Explain Network Cable Types

Question 1

Unshielded Twisted Pair

Answer 1

The most popular type of network cable is of a copper wire construction called “ unshielded twisted pair” (UTP) . UTP is made up of four copper conductor wire pairs. Each pair of insulated conductors is twisted at a different rate from the other pairs, which reduces interference.

The electrical signaling method is only reliable over limited range. The signal suffers from attenuation, meaning that it loses strength over long ranges. Most UTP cable segments have a maximum recommended distance of 100 m (328 feet).

Question 2

Shielded Twisted Pair

Answer 2

Shielded twisted pair (STP) provides extra protection against interference. Shielded cable is often used for 10G Ethernet and higher within datacenter networks because it is more reliable than UTP.
Shielded cable can be referred to generically as “STP,” but several types of shielding and screening exist:

—Screened cable has one thin outer foil shield around all pairs. (F/UTP), or sometimes just foiled twisted pair (FTP)

—Fully shielded cabling has a braided outer screen and foil-shielded pairs. (S/FTP). There are also variants with a foil outer shield (F/FTP).

Question 3

Cat Standards

Answer 3

Cat __Max. Transfer Rate _Max. Distance
5_____100Mbps ____________100m
5e____1Gbps________________100m
6______1Gbps________________100m
_______10Gbps ______________55m
6A _____10Gbps ______________100m

Question 4

Rj45

Answer 4

Twisted pair cabling for Ethernet can be terminated using modular RJ45 connectors. RJ45 connectors are also referred to as “8P8C,” standing for eight-position/eight-contact.

The TIA/EIA-568 standard defines two methods for terminating twisted pair: T568A/T568B.

A straight through Ethernet cable is wired with the same type of termination at both ends.

Using T568A at one end and T568B at the other creates a crossover cable. Crossover cables were once used to connect computers directly, but Gigabit Ethernet interfaces can perform the crossover automatically, even if standard cable is used.

Question 5

T568A

Answer 5

1.White/Green
2.Green
3.White/Orange
4.Blue
5.Blue/White
6.Orange
7.White/Brown
8.Brown

Question 6

T568B

Answer 6

1.Orange/White
2.Orange
3.Green/White
4.Blue
5.Blue/White
6.Green
7.Brown/White
8.Brown

Question 7

RJ11

Answer 7

Twisted-pair can also be used with RJ11 connectors. Unlike the four-pair cable used with Ethernet, RJ11 is typically used to terminate two-pair cable, which is widely used in telephone systems and with broadband digital subscriber line (DSL) modems.

Question 8

Structures Cabling

Answer 8

Structured cabling is a standardized approach to installing and managing the cabling infrastructure within a building or campus. It’s designed to provide a flexible and reliable foundation for voice, data, and other communication systems.

Data cable for a typical office is installed as a structured cabling system. With structured cabling, the network adapter port in each computer is connected to a wall port using a flexible patch cord. Behind the wall port, permanent cable is run through the wall and ceiling to an equipment room and connected to a patch panel. The port on the patch panel is then connected to a port on an Ethernet switch.

A structured cabling system uses two types of cable termination:

Patch cords are terminated using RJ45 plugs crimped to the end of the cable.
Permanent cable is terminated to wall ports and patch panels using insulation displacement connectors (IDC), also referred to as “punchdown blocks.”

Installing cable in this type of system involves the use of cable strippers, punchdown tools, and crimpers.

Question 9

Patch cord

Answer 9

Type of flexible network cable typically terminated with RJ45 connectors. Ethernet patch cords cannot be longer than five meters.

Question 10

Permanent cable

Answer 10

Type of solid network cable typically terminated to punchdown blocks that is run through wall and ceiling spaces.

Question 11

Cable Stripper and Snips

Answer 11

A cable stripper is designed to score the outer jacket just enough to allow it to be removed. Set the stripper to the correct diameter, and then place the cable in the stripper and rotate the tool once or twice. The score cut in the insulation should now allow you to remove the section of jacket.

Question 12

Punchdown Tool

Answer 12

A punchdown tool is used to fix each conductor into an IDC. First, untwist the wire pairs, and lay them in the color-coded terminals in the IDC in the appropriate termination order (T568A or T568B). To reduce the risk of interference, no more than ½” (13 mm) should be untwisted. Blades in the terminal cut through the insulation to make an electrical contact with the wire.

Question 13

Crimper

Answer 13

A crimper is used to fix a jack to a patch cord. Orient the RJ45 plug so that the tab latch is underneath. Pin 1 is the first pin on the left. Arrange the wire pairs in the appropriate order (T568A or T568B), and then push them into the RJ45 plug. Place the plug in the crimper tool, close it tightly to pierce the wire insulation at the pins, and seal the jack to the outer cable jacket.

Question 14

Cable Tester

Answer 14

Once you have terminated cable, you must test it to ensure that each wire makes good electrical contact and is in the correct pin position. The best time to verify wiring installation and termination is just after you have made all the connections. Identifying and correcting errors at this point will be much simpler than when you are trying to set up end user devices.

A cable tester is a pair of devices designed to attach to each end of a cable. It can be used to test a patch cord or connected via patch cords to a wall port and patch panel port to test the permanent link. The tester energizes each wire in turn, with an LED indicating successful termination. If an LED does not activate, the wire is not conducting a signal, typically because the insulation is damaged or the wire isn’t properly inserted into the plug or IDC. If the LEDs do not activate in the same sequence at each end, the wires have been terminated to different pins at each end.

Question 15

Toner Probe

Answer 15

Many cable testers also incorporate the function of a toner probe, which is used to identify a cable from within a bundle. This may be necessary when the cables have not been labeled properly. The tone generator is connected to the cable using an RJ45 jack and applies a continuous audio signal on the cable. The probe is used to detect the signal and follow the cable over ceilings and through ducts or identify it from within the rest of the bundle.

Question 16

Loopback Plug

Answer 16

A loopback plug is used to test a NIC or switch port. You can make a basic loopback plug from a 6” cable stub where the wires connect pin 1 to pin 3 and pin 2 to pin 6. When you connect a loopback plug to a port, you should see a solid link LED showing that the port can send and receive.

A loopback plug made from a cable stub is unlikely to work with Gigabit Ethernet ports. You can obtain manufactured Gigabit port loopback testers.

Question 17

Network Taps

Answer 17

A network tap is used to intercept the signals passing over a cable and send them to a packet or protocol analyzer. Taps are either powered(active tap) or unpowered(passive test access point).

Question 18

Passive test access point

Answer 18

A passive test access point (TAP) is a box with ports for incoming and outgoing network cabling and an inductor or optical splitter that physically copies the signal from the cabling to a monitor port. No logic decisions are made, so the monitor port receives every frame—corrupt or malformed or not—and the copying is unaffected by load.

Question 19

active TAP

Answer 19

An active TAP is a powered device that performs signal regeneration, which may be necessary in some circumstances. Gigabit signaling over copper wire is too complex for a passive tap to monitor, and some types of fiber links may be adversely affected by optical splitting. Because it performs an active function, the TAP becomes a point of failure for the links during power loss.

Question 20

SPAN

Answer 20

Network sniffing can also be facilitated using a switched port analyzer (SPAN)/mirror port. This means that the sensor is attached to a specially configured port on a network switch. The mirror port receives copies of frames addressed to nominated access ports (or all the other ports).

Question 21

Plenum Cable

Answer 21

A plenum space is a void in a building designed to carry heating, ventilation, and air conditioning (HVAC) systems. Plenum space is typically a false ceiling, though it could also be constructed as a raised floor. As it makes installation simpler, this space has also been used for communications wiring in some building designs.

Building regulations require the use of fire-retardant plenum cable in such spaces. Plenum cable must not emit large amounts of smoke when burned, be self-extinguishing, and meet other strict fire safety standards.

Data cable rated for plenum use under the US National Electrical Code (NEC) is marked as CMP on the jacket.

Question 22

Non-plenum

Answer 22

General purpose (non-plenum) cabling uses PVC jackets and insulation. Plenum-rated cable uses treated PVC or fluorinated ethylene polymer (FEP).

General-purpose cables are marked as CMG or MMG for PVC jackets, and CM or MP for plenum-rated cables.

Question 23

Direct Burial

Answer 23

Outside plant (OSP) is cable run on the external walls of a building or between two buildings. This makes the cable vulnerable to different types of weathering:

Direct burial cable is laid and then covered in earth or cement/concrete.
OSP cable types use special coatings to protect against UV and abrasion and are often gel filled to protect against temperature extremes and damp conditions. Direct burial cable may also need to be armored to protect against chewing by rodents.
Regular PVC cable should not be used.

Question 24

Optical Cabling

Answer 24

An optical fiber consists of an ultra-fine core of glass to convey the light pulses. The core is surrounded by glass or plastic cladding, which guides the light pulses along the core. The cladding has a protective coating called the “buffer.” The fiber optic cable is contained in a protective jacket and terminated by a connector.

Fiber optic connectors are quite easy to damage and should not be repeatedly plugged in and unplugged. Unused ports and connectors should be covered by a dust cap to minimize the risk of contamination.

Question 25

Single-mode fiber(SMF)

Answer 25

Single-mode fiber (SMF) has a small core (8–10 microns) and is designed to carry a long wavelength (1,310 or 1,550 nm) infrared signal, generated by a high-power, highly coherent laser diode. Single-mode cables support data rates up to 10 Gbps or better and cable runs of many kilometers.

Question 26

Multi-mode fiber (MMF)

Answer 26

Multi-mode fiber (MMF) has a larger core (62.5 or 50 microns) and is designed to carry a shorter wavelength infrared light (850 nm or 1,300 nm).
MMF does not support such high signaling speeds or long distances as single-mode and so is more suitable for LANs than WANs.

Question 27

Straight tip (ST)

Answer 27

Straight tip (ST) is a bayonet-style connector that uses a push-and-twist locking mechanism; it is used mostly on older multi-mode networks.

Question 28

Subscriber connector (SC)

Answer 28

Subscriber connector (SC) has a push/pull design that allows for simpler insertion and removal than fiber channel (FC) connector. There are simplex and duplex versions, though the duplex version is just two connectors clipped together. It can be used for single- or multi-mode.

Question 29

Lucent connector (LC)

Answer 29

Lucent connector (LC) is a small form factor connector with a tabbed push/pull design. LC is similar to SC, but the smaller size allows for higher port density.

Question 30

Coaxial Cabling

Answer 30

Coaxial (coax) cable is a different type of copper cabling, also carrying electrical signals. Where twisted pair uses balancing to cancel out interference, coax uses two conductors that share the same axis. The core signal conductor is enclosed by plastic insulation (dielectric), and then a second wire mesh conductor serves both as shielding from EMI and as a ground.

Coax is now mostly used for CCTV installations and as patch cable for Cable Access TV (CATV) and broadband cable modems. Coax for CATV installations is typically terminated using a screw-down F-type connector.

Question 31

F-type Connector

Answer 31

Screw down connector used with coaxial cable.