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41 Cards in this Set
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- Back
permit terminal-to-computer and computer-to-computer communications over an analog telephone line. Converts digital data into analog data at the tranmitting end and converts analog data back into digital data at the reciving end |
modems |
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used in a wode area of applications with in the communication wold |
converters
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changes analog signals to a digital (binary) representation. Modems use this to change the carious voltage levels into a binary representation of voltages |
A/D converters |
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change a set of digital binary numbers into a specific voltage proportional to the bin ary value. There purpoes is to convert digital signals into analog signals |
D/A conveters |
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connect various types of cables that exist with in a network |
network media converters |
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acts as a translator between workstations or networks that use different operating systems, communication protocols, data format structures or network hardware architectures by enabling the nodes to communicate with different types of networks or devices |
gateways |
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connects workstations in the main frame network that would otherwise not recognize the workstation. Workstations appear as IBM 3270 (dumb) terminals to the mainframe host |
IBM host gateways |
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translates messages from one vendors messaging appliation to another vendors application |
e-mail gateway |
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devices that filter packets between LAN segments and are used in physical star and tree toplogies. Using these in a network will greatly reduce or eliminate collisions on a network |
switches |
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the entire packets is recieved and placed into the buffer memeory, where an error check is performed and the packet is sent to the proper part for delivery |
store-and-forward |
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does not perform a CRC check or store the entire packet. As soon as the address is recieved into the buffer, the frame is directed to the proper part for delivery with out being checked for errors |
cut-through |
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sometimes referred to as modified cut-through. the switch checks the first 64bytes of a frame for fragmentation before forwarding the frame to the proper part for delivery |
fragmentfree |
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a device that connects two ore more LAN segments to effectively make those segments one logical network. Provide filtering and forwarding services |
bridges |
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operate at the OSI network layer and are used to connect two or more netowork segments or networks |
routers |
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a date from many different types of equipment. encryption is done by hardware devices. the data is encrypted in order to be carried securley over leased lines, satellite, microwaves or radio signals. |
WIde band encryption |
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informations from telephones. encryption is done by hardware devices. the data is encrypted in order to be carried securly over leased lines, satellite, microwaves or radio signals |
narrowband encryption |
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is obtained by combining multiple signals, such as data and/or voice lines, onto one line. Encryption is done by hardware decives. the data is encrypted in order to be carried securley over leased lines, satellite, microwaves or radio signals. |
bulk encryption |
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all types of incription plus the use of software encryption |
network encryption |
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the means or way information travels from one location to another. |
communication mediums |
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the physical environment through which data travels as it moves from one component or device to another. |
guided/bound media |
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wireless. they have no physical constraints confining the signal to a set path. atmospheric conditions can impair your wireless transmissions, degrading both analog and digital signal quality |
unguided/unbound media |
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has a solid center conductor, surronded by an insulating spacer that is surrounding a grounded shield of braided wire, foil or both. the shield minimizes electrical and radio frequency interference. the entire assembly is covered with an insulating and proective outer layer. |
Coaxial cabling |
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COAX cable used in ethernet 10base5 networks. typically a bright color and is marked with black band every 2.5 meters to inicate proper placement of the transceiver called a media access unit (MAU) |
thicknet |
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COAX cable used in ethernet 10base2 networks. this cable is cheaper, lighter, more flexible, and easier to install. |
thinnet |
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most common media for netowork connectivity. limits signal degradation from electromagnetic interference (EMI) and radio frequency interference (RFI). |
Twisted-pair cable |
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this cable combines the techniques of shielding and twisting of wires to protect against signal degradation. contains four pairs of wire. specified for use in ethernet network installations, reduces electrical noise both withing the cable and from outside the cable |
shielded twisted-pair (STP) |
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has become the most economical choice amont networking cables. contains 8 insulated wires. |
unshielded twisted pair (UTP) |
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voice-grade telephone wire. not suitable for data transmission |
category 1 |
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certified for data ransmission up to 4 Mbps |
category 2 |
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certified for data transmission up to 10 Mbps (ethernet standard) |
category 3 |
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rated for data transmission up to 16 Mbps (IBM token ring standard) |
category 4 |
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rated for data transmission up to 100 Mbos (fast thernet standard) |
category 5 |
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rated for data transmission up to 1000 Mbps (gigabit ethernet standard) |
category 6 |
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typically has a core diameter of 50 to 100 microns. this relatively large core allows many modes, or paths, of light to propagate down the optic path producing good coupling from inexpensive couples, connectors, and LED light soources. supports longer segment lengths than a twisted-pair wire. |
multi-mode fiber (MMF) |
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uses a glass fiber that is approximately 10 microns in diameter and permits a single mode of light to be propagated using expensive lasers as the light source |
single-mode fiber (SMF) |
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uses lasers to transmit and receive network signals. provides a relativily secure transmission medium when guided medium cannot be used |
light transmission |
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the information you wish to transmit is superimposed onto an RF carrier, which increases power and range. |
fixed frequency signals |
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the transmit signal frequency varies as the RF carrier frequency varies. this reduces noice interfernece |
spread spectrum signals |
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a communication device that combines several data or voice signals for transmission over one signle medium. primary purpose is to save communications cost. provide error correction and data security. |
multiplexer |
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combines several different data signals onto a single fiber optic cable. |
wave division multiplexing |
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invloves the distirbution of multiple signals in the time domain, a digital process. |
time division multiplexing (TDM) |