11A Flashcards
The _____________ is how data travels from one component or device to another. This can be done by cable or by wireless such as RF or light.
physical environment
A LAN using coaxial cable, twisted-pair cable, and/or fiber optic cable is using __________.
guided media
Impairments in guided transmission lines can create __________, which degrades the analog and digital signal quality
distortion
________________ does not use a physical means but relies instead on
radio waves or light transmissions.
Unguided media
_________ cables are the oldest and most used types of transmitting data.
Copper
The copper wire in the cables could be ____________ together to form the individual wire in the cable
solid or stranded twisted
Twisted-Pair Cable is the ____________ media for network connectivity.
most common
Twisted-pair cable consists of…?
solid insulated wires twisted in the cable
The twisted-wire configuration limits signal degradation from…?
electromagnetic interference (EMI) and radio frequency interference (RFI).
Twisted-pair cable has ____________ governing the number of twists or braids permitted per meter.
precise specifications
Twisted-pair is a copper, wire-based cable that can be either ___________.
shielded or unshielded
What does UTP stand for?
Unshielded Twisted Pair
UTP has become the most ___________ choice among networking cables
economical
In most cases, UTP cable is implemented using inexpensive, modular
telephone-type connectors such as the ______ (two pair, common telephone) and the ______ (four pair, data) connectors.
RJ-11 and the RJ-45
UTP contains ______ insulated wires.
eight
In UTP, ________ are twisted together, a precise number of
turns per meter, to form a pair.
two insulated wires
The ANSI specifies categories of UTP in terms of _______ they can sustain.
data rates
Categories describe the media as well as the types of ________ to be used.
connectors
What are the “pin layouts”?
The pin layouts are TIA based standards using the T-586A standard for network cables
What are the three basic configurations for pin layouts?
Straight through, cross over, roll over
Describe straight through pin layout
Pins on end of the cable match. A Straight Through cable is used to connect two unlike devices, such as a PC to a switch.
Describe cross-over pin layout
TX and RX pins are swapped on the opposite end of the cable. A Cross-Over cable is used to connect like devices, such as switch to switch.
Describe roll over pin layout
Pins are exactly opposite on the ends of the cables. The Roll Over cable is commonly referred to as a console cable and is used to connect a PC to the console port of a switch or router.
What does STP stand for?
Shielded Twisted Pair
What is STP?
STP cable combines the techniques of shielding and twisting of wires to protect against signal degradation.
STP contains _____ pairs of wire.
four
Each pair of wire is twisted together a precise number of turns per meter. Each pair is then wrapped, as a pair, in ______________.
insulating metallic foil
After being wrapped in metallic foil, the four insulated pairs are then wrapped together in metallic braid or foil called the _______
jacket
The major benefit of STP is that it reduces…?
reduces electrical noise both within the cable (pair-to-pair
crosstalk) and outside the cable (Electromagnetic Interference and Radio Frequency Interference).
With fiber optics, technology converts electrical signals (ones and zeros [binary] into ___________ (on and off lighting).
optical signals
Optical signals are transmitted through a thin glass fiber. These signals are converted back into ________ at the receiving end.
electrical signals
Because these transmissions are light-based instead of
electrical based, fiber is immune to all types of electromagnetic (EMF) monitoring because…?
There is no EM radiation
What are the two types of fiber optic cable?
Multi-Mode and Single-mode
Multi-mode fiber typically has a core diameter of _________.
This relatively large core allows many modes, or paths, of light to propagate down the optic path producing good coupling from inexpensive couplers, connectors, and LED light sources.
Multi-mode fiber typically has a core diameter of 50 to 100 microns.
Two types of multi-mode fiber exist, which are?
graded and stepped
Multi-mode fiber supports ________ than twisted-pair wire.
longer segment lengths
Multi-mode fiber can support segment lengths as long as ______ meters for 10 and 100 Mbps Ethernet, and _____ meters for 1 Gbps Ethernet.
2000
550
Single mode fiber, shown in Figures 11-5 and 11-6, uses a glass fiber that is approximately _________ in diameter and permits a single mode of light to be propagated using expensive lasers as the light source.
10 microns
________ can support much longer segments than any other guided media.
Single-mode fiber
_________ transmissions are wireless.
Unguided/unbound
_______________ can impair your wireless transmission, degrading both analog and digital signal quality.
Atmospheric conditions
The most used wireless media are…?
light transmissions and radio waves
Light transmissions use ______ to transmit and receive network signals.
lasers
Since laser transmissions use a focused beam of light, they require a _________ and _________ between the devices.
clear line of sight and precise alignment
Radio waves may be land-based or _____-based transmissions.
space-based
Radio transmission signals originate from a land-based system but are transmitted to _____________.
satellites
Radio waves used for networking purposes are typically microwave frequencies in the ____________ range.
1-20 gigahertz (GHz)
Radio wave signals can be ____________ or _____________ in nature.
fixed frequency or spread spectrum
With fixed frequency signals, the information you wish to transmit is superimposed onto a RF carrier, which increases ______ and _______ of the signal.
power and range
Security of fixed frequency signals is poor because…?
once the carrier frequency is known, fixed frequency signals are easy to
monitor and/or jam.
What is an example of a fixed-frequency signal?
a radio station
Spread spectrum signals is a transmission technique that transmits a signal across a broad frequency bandwidth and…?
varies as the RF carrier frequency varies
What are some reasons for using the spread spectrum signals technique?
To secure communications, to increase resistance to natural interference, noise, and jamming
What are the advantages of unguided media?
- Mobility - there is no physical cabling to tie down the location of a node on a network; a portable computer can truly be portable
- Relocatable - Moving a wireless node is easy compared to the large amount of labor required to add or move cabling in a guided or bound type of network.
What are the disadvantages of unguided media?
- Security: Security is poor. Signals are more susceptible to interception and monitoring.
- Distortion and Interference: Susceptible to interference and distortion from lights, electronic devices, and atmospheric conditions.
- Speed: Slower speed than guided media LAN’s
T-568A standard is what color wire?
Green
T-568B standard is what color wire?
Orange
