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