MISC 372 Ch.5
Fiber that has a core diameter of 8 microns in
...
In this book, we use the terms "Ethernet" and "802.3" interchangeably
...
Light aggregation can increase trunk speed by a factor of
...
The ethernet length field gives the length of the
...
The longest transmission distances are possible with
...
The main benefit of parallel transmission over serial transmission is
...
What 802 Working Group creates Ethernet standards
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Which light wavelength dominates in LANs
...
CAT 5e and CAT 6 wiring can carry Ethernet 100 meters up to
1 Gbps
What type of copper wiring is widely used in Ethernet?
4-pair UTP
How many wires are there in a UTP Ethernet cord
8
Which working group is likely to develop security standards to be used by multiple LAN/WAN technologies
802.1
ARP cache poisoning can be defeated using ________.
802.1AE
The ________ standard was created to prevent attackers from walking in and simply plugging a computer into a wall jack and therefore accessing the network
802.1X
In digital signaling there is (are) ___ state(s)
A small number of
Which UTP quality levels can send signals at 10Gbps
Both Category 6 and Category 6A
The Ethernet data field contains
Both a packet and the LLC subheader
Which UTP quality levels can send signals at 10Gbps for 100 meters
Category 6A
The official name for Ethernet addresses is the ___ addresses
EUI-48
UTP
Ethernet LANS typically use this wiring to connect users to the nearest switch, at two ends wires are placed within an RJ-45 connector
What organization creates Ethernet standards?
IEEE
multimode fiber
LANs use this, which is relatively thick core, light rays can enter over a wide range of angles, quality is measured by modal bandwidth in MHZ.km
Ethernet's hierarchical topology tends to create
Lower cost per frame handled
Ethernet addresses were formerly called
MAC
Ethernet has only a single standard at the ___ layer
MAC
Which of the following is used most heavily in LANs for fiber transmission links
Multimode fiber
Ethernet's hierarchical topology makes it ________
Neither expensive nor reliable. CHEAP
sadipscing elitr, sed diam
None of these
What is the maximum power for POE Plus in the standard?
Not "75 watts"
Which of the following is a benefit of using a central authentication server?
Not "consistency in authentication"
Strong security is needed to
Not "reduce total cost"
Link aggregation can increase trunk speed by a factor of ________.
Not "two" not "neither two nor three"
___ fiber is being sold today
OM4
4-pair UTP terminates in a(n) ___ connector
RJ-45
In LANs, ___ typically is for ___
UTP, access lines
Ethernet can offer ___ priority levels
Up to 8
Frequency, wavelength, and amplitude.
What are the three characteristics of light waves?
signal
a disturbance that propagates down a transmission medium to the receiver, which reads the signals
modal dispersion
a limiting factor for distance in multimode fiber
category (cat)
a measure of UTP quality
An Ethernet switch knows
a single port number for each EUI-48 address
local loop
access link between the customer premises and the nearest telephone company switch (called the end office switch)
noise spikes
always cause some errors and cause more errors as the SNR decreases and the Number of errors become unacceptable well before the signal reaches the noise floor
single-mode fiber
are used by carrier and limited by absorptive attenuation; carry signals much farther than multimode fiber
full‐duplex transmission
attenuationThe ability to transmit in both directions simultaneously for optical fiber cord
In 802.1X, the workgroup switch is the ________.
authenticator
Which of the following is relatively immune to small errors
binary signaling
head end
cable television operator has a central distribution point
DSL access multiplexer (DSLAM)
carrier needs to install this device to separate voice and data traffic, links voice to PSTN and link data to data network
access lines
connect hosts to the nearest switch; dominant for UTP
trunk lines
connect switches to other switches; mostly optical fiber
In optical fiber, light travels through the
core
What type of switch connects switches to other switches
core switches
two- way amplifiers
could carry data in both directions; allowed cable to compete in broadband service
longer propagation distances
create attenuation that results in lower SNR and therefore more noise errors
terminal crosstalk interference
crosstalk interference at the ends of the UTP cord, usually is much larger than the rest of crosstalk interference over the entire rest of the cord, therefore must not untwist UTP wires more than 1.25 cm when adding connectors to limit intereference, among 3 this one is the threat
The purpose of LLC subheader is to
designate the type of packet in the data field
Creating effective backup links in RSTP is
difficult and time consuming
What form of transmission is most resistant to transmission errors
digital
twisting each pair's wires
dramatically reduce interference, limiting to an acceptable level
If an Ethernet receiver detects an error in an arriving frame, it
drops the frame
Optical fiber cords use two strands
for full-duplex transmission
parallel transmission
for gigabit Ethernet, sending data simultaneously on two or more transmission lines in the same direction, speed is benefit.
The ability to transmit in two direction simultaneously is
full-duplex communication
Optical fiber's main advantage of UTP is
greater distance span
Switches in an Ethernet LAN are organized in a ___ topology
hierarchical
tempor
hierarchical
hertz (Hz)
how frequency is measured, one of these is =one cycle per second
nanometers (nm)
how wavelengths are measured, one billionth of a meter
signal to noise ratio (SNR)
if a signal is far larger than the noise floor then we have a high? , that means a a few random noise spikes will be large enough to cause errors
serial transmission
if one pair of wires is used to send a transmission, this is ? because the transmitted bits must follow one another in series, for slower Ethernet that run at 10 to 100 mbps
Ethernet is inexpensive thanks to
its hierarchical topology
optical fiber transmission
laser light is reported in wavelengths
frequency
light waves which is the number of times the wave goes through a complete cycle per second
UTP propagation distance
limit to 100 meters at all speeds up to 1 Gbps, the signal still will be comfortably larger than noise floor when it arrives at receiver so there will be few noise errors
2- pair data-grade UTP
local loop uses this technology; data grade meaning carriyny data instead of voice
Ethernet becomes the dominant of LAN technology primarily because of its
low cost, compared with competing technologies
When the light energies of two pulses arrive at overlapping times, this is
modal dispersion
noise spikes
much higher or lower than the noise floor
Modal dispersion limits transmission distance in
multimode fiber
crosstalk interference
mutual interference among wire pairs in a UTP cord or between wire pairs in a cord
perfect internal reflection
no light escapes into the cladding or beyond
optical fiber
normally used to carry signals farther, not faster
A local area network operates
on a customer premises
At what layer is the 100BASE-TX standard
physical
Ethernet standards are specified at the ___ layer
physical and data link
Ethernet usually has a 100 meter distance limit for
physical links
provisioning
providing service
UTP categories rate the ___ of UTP cabling
quality
noise
random electromagnetic energy;receiver actually gets the total of the signal plus the noise, UNWANTED, WITHIN PROPAGATION MEDIUM
Managed Ethernet switches ________
reduce hardware costs
asymmetric DSL (ADSL)
residential service with much higher download to the home speeds than upload speeds.
transceiver
sender/receiver
attenuated
signal has weakened; received signal differs from the transmitted, too much= receiver will not recognize it
distorted
signal's shape has been changed
Physical layer standards govern
signaling
amplitude
strength of the wave, measured as power
cladding
surrounding the core is a thicker glass cylinder, 125 microns in diameter,reflects the signal back into the core with perfect internal reflection so that no light escapes from the core.
Using priority in Ethernet requires the use of ___ fields
tag
Untwisting wire pairs no more than 1.25cm at the ends reduces
terminal crosstalk interference
drop cable
the access line to individual homes is a thin coaxial cable and the resident connects it to their TV
propagation effects
the changes in the signal during propagation; if this is too large, the receiver will not be able to interpret the signal correctly
wavelength
the distance between comparable parts on two successive cycles-peak to peak, trough to trough. In optical fiber transmission, laser light is reported as this?
noise floor
the mean of the noise energy
fiber to home (FTTH)
to provide extremely high speeds to homes by running carrier-grade fiber from the end office switch to residential households
core
to send signals by injecting light into a very thin glass rod and are 8.3, 50, or 62.5 microns
splitter
to use DSL service effectively, user must plug a ? into each telephone jack
propagates
travelling of a signal down a transmission medium
In LANs, optical fiber typically is used in
trunk lines
In binary signaling the is (are) ___ state(s)
two
electromagnetic interference (EMI) or inteference
unwanted external electromagnetic energy coming from electrical motors, fluorescent lights, and even other nearby UTP cords. will also add to the signal energy and make signal unreadable
Which of the following can increase reliability considerable in an Ethernet LAN
using the Rapid Spanning Tree Protocol
The distance between two corresponding points in adjacent cycles is the
wavelength
digital subscriber line (DSL)
whenever data is transmitted over 1-pair voice-grade UTP. The subscriber line is the line already running to the residential premise
Under the standard, Ethernet switches can provide enough power over UTP for ________
wireless access points
What type of switch connects users to the network
workgroup switches
