Module 2.5: Installation of wires/Troubleshooting Flashcards
(88 cards)
1
Q
What is the Order of wiring in the Standard T568A set up?
A
Pin1: GW - White with green stripes Pin2: G - Green Pin3: OW - White with orange stripes Pin4: B - Blue Pin5: BW - White with blue stripes Pin6: O - Orange Pin7: BrW - White with brown stripes Pin8: Brown
2
Q
What is is the order of wiring in the Standard T568B set up?
A
Pin1: OW - White with orange stripes Pin2: O - Orange Pin3: GW - White with green stripes Pin4: B - Blue Pin5: BW - White with blue stripes Pin6: G - green Pin7: BrW - White with brown stripes Pin8: Brown
3
Q
What is the difference in wiring a Straight-Through cable from a Crossover cable?
A
Straight-Through cables are wired exactly the same and both ends (with a twist in the center). A Crossover cable has 1 side with the T568A order and the other side as the T568B order.
4
Q
When would you use a Straight-Through cable?
A
Connecting computers to a hub/switch. This is the most common type of twisted pair cabling.
Also use this when you are connecting two different types of devices.
If there is an uplink port.
5
Q
When would you use a Crossover cable?
A
When no uplink port is available, a Crossover can use a regular port.
You can use a Crossover cable to connect two hubs together.
This connects two of the SAME type of device together.
6
Q
When do you use solid cores when installing cables?
A
When you need to run a longer cable inside walls or the ceiling.
7
Q
Which pins are used for a computer NIC which installing for a 10BASE-T or 100BASE-TX?
A
Pin1: Transmit + Pin2: Transmit - Pin3: Receive + Pin6: Receive - Pins 4,5,7,8 are unused.
8
Q
Which pins are used when installing for a 1000BASR-T or Gigabit ethernet(Cat5e or above)?
A
All pins are used. There are - and + for each wire so there is no designated Transmit and Receive pins.
9
Q
If Cat 7 cabling is being used for 10gigabit ethernet, with what connects are they terminated with?
A
GG45 or TERA
10
Q
What does PoE stand for?
A
Power over Ethernet
11
Q
When would you use a PoE?
A
When remote devices have no external power available.
Also used with digital telephone systems where handsets are powered through the Ethernet cable, eliminating the need for a separate power adapter.
12
Q
What does a PoE do?
A
Allows network cables to carry electrical power.
13
Q
What does LEC stand for?
A
Local Exchange Carrier
14
Q
What is a demarcation point?
A
The line that marks the boundary between the telco equipment or cable and you private network or telephone system.
Also known as MPOE (minimum point of entry) or EU-POT(end user point of termination)
15
Q
What is a demarc extension?
A
It’s to change the location of the demarc location if there are multiple floors or businesses that use the the same building.
16
Q
Who maintains the SmartJacks?
A
The LEC
17
Q
What is the purpose of SmartJacks?
A
Used for complex services such as a T1 line.
Provide signal conversions, buffer signals, and regenerate signals.
Provide diagnostic capabilities for the LEC.
18
Q
What does MDF stand for?
A
Main Distribution Frames
19
Q
What dose IDF stand for?
A
Intermediate Distribution Frames
20
Q
What is a MDF?
A
A frame, or rack, that is used to interconnect and manage telecommunication wiring in a building.
- Usually located on bottom floor or basement.
- All internet or WAN demarcation points are normally near, or within, the MDF.
21
Q
What is a IDF?
A
A smaller wiring rack, or frame, than the MDF.
22
Q
Where are the IDFs usually located?
A
Each floor directly above the MDF, though multiple can be added.
23
Q
When are vertical cross connections used?
A
When connecting an IDF that is directly above an MDF.
24
Q
What are punch down blocks?
A
Predecessors to patch panels. Commonly used to support low-bandwidth and ethernet and telephony wiring.
25
What are the two different 66 block configuration?
1: The 25-pair block (non-split block) = All four pins are bonded (electrically connected).
2: The 50 pair block( Split block) = Each set of two pins in a row are bonded.
26
When do you use a 25-pair block?
Use the 25 pair block to connect a single wire with up to three other wires.
27
When do you use a 50-pair block?
Use the 50 pair block to connect a single wire to one other wire.
28
When do you use a 66 block punch down?
When connecting individual copper wires together.
29
When do you use a 110 block punch down?
When connecting individual wires together.
30
When connecting wires on a 110 block, what is the order of wiring?
- White with blue stripe
- Blue
- White wire with orange stripe
- Orange
- White with green stripe
- Green
- White with brown stripe
- Brown
31
What are 110 blocks primarily used for?
Telephone applications.
32
What are 110 blocks preferable to 66 blocks in high speed networks?
Because they introduce less crosstalk.
33
What should you include in documentation of a MDF and IDF wiring config?
- Location
- Installation dates
- Cable lengths
- Cable grades
34
What is a patch panel?
A device that typically connects individual stranded wires into female RJ45 connectors.
35
What are some ways to avoid EMI?
- Use fiber optics
- Use shielded twisted pair cables.
- Use a drain wire
- Avoid installing cables near EMI/RFI sources
36
What are some ways to avoid crosstalk?
- Tighter twists in the wires
- Twist each pair at a different rate
- Avoid damaged coating and connectors
37
What does NEXT stand for?
Near-end crosstalk.
38
What does NEXT measure?
Interference on an adjacent wire pair at the same connector end.
39
What does FEXT stand for?
Far-end crosstalk.
40
What does FEXT measure?
Interference on an adjacent wire pair at the opposite connector end.
41
What is Attenuation?
The loss of signal strength from one end of a cable to the other.
42
What causes attenuation?
- Length of cable
| - High temp
43
What is Impedance?
The measure of resistance within the transmission medium.
44
What unit do you measure impedance with?
Ohms.
45
True or False:
| All cables must have the same impedance rating.
True.
46
What happens when cables of different impedance ratings react with one another?
Signals can be reflected back toward the original source, distorting signals. example: Tv with impedance can cause ghosting of the image.
Distance does not effect impedance.
47
What is a short?
When signals take a path other than the intended path. In the case of twisted pair wiring a short means that a signal sent on one wire arrives on a different wire.
48
How do shorts occur?
When two wires touch; caused by worn jackets, crushed wires, or a metal object piercing two or more wires.
49
What is an open circuit?
When a cut in the wire prevents the original signal from reaching the end of the wire.
50
How is a short and an open circuit different?
An open circuit is different from a short in that the signal stops completely; electricity cannot flow due to a complete disconnection.
51
What is a reverse connection?
When a cable is wired using one standard on one end and another standard on the other end, creating a crossover cable. This problem only occurs when a straight-through cable is needed.
52
What is a split pair condition?
When a single wire in two different pairs is reversed at both ends. This doesn't necessarily mean it won't work, but it could introduce crosstalk.
53
What is an easy way to avoid a split pair issue?
Use a punch down block.
54
What is am Incorrect Termination?
This occurs when an incompatible or incorrect connector is used. This results in reduced performance or complete connection loss.
55
Explain what a bad connector is.
A bad connector is a damaged connector that is causing connectivity issues. For example, a broken locking tab on an RJ45 connector can cause intermittent connection problems. Another common connector is when there is a bent or damaged pin, especially on female RJ45 connections and the center wire of a coaxial cable.
56
Explain what a Transceiver mismatch is.
Well-manufactured network devices have interfaces that can be tailored to different cable types, protocols, and speeds. This is done by connecting a hot swappable transceiver to the interface. When connecting one network device to another, matching transceivers must be used. For twisted pair cabling, a mismatch in speed is a common issue.
57
How do you clean a FC connector for fiber optics?
Where the ferrule protrudes, wipe the end of the ferrule with a lint-free cloth that has a small amount of denatured alcohol applied. Immediately wipe the ferrule dry.
58
How do you clean a fiber optic connector if the end of the ferrule is less accessible?
Must use a specialized cleaning tool.
59
What is insertion loss?
Whenever a connector is installed on the end of fiber optic cable, a degree of signal loss occurs.
60
What is back-reflection or optical return loss (ORL)?
When some of the light that is lost is reflected directly back down the cable, towards the source.
61
Describe the PC polish grade.
PC stands for Physical Contact. It is usually used with single-mode fiber. The ends of the fiber are polished with a slight curvature so that when the cable end is inserted into the connector, only the cores of the fiber actually touch each other.
62
Describe the SPC and UPC polish.
use higher grade polish and have more curvature than PC polishing.
63
Describe APC polishing.
Stands for Angled physcial contact. It's used to reduce back reflection as much as possible. An APC connector has an eight degree angle cut into the ferrule, which prevents reflected light from traveling back down the fiber. Any reflected light is bounced out into the cable cladding instead. You can only use APC connectors with other APC connectors, otherwise it would result in excessive insertion loss.
64
APC connectors are what color?
Green.
65
Why is using fiber optics harder than copper wiring?
Fiber optics are fragile and can be easily damaged.
66
Can you mix single-mode with multi-mode cables?
No. This introduce a catastrophic signal loss of up to 99%.
67
Can you mix the same type of cable, but with different core sizes? Why or why not?
No. If two cables of the same type, but with different sized cores, are connected this can result in a loss of signal strength of up to 50%.
68
What is a GBIC?
This is a gigabit interface converter transceiver. They can be inserted into network switches and routers to convert the interface from copper wiring to fiber optics.
69
What is a SFP?
Stands for small form-factor pluggable transceiver. This also allows interface to be converted from copper wiring to fiber optics.
70
What are some issues with GBIC/SFP transceivers?
- You must use the correct fiber with the correct transceiver since they may use different types and sizes.
- Known to malfunction occasionally.
71
What are some ways that light loses energy, or ways that incur signal loss in a fiber optic?
- Reflection: A measurable amount of light is reflected when it hits the ends of the cable. Much of a cable's reflection loss occurs at each cable connection. When the light hits the boundary between the core and the cladding, it is reflected back into the core. There is minor loss to the signal when this occurs, but it contributes to overall signal loss.
- Refraction: f the light hits the boundary between the core and the cladding at too steep of an angle, the light is refracted into the cladding instead of reflected back into the core, causing signal loss. Some fiber optic cables are doped with impurities near the edge of the fiber so that the signals are bent instead of reflected back to the center of the core. The loss due to this refraction is minor when compared with the benefits of confining the light to the center of the core.
- Scattering: Impurities in the fiber core can cause light to scatter. Some of the light continues down the fiber. The light that is scattered backwards contributes to the signal loss.
- Absorption: Impurities in the fiber can also absorb the light, converting it to another form of energy, like heat. This is a major cause of signal loss.
72
What are some physical attributes the can contribute to signal loss?
- Cable length: while higher quality cables will carry light signals further, the longer the cable, the more signal absorption and the greater the signal loss.
- Connectors: every connector will cause some level of signal loss, mostly due to reflection. While patch cables at each end of a run are to be expected, you should minimize any other connections.
- Splices: there are tools that you can use to splice a cut fiber optic cable. However, the signal loss from a splice is comparable to the signal loss from a connector.
- Bends: micro bends in the cable due to things such as temperature change or manufacturing anomalies can cause signal loss. While you have little control over micro bends, even macro bends, those detected by the human eye, can contribute to signal loss. The straighter the fiber optic cable, the less the signal loss.
73
What is the avg signal loss with connectors?
0.3 dB with each connector.
74
What is the avg signal loss with splices?
0.3 dB
75
What is the avg signal loss with mutli-mode cabling?
3 db loss per 1000 meters when using an 850 nm light source.
| 1 db loss per 1000 meters when using a 1300 nm light source.
76
What is the avg signal loss with single-mode cabling?
0. 5 dB loss per 1000 meters when using a 1310 nm light source.
0. 4 dB loss per 1000 meters when using a 1550 nm light source.
77
What is the recommended max attenuation that should be allowed? (Link-loss margin)
No more than 3 dB less that the total power at the transmission source.
ex: If total power output at the transmission source of a cable run is 15dB, then the total attenuation over the cable run should not exceed 12dB.
78
What does a Loopback plug do?
A loopback plug, or loopback adapter, reflects a signal from the transmit port on a device to the receive port on the same device. Use the loopback plug to verify that a device can both send and receive signals.
- There are loopback plugs for both copper and fiber connections.
- A failure in the loopback test indicates a faulty network card.
- A successful loopback test means the problem is in the network cabling or another connectivity device.
You can purchase pre-made loopback plugs, or you can make an inexpensive one by cutting the end off a cable and manually connecting the transmit wires to the receive wires (connect the wire from pin 1 to the wire at pin 3, and the wire at pin 2 to the wire at pin 6).
79
What is a Smartjack?
A smartjack is an intelligent loopback device installed at the demarcation point for a WAN service. Technicians at the central office can send diagnostic commands to the smartjack to test connectivity and performance between the central office and the demarc. When you contact a WAN service provider for assistance, they might execute a test using the smartjack. A successful test indicates that the problem is within your customer premises equipment (CPE).
80
What is a cable tester?
A cable tester (or line tester) verifies that the cable can carry a signal from one end to the other and that all wires are in the correct positions.
- High-end cable testers can check for various miswire conditions (wire mapping, reversals, split pairs, shorts, or open circuits).
- You can use a cable tester to quickly tell the difference between a crossover and a straight-through cable..
- Most testers have a single unit that tests both ends of the cable at once. Many testers come with a second unit that can be plugged into one end of a long cable run to test the entire cable.
81
What is a TDR?
A time-domain reflectometer is a special device that sends electrical pulses on a wire in order to discover information about the cable. The TDR measures impedance discontinuities (the echo received on the same wire in response to a signal on the wire). The results of this test can be used to identify several variables:
- Estimated wire length
- Cable impedance
- The location of splices and connectors on the wire
- The location of shorts and open circuits
82
What is an OTDR?
An optical time-domain reflector performs the same function as a TDR, but is used for fiber optic cables. An OTDR sends light pulses into the fiber cable and measures the light that is scattered or reflected back to the device. The information is then used to identify specifics about the cable:
- The location of a break
- Estimated cable length
- Signal attenuation (loss) over the length of the cable
83
What is a Cable Certifier?
A cable certifier is a multi-function tool that verifies that a cable or an installation meets the requirements for a specific architecture implementation. For example, you would use a certifier to verify that a specific drop cable meets the specifications for 1000BaseT networking.
- A certifier is very important for Cat 6 cable used with bandwidths at or above 1000 Mbps. Slight errors in connectors or wires can cause the network to function at 100 Mbps instead of the desired 1000 Mbps or 10 Gbps.
- Certifiers can also validate the bandwidth capabilities of network interface cards and switches. Many can detect the duplex settings of network devices.
- Most certifiers include features of a toner probe, TDR, and cable tester.
- Certifiers are very expensive and are typically used by organizations that specialize in wiring installations.
84
What is a Toner Probe?
A toner probe is composed of two devices that are used together to trace the end of a wire from a known endpoint to the termination point in the wiring closet. To use a toner probe:
- Connect the tone generator to one end of the wire. It will send a signal on the wire.
- In the wiring closet, touch the probe to wires or place the probe close to wires. A sound at the probe indicates that the generated tone has been detected and the wire that you are touching is the termination point for the wire you are tracing.
85
What is a Multimeter?
A multimeter is a device used to test various electrical properties. A multimeter can measure several parameters:
- AC and DC voltage
- Current (amps)
- Resistance (ohms)
- Capacitance
- Frequency
86
What is a Voltage Event Recorder?
A voltage event recorder keeps track of voltage conditions on a power line. Basic recorders simply keep track of the occurrence of under-voltage or over-voltage conditions, while more advanced devices track conditions over time and create a graph, saving data from a program running on a computer.
Some UPS systems include a simple voltage event recorder. Use a voltage event recorder to identify periods of low or high voltage that can adversely affect network components.
87
What is an Environmental Monitor?
An environmental monitor does what its name implies—it monitors the environmental conditions of a specific area or device.
- Monitors are often used to track the conditions within server rooms (such as temperature, humidity, water, smoke, motion, and air flow).
- Typically computers, especially servers, have an internal monitor that measures fan speed and CPU temperature.
- Many monitors will sound an alarm if a specified temperature or other environmental condition is reached.
88
What is a Speed Test Website?
A speed test website is an online tool that is used to test the bandwidth of your internet connection. There are countless speed test websites available, all of which provide essentially the same information:
- Connection latency (ping)
- Download speed
- Upload speed
