Chapter 3 Flashcards
What is a coaxial cable?
referred to as coax is a cable that consists of two conductors
one of the conductors is an inner insulated conductor
the inner conductor is surrounded by another conductor that is sometimes made of a metallic foil or woven wire
What benefit does a coax cable get from having an inner conductor shielded by the metallic outer conductor?
resistances to electromagnetic interference (EMI)
What exactly is EMI?
EMI is unwanted noise or interference in an electrical path or circuit caused by an outside source
The term electromagnetic interference (EMI) is sometimes used interchangeably with what term?
frequency interference (RFI)
What does the word impedance mean?
resistance
What are the three common types of coax cables?
RG-59
RG-6
RG-58
Describe a RG-59 coax cable
This coax cable is used for short distance.
It is not right for long distance applications because of its loss characteristics.
impedance of 75 ohms
Describe an RG-6 coax cable
used by local cable companies to connect individual homes to the cable company’s distribution network.
impedance of 75 ohms
Describe RG-58 coax cable
Has loss characteristics and distance limitations like those of RG-59
impedance of 50 ohms
this type of coax was popular with early 10BASE2 Ethernet networks
What is the name of cabling similar to coaxial cable that is less popular? describe it
twinaxial cabling
commonly called twinax
it uses two inner conductors instead of one
What are some common connectors used on coaxial cables?
BNC -Bayonet Neill-Concelman
F-connector
Describe the BNC connector that is used on coaxial cables
A bayonet neill-concelman connector can be used for a variety of applications, including as a connector in a 10BASE2 Ethernet network.
A bnc coupler could be used to connect two coaxial cables together back to back.
Describe the F-connector that is used on coaxial cables
An F-connector is often used for cable TV connections.
often referred to as F-type connector
What is today’s most popular LAN media type?
twisted-pair cable
Describe a twisted-pair cable
individually insulated copper strands are intertwined
What are the two categories of twisted-pair cable?
shielded twisted pair (STP)
and
Unshielded twisted pair (UTP)
Why is plenum rated cable used?
for adherence to fire codes
To define industry-standard pinouts and color coding for twisted-pair cabling what standard was developed?
TIA/EIA 568
The first iteration of the TIA/EIA-568 standard, which was released in 1991, has come to be known as what?
TIA/EIA 568 A
The 2001 updated standard of the TIA/EIA 568 became known as
TIA/EIA 568 B
What is the most commonly used color coding of wiring standard in the United States?
568B
If wires in a cable are not twisted or shielded, what would happen?
The cable can act as an antenna which might receive or transmit EMI
One option for supporting higher frequencies is to surround a twisted pair in a metallic shielding, similar to the outer conductor in a coaxial cable. What is this type of cable referred to as?
Shielded twisted-pair (STP) cable
In STP, the outer conductors shield the copper strands from EMI; however, the drawback of STP is ….
addition of the metallic shielding adds to the expense of the cable
How does unshielded twisted pair protect from EMI?
UTP protects from EMI differently from STP
instead of having the wires twisted and shielded by metallic shielding, the wires are simply twisted more tightly (that is more twist per centimeter)
Which is less expensive UTP or STP? Why?
UTP because it does not have the additional cost of the metallic shielding that STP has
UTP cables vary in their data -carrying capacity. What are common categories of UTP cabling?
CAT 5
CAT 5e
CAT 6
CAT 6a
CAT 7
CAT 8
At what speed can CAT 5 carry data?
155Mbps
Most CAT 5 cables consist of ____ pairs of 24-gauge wires.
4
On average, on a CAT 5, how many twist per cm does the wire have?
5
CAT 5 is commonly used in …
Ethernet 100BASE-TX networks which carry data at a rate of 100Mbps
CAT 5e is an updated version of CAT 5 that is commonly used for _______ networks, which carry data at a rate of _____.
1000BASE-T
1Gbps or 1000Mbps
CAT 5e offers reduced what compared to CAT 5
crosstalk
What similarity does CAT 6 share with CAT 5e?
they are both commonly used for 1000BASE-T Ethernet networks
Although some CAT 6 is made from the same 24-gauge wire (other uses 22 or 23), CAT 6 is different in that …
CAT 6 cable has thicker insulation and offers reduced crosstalk compared with CAT 5e
CAT 6a or augmented CAT6 supports twice as many frequencies as CAT 6 and can be used for _____ networks.
10GBASE-T
Rate of transmission of data of CAT 6a
10 billion bits per second (10Gbps)
Why is CAT 7 not as popular as other UTP cabling categories?
CAT 7 is not an IEEE standard
What is the data transmissions speed and distance limitation of CAT 7?
10Gbps over 100m
What is the data transmission speed of CAT 8?
40Gbps
What is the con of CAT 8s speed?
CAT 8 supports distances of only 30 to 36m, depending on the patch cables used
The short distances and very high speeds of CAT 8 are ideal for?
data center connections between high-speed multilayer switches
Most UTP cabling used in today’s networks is considered to be …
straight-through
What is a straight through?
RJ45 jacks at each end of a cable have matching pinouts
pin 1 is the same at each end
What is a crossover cable
swaps the transmit and receive wire pairs between the two ends of a cable
in Ethernet
1 to 3 —- 3 to 1
2 to 6 —- 6 to 2
in T1
1 to 4 —– 4 to 1
2 to 5 —– 5 to 2
What is a rollover cable?
pin mapping
1 to 8
2 to 7
3 to 6
4 to 5 …
used to connect to a console port to manage a device such as a router or a switch
What are the common connectors used on twisted-pair cables?
RJ45
RJ11
DB-9(RS-232)
Describe a RJ45 connector
A type 45 registered jack is an eight pin connector found in most ethernet networks.
However most only use four pins
Describe a RJ11 connector
A type 11 registered jack has the capacity to be a six-pin connector.
most RJ11 only have 2-4 conductors
found in most home telephone networks
Describe a DB-9(RS-232) connector
DB-9 is an older connector used for low-speed asynchronous serial communications
pc - printer
What is fiber optic cabling?
An alternative to copper cabling, which sends light through an optical fiber (typically made of glass).
What advantages come with using fiber optic cabling?
Fiber optic is immune to EMI since it uses light and not electricity.
Also, depending on the Layer 1 technology, fiber-optic can have greater range and greater data-carrying capacity
Lasers are often used to inject light pulses into fiber optic. What is the lower cost option to this?
LEDs
Fiber optic cables are generally classified according to their diameter and fall into one of two categories
Multimode fiber MMF
signal-mode fiber SMF
Usually wavelengths of light in an MMF cable are in the range ….
850-1300nm
The wavelengths of light in an SMF cable are usually in the range …
1310-1550nm
What can be used to connect two fiber cables, back to back?
a fiber coupler
When a light source, such as a laser, sends light pulses into a fiber-optic
cable, what keeps the light from simply passing through the glass and being
dispersed into the surrounding air?
different types of glass
there is an inner strand of glass (that is, a core) surrounded by an outer cladding of glass, similar to the construction of previously mentioned coaxial cable
The two glasses of fiber optic works because
the inner strand and the outer cladding have different indexes of refraction
What is the path that light take through a fiber-optic cable called?
mode of propagation
What would happen if pulses of light representing different bits travel down the cable using different modes of propagation?
it is possible that the bits will arrive out of order
The condition of bits arriving out of order due to different modes of propagation is called what?
multimode delay distortion
To mitigate multimode delay distortion, multimode fiber (MMF) is typically limited to what?
shorter distances than SMF
Single-mode fiber (SMF) eliminates the issue of multimode delay distortion by doing what?
having a core with a diameter so small that it only permits one mode of propagation
What is a downside to SMF?
cost
because SMF has to be manufactured to very exacting tolerances, you usually pay more for a given length of single-mode fiber optic cabling
What are some common connectors used on fiber-optic cables?
ST
SC
LC
MTRJ
Describe an ST (straight tip) connector
sometimes referred to as a bayonet connector because of the long tip extending form the connector
ST connector are most commonly used with ___.
MMF
How does an ST connector connect to a terminating device?
push the connector into the terminating equipment and then twisting the connector housing to lock it in place
What dose SC stand for?
subscriber connector
standard connector
square connector
How do you connect an SC connector?
push the connector into the terminating device; you can remove it by pulling the connector from the terminating device
What are the main types of SC?
APC
UPC
MTRJ
What can LC stand for?
Lucent connector
little connector
local connector
You connect a LC into a terminating device by ….
pushing the connecter into the terminating device
you can remove it by pressing the tab on the connector and pulling it out of the terminating device
What does MTRJ stand for?
media termination recommended jack
mechanical transfer registered jack
What make the MTRJ unique?
two fiber strands (a transmit strand and a receive strand) are included in a single connector
The type of connection impacts the quality of the fiber-optic transmission. List from basic to better the options for polishing styles of fiber-optic connectors.
physical contact (PC)
ultra physical contact (UPC)
angled physical contact (APC)
How do you connect a MTRJ?
pushing it into the terminating device; you can remove it by pulling the connector from the terminating device
What is the PC (physical contact) polishing styles back reflection?
-40dB
What is the UPC (ultra physical contact) polishing style back reflection?
-55dB
What is the APC (angled physical contact) back reflection?
-70dB
A popular implementation of Ethernet, in the early days, was called what?
10BASE5
10 referred to network throughput -10Mbps
BASE referred to baseband
5 indicated the distance limitation of 500m
The cable used in 10BASE5 was a larger diameter than most types of media. In fact, this network type became known as …
thicknet
Another early Ethenet implementation was 10BASE2. What is the distance limitation of this Ethernet implementation?
185m
The cabling used in 10BASE2 networks was significantly thinner and therefore less expensive than 10BASE5 cabling. As a result, 10BASE2 cabling was known as
thinnet or cheapernet
What is the bandwidth capacity of standard Ethernet?
10Mbps
10 million bits per second
What is Fast Ethernet bandwidth capacity?
100Mbps
100 million bits per sec
What is Gigabit Ethernet bandwidth capacity?
1Gbps
1 billion bits per sec
What is 10-Gigabit Ethernet bandwidth capacity?
10 Gbps duh
What is 100-Gigabit Ethernet bandwidth capacity?
100 Gbps duh
The type of cabling used in an Ethernet network influences what?
bandwidth capacity and distance limitation of the network
Between fiber optic and twisted-pair cabling, which often has a higher bandwidth capacity?
fiber-optic
What is a transceiver?
a device that makes it possible to uplink one Ethernet switch to another if different connectors for different installations are required
A GBICs is a transceiver with the bandwidth capacity of 1Gbps. What is the smaller variant of a regular GBIC called?
small form-factor pluggable (SFP)
which is sometimes called a mini GBIC
Name the variations of the SFP
Enhanced form-factor pluggable (SFP+)
Quad small form-factor pluggable (QSFP)
Enhanced quad small form-factor pluggable (QSFP+)
What does multiplexing do?
allows multiple communications sessions to share the same physical medium
What are the three approaches to multiplexing in fiber-optic networks?
Dense wavelength-division multiplexing (DWDM)
Coarse wavelength-division multiplexing (CWDM)
Bidirectional wavelength-division multiplexing (WDM)
Describe how Dense Wavelength-Division Multiplexing (DWDM) works
32 light wavelengths on a single fiber, where each wavelength can support as many as 160 simultaneous transmissions using more than eight active wavelengths per fiber
Describe how Coarse wavelength-division multiplexing (CDWM) works
CDWM uses fewer than eight active wavelengths per fiber
Describe how Bidirectional wavelength division multiplexing (WDM) works
This approach multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths.
Using this technique enables bidirectional communication over one strand of fiber and increases the overall capacity.
cable distribution systems are ____ in nature
hierarchical
What is a wiring closet?
the location where cables from end-users offices runs back too
What is a patch panel or patch bay?
A patch panel in a local area network (LAN) is a mounted hardware assembly that contains ports that are used to connect and manage incoming and outgoing LAN cable
What is punchdown blocks?
A common term for cross connect blocks.
A cross-connect is a physical, hardwired cable that provides a direct connection between two different termination locations within a data center.
What is a fiber distribution panel?
fiber optic patch panel, mainly used for accommodating fiber cable terminations, connections and patching
What are the two major categories of fiber distribution panels?
wall mount and rack mount
What are the common locations where cables from nearby offices terminate called?
intermediate distribution frames (IDFs)
What are the two most popular types of cross-connect blocks found in IDF?
66 block
110 block
Where were 66 blocks traditionally used and for what?
corporate environments for cross-connecting phone system cabling
As 10Mbps LANs grew in popularity, 66 blocks were used for what?
cross-connect CAT 3 UTP cabling
What is the downside to 66 blocks?
do not support higher speed LAN technologies, such as 100Mbps Ethernet networks
What are 110 blocks used for?
110 blocks are often used to terminate cable used for higher-speed LANs
Krone is a cross connect block that is the European alternative to the ____block.
110
What is a BIX?
a cross connect block that terminates 25 pairs
unused side is the only thing visible
The centralized distribution frame, which connects out to multiple IDFs, is called what?
main distribution frame (MDF)
