Term
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Definition
The most commonly used cable type in LAN.
Relatively easy to work with, flexible, efficient, and fast contains eight wires grouped into four twisted pairs, typically blue, orange, green, and brown.
The twisted wires reduce crosstalk and interference. Voir tableau 568B, 568A, and BOGB standards |
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Term
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Definition
Medium dependent interface (MDI)
Type of Ethernet port connection using twisted pair cabling.
For computers to communicate with other devices, the wires have to cross somewhere. Instead of using crossover cables to connect computers to central connecting devices such as switches.
These central connecting devices are equipped with MDI-X ports (medium dependent interface crossover), which take care of the cross.
The tools necessary to make the connections between patch panels and RJ45 jacks include a cutting tool, a wire stripper, a punch down tool, and a testing device known as a continuity tester, which tests all of the pins of a connection one by one. |
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Term
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Definition
The quantity of information reaching the receiver as compared to the transmitted quantity of information.
Measured in decibels (dB)
According to the IEEE 802.3 standard, twisted-pair cables can be run 100 meters. Beyond this the signal degrades to such a point that it cannot be interpreted by the destination host.
A signal repeater, a hub, or switch can be used If a cable needs to be run farther. |
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Term
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Definition
Anything that disrupts or modifies a signal that is traveling along a wire |
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Term
Electromagnetic Interference EMI |
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Definition
An affect electrical circuits, devices, and cables due to electromagnetic conduction and possibly radiation.
Any type of electrical device causes EMI: TVs, air conditioning units, motors, unshielded electrical cables (Romex).
Copper-based cables and network devices should be kept away from these electrical devices and cables to prevent network communication issues. |
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Term
Radio Frequency Interference (RFI) |
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Definition
This is interference that can come from AM/FM transmissions and cell phone towers.
It is often considered part of the EMI family and is sometimes even referred to as EMI.
Filters can be installed on the network to eliminate the signal frequency being broadcast by a radio tower, although this will usually not affect standard wired Ethernet networks. |
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Term
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Definition
When the signal that is transmitted on one copper wire or pair of wires creates an undesired effect on another wire or pair of wires |
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Term
Near end crosstalk (NEXT) |
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Definition
Occurs when there is measured interference between two pairs in a single cable, measured on the cable end nearest the transmitter. |
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Term
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Definition
Occurs when there is similar interference, measured at the cable end farthest from the transmitter. |
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Term
Shielded Twisted-Pair (STP) Cables |
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Definition
STP cables have an aluminum shield inside the plastic jacket that surrounds the pairs of wires. |
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Term
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Definition
Cables installed inside walls or above drop ceilings where they cannot be accessed by sprinkler systems in the case of a fire should be plenumrated or low-smoke rated.
Plenum-rated cables have a Teflon coating that makes them more impervious to fire.
They are used in these situations because standard twisted-pair cables have a PVC jacket, which can emit deadly gas into the air. |
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Term
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Definition
| transmits light (photons) instead of electricity over glass or plastic “fibers” Very good for high-speed, high-capacity data transmission due to lack of attenuation Single-mode meant to carry a single ray of light—one ray of light, one mode This type of cable is normally used for higher-bandwidth, longer-distance runs, generally 10-80 km More expensive equipment Multi-mode Cable with a larger fiber core, capable of carrying multiple rays of light. This type of cable is used for shorter distance runs, up to 600 meters. Though much shorter than single mode fiber runs, this is still six times the distance of twisted-pair cable runs. Less expensive equipment |
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Term
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Definition
Extend connectivity to a pre-existing wireless network and could be used to connect entire local area networks to the Internet.
Some wireless devices can be connected directly to each other in a point-to-point fashion.
Wireless network adapters enable connectivity between a desktop computer or laptop and the wireless access point.
These network adapters come in a variety of shapes and sizes, including USB, PC Card, and as an internal PCI or PCI Express adapter card.
A wireless access point (WAP) enables wireless devices to connect to a wired network.
A wireless router can also acts as a router, firewall, and IP proxy. |
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Term
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Definition
Infrastructure
Used when wireless clients connect to and are authenticated by a wireless access point.
Ad-hoc
Used when all of the clients communicate directly with each other. |
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Term
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Definition
Network composed of at least one WAP and a computer or handheld device that connect to the WAP.
Usually these networks are Ethernet based, but they can be built on other networking architectures.
In order to ensure compatibility, the WAP and other wireless devices must all use the same IEEE 802.11 WLAN standard.
Wireless Fidelity (WiFi ) is a trademark to brand products that belong to the category of WLAN devices.
Voir VLAN Standards. |
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Term
Wireless Encryption Option |
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Definition
WEP
Wired Equivalent privacy
64bit
WPA&WPA2
Wifi protected access
256bit
TKIP
Temporal Key integrity protocol
128bit
AES
Advanced encryption standard
128 - 192 - 256bit |
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Term
Service Set Identifier SSI |
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Definition
When utilizing infrastructure mode, the base unit (normally a WAP) will be configured with a service set identifier (SSID).
The SSID is the name of the wireless network, and it is broadcast over the airwaves.
When clients want to connect to the WAP, they can identify it by the SSID.
For security, the SSID can be hidden from public discovery. |
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