stop (trailer) bits.
asynchronous transfer mode
A fast packet switching technology that uses fixed-sized cells and PVCs to support data as well as real-time video and voice. Both LANs and WANs can use ATM, but ATM is most commonly used as an Internet backbone.
BNC connector
A device most commonly used to connect coaxial cable to Network Interface Cards, Hubs, and other network devices. The connector is crimped to the cable using a bayonet mount that connects the two wires (signa and ground) in the coaxial cable to the connector. The connector is then inserted into another connector and trned, which causes the bayonet mechanism tp inch wo pins into the BNCs locking groove. Also called British Naval Connector, Bayonet Neill-Concelman connector.
brouter
A hardware device that combines the functions of a bridge and router, by connecting networks, forwarding outbound packes, and providing other services.
CSMA/CD
The LAN access method used by Ethernet. Checks for network access availability with a signal. After detecting a collision, each computer waits a random delay time and then attempts to retransmit their message.
CSU/DSU
Channel Service Unit/Data (or Digital) Service Unit.
A hardware device that terminates physical connections and is equired when using dedicated circuits, such as T1 lines. Converts digital netwok signals to a format that is suitable for line transmission.
coaxial cable
High-capacity-two-wire (signal and ground) cable;the inner wire is the primary conductor and the metal sheath serves as a ground. Also called coax.
collision
An event that occurs when signals from two computers meet simultaneously on the same network segment.
core
In fiber optic cables, the two strands that send and receive data.
dongle
A hardware cable that connects two devces to each other
Ethernet
A set of hardware technologies and networking protocols for LANs including MAC, and CSMA/CD. Also defined as IEEEE 802.3. First developed at Xerox PARC in 1972.
fast packet switching
A transmission method for mesh-type switching networks where the network does not perform packet sequencing and acknowledgments. See also frame elay and asynchronous transfer mode.
FDDI Fiber Distributed Data Interface
A high-speed LAN standard that uses two counter-rotating rings to provide redundancy and allow the network to function if one ring fails. See also municipal area network.
fiber optic cable
A type of transmission media that uses light to transmit sgnals. It consists of a core wrapped in glass or plasic claddng. Each core and cladding elemen s wrapped with a plastic renforced wuth Kevlar fibers.
frequency division multiplexing (FDM)
The transmission of multiple signals over a single transmission pathm where each signal is within a unique frequency ange carrier. Used in broadband transmissions.
frame relay
A streamlined version of X.25, that uses variable-length packets and allows high-speed connections using shaed network facilities and PVCs (Permanent Virtual Circuits).
gateway
A device that converts sgnals from one protocol sack to another. Also called a protocol converter.
hub
A hardware device that connects computers in a star-configured network so they can exchange information. Most hubs are active hubs; they have a powered supply and can act as repeaters. Also called a concentrator.
IEEE (Institute of Electrical and Electronics Engineers)
An organization of scientists and engineers, accredited by the ANSI (American National Standards Institute)that creates standards for computers and communications.
local area network (LAN)
A group of computers connected within a confined geogaphic aea so that their users can share files and services.
MAC (Media Access Control) address
A unique hardware address that is assigned and burned by the NIC manufacturer, and can be sed to identify a specific computer on a network.
Media Access Control
ALong with Logical Link Conrol one of two sublayers of the IEEE 802.2 standard. Provdes access to LAN media by placing data on he network and provides a physical address or Ethernet address.
multimode fiber optic cable
Uses a large number of frequencies or modes for transmission. The cable's core is larger than that f single-mode. Usually specified for LANs and WANs.
multistation access unit
The network device that is the central connection point for token ring networks.
network interface card (also known as network adapter card)
A hardware device installed in a computer that serves as the interface beween a computer and a network. When using a cable modem, an additional cable cnnects a computer's NIC to the modem. Also called a network adapter card.
patch cord
A cable used to cross-connect networked computers that are wired to the patch panel.
patch panel
A centralized location of sockets representing various network devices so that these devices can be cross-connected as desied, such as connecting a woksation to a hub/switch.
repeater
A device that amplifies the electronic sgnal traveling on a cable segment. It ensues that electronic sgnals do not degrade. A repeater can connect computers that are farther apart than the defined network standards.
router
A network device that determines the best path across a network for data.
shielded twsted-pair (STP) cable
Twisted-pair copper wire that is processed from external electromagnetic interference by a metal sheath wrapped around the wires.
single mode fiber optic cable
A type of cable that uses a specific light wavelength for transmission, the core diameter of which is 8 to 10 microns. Often used for intercity telephone trunks and video applications.
stranded cable
A type of cable that is composed of multiple strands of wire. It's flexible and easy to handle around corners and objects, but has more attenuation o signal loss than solid cable.
switch
A hardware devce hat drects the flow of information from one node to another. There are several varieties of swiches that work at different layes of he OSI/RM.
synchronous
Condition in which data is exchanged in character streams called message-framed data. The access dvce, such as a NIC, and a nework devce, such as a router, share a clock signal and a transmission rate, and a start-and stop sequence is associated with each transmission.
T1
A North American digital carrier standard for snchronous data transmission at a speed of 1.544Mbps.
T3
A North American digital carrier standard for synchronous daa transmission at a speed of 44.736Mbps.
Thicknet
A kind of coaxial cable used for Ethernet networks, such as 10base5 cable.
Thinnet
A kind of coaxial cable used for Ethernet networks, such as 10base2, that is more flexible and smaller than thicknet.
time division multiplexing (TDM)
A method that sends multiple signals over one transmission path by interweaving the signals.
token passing
The LAN access method used by the token ring networks. A data frame or token is passed from one node to the next around the network ring. The node accepts the packet or places it back on the network ring.
token ring
A collisionless network type that uses token passin. One or more tokens can cicle the ring. Originally developed by IBM, and then defined as IEEE 802.5.
transceiver
A hardware device that can transmit and receive data.
twisted pair
A type of cable that uses a twisted pair of wires such as Category 5 cable.
unshielded-twisted-pair cable (UTP)
A type of wised-pair cable that has no radio frequency insulation or shielding.
WAN (wide area networks)
A group of computers connected over an expansve geographic area,, such as a state or country. The internet is a WAN.
X.25
A WAN communications standard that ensures error-free data delivery by checking errors at many points along the data's path. Used for connecting automated teller machines, credit card transaction terminals, and point-of-sale terminals.
The Internet is best described as which of the following?
A. A wide area network.
B. A local area network.
C. An e-mail network.
D. A commercial network.
A wide area network.
A NIC does not require which one of the following items to connect a computer to the Internet?
A. Media
B. Transceiver
C. Device Driver
D. Cable Modem
The first three choices are required. A digital or analog modem is not always necessary for Internet connectivity.
John has a computer on his LAN that is 300 meters away from the server. Which of the following hadware devices wold help him connect these two computers?
A. Bridge
B. Router
C. Switch
D. Repeater
D Repeater. John will want to use a repeater which amplifies a network signal so that it can be sen down an additional length of cable, beyond the point where a signal would start to degrade.
A hub is most commonly associated with which of the following network topologies?
A. Ring
B. Star
C. Peer-to-peer
D. Hybrid
Star network (B)
Rachel needs to connect two token ring networks to each other. The networks are in the same floor of her office buildings. Which hardware device is best suited to this task?
A. Switch
B. Router
C. Bridge
D. Hub
C. Bridge. Rachel should use a bride to connect these two networks to each other. A switch is used for high-speed networks. A router connects networks using their software addresses, which is not appropriate for a token rng network. A hub is used to connect computes in a single network.
Which one of the following devices translates a signal from one networking protocol to another?
A. Switch
B. Hub
C. Gateway
D. Router
A gateway performs his ask. The other devices provide connections. A switch connects two high speed networks. A hub connects computers wihin a netwrk. A router sends signals from one network to another.
How many twisted-pairs of wire are in a category 5 cable?
A. Two
B. Three
C. Four
D. Five
There are four twisted-pair in categories 2 through 7.
A British Naval Connector is usually seen on which of the following cable types?
A. Category 1 cable
B. Coaxial cable
C. Category 5 cable
D. Fiber Optic lines
B
A nomal Ethernet installation can always use which one of the following transmission flows?
A. Full-duplex
B. Half-duplex
C. Simplex
D. Bus
B. Ethernets can always use half-duplex.
A token ring network uses which one of the following transmission methods.
A. Baseband
B. Full-duplex
C. Simplex
D. Broadband
A. Baseband transmission
Which of he following best describes a Media Access Control address?
A. A number assgned to a computer by a server.
B. A number permanently assigned to a NIC.
C. A number assigned to a network by an ISP.
D. A number assigned to a user
B. A MAC address is burned into a NIC cad. It is a physical address for that particular piece of hardware. The other addresses are logical addresses that can be changed and reassigned.
In the IEEE 802.3 specifications, how does a computer send a signal on the LAN?
The computer waits for an idle period to send a signal to all the other computers.
A Fiber Distributed Data Interface uses which of the following?
A. One ring wh very fast cable.
B. One ring with fiber optic lines.
C. Two rings running in opposite directions.
D. Two rings running in the same direction.
C. Two rings running in opposite directions. This provided redundancy. One line can take over a network if the second line fails.
Which of the following choices best descibes frame relay service?
A. Provides fixed cell service at speeds of 1.544Mbps or greater.
B. Provides dedicated connections at speeds of 1.544Mbps or less.
C. Provides fixed cell service at speeds
B. Frame relay provides a dedicated line at speeds between 64Kbps and 1.544Mbps. Frame relay does not use fixed cell lengths. These are used in asynchronous transfer mode.
A T3 carrier can handle all but which of the following data transfer speeds?
A. 64Kbps
B. 800Kbps
C. 1.5Mbps
D. 50Mbps
D. The maximum data transfer rate for a T3 carrier is 44.736Mbps.
The E-carrier system defines daa transfer speeds based on he following multiple?
A. 64Kbps
B. 1.544Mbps
C. 2.048Mbps
D. 56Kbps
C. Explanation: The E-carier system uses 2.048Mbps as its multiple. This speed identifies an E1 carrier.
Which item is required to connect a cable modem to a personal computer?
A. Phone cable
B. Network interface card
C. Router
D. Hub
B. Network Interface card. Routers and hubs are networking hardware. Phone cables are used to connect PCs to phone lines.

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