Chapter 5

APC

Angle Polished Connector. The latest advancement in ferrule technology that uses the principles of reflection to its advantage by placing the end faces of the highly polished ferrules at an angle to each other, thus reducing the effect of the back reflection.

F-connectors

Attach to coaxial cable so that the pin in the center of the connector is the conducting core of the cable. Therefore, F-connectors require that the cable contain a solid metal core. Most often used with RG-6 cables.

Twisted-pair

Color-coded pairs of insulated copper wires, each with a diameter of 0.4 to 0.8 mm. Every two wires are twisted around each other to form pairs, and all the pairs are encased in a plastic sheath.

SFP+

Developed later than XFP and is the same module size as SFP; theoretical maximum transmission speed is 16 Gbps.

jitter

A transmission flaw caused by packets experiencing varying amounts of delay and arriving out of order. Also called PDV (packet delay variation).

loopback adapter

A troubleshooting tool that plugs into a port (for example, an RJ-45 or fiber-optic port) and crosses the transmit line with the receive line, allowing outgoing signals to be redirected back into the computer for testing. Also called a loopback plug.

Cat 6

10 Gbps, 250 MHz, includes a plastic core to prevent crosstalk between twisted pairs in the cable. Can also have foil insulation that covers the bundle of wire pairs, and a fire-resistant plastic sheath.

Cat 6a

10 Gbps, 500 MHz, reduces attenuation and crosstalk and allows for potentially exceeding traditional network segment length limits. Can reliably transmit data at multigigabit per second rates. Backward compatible with Cat 5, Cat 5e, and Cat 6 cabling, which means that it can replace lower-level cabling without requiring connector or equipment changes.

Cat 7

10 Gbps, 600 MHz, supports higher frequencies because each wire pair is wrapped in its own shielding, then packaged in additional shielding beneath the sheath. Requires more sophisticated connectors, either GG45, which is backward compatible with RJ-45, or TERA, which is not. It's larger and less flexible than earlier versions, and is also less common.

XFP

10 Gigabit small form-factor pluggable. Supports up to 10 Gbps and is slightly larger than SFP with lower power consumption than SFP+.

Cat 3

10 Mbps, up to 16 MHz, used for 10-Mbps Ethernet or 4-Mbps Token Ring networks. Rarely found on any modern network.

Cat 5

100 Mbps, 100 MHz, required minimum standard for Fast Ethernet.

Cat 5e

1000 Mbps, 350 MHz, a higher-grade version of Cat 5 wiring that contains high-quality copper, offers a higher twist ratio, and uses advanced methods for reducing crosstalk.

Ethernet Standards Used With Twisted-Pair Cabling

100Base-T Fast Ethernet Max speed: 100Mbps Max distance: 100m Physical media: Cat 5 or better Pairs of wires used for transmission: 2 pair 1000Base-T Gigabit Ethernet Max speed: 1000Mbps Max distance: 100

Cat 7a

40-100 Gbps, 1000 MHz, Not included in TIA/EIA standards, ISO standards for Cat 7a cabling are still being drafted and simulations conducted.

RG-6

75 ohms, 18 AWG conducting core, usually made of solid copper, used to deliver broadband cable Internet service and cable TV, particularly over long distances. Cable Internet service entering your home is RG-6.

RG-59

75 ohms, 20 or 22 AWG core, usually made of braided copper, still used for relatively short connections, for example, when distributing video signals from a central receiver to multiple monitors within a building. RG-59 is less expensive than the more common RG-6, but suffers from greater attenuation.

crossover cable

A twisted-pair patch cable in which the termination locations of the transmit and receive wires on one end of the cable are reversed as compared with the other end.

TIA/EIA 568B

A standard pinout for RJ-45 plugs commonly used in homes and businesses. White/orange Orange White/green Blue White/blue Green White/brown Brown

TIA/EIA 568A

A standard pinout for RJ-45 plugs required by the federal government on all federal contracts. White/green Green White/orange Blue White/blue Orange White/brown Brown

Fast Ethernet

A type of Ethernet network that is capable of 100-Mbps throughput.

Gigabit Ethernet

A type of Ethernet network that is capable of 1000-Mbps, or 1-Gbps, throughput. Requires Cat 5e or higher cabling.

coaxial cable

A type of cable that consists of a central metal conducting core, surrounded by an insulator, shielding, and an outer cover. Today coaxial cable, called "coax" for short, is used to connect cable Internet and cable TV systems.

crimper

A tool used to attach a connector onto the end of a cable, causing the internal RJ-45 pins to pierce the insulation of the wires, thus creating contact between the conductors at each wire.

QSFP+

Generally the same technology as QSFP while supporting data rates over 40 Gbps. Highest speed format at the time of this writing is QSFP28 with a total theoretical maximum data rate of 112 Gbps (4 x 28 Gbps).

GBIC

Gigabit interface converter. A standard type of modular interface that may contain RJ-45 or fiber-optic cable ports (such as LC, SC, or ST). They are inserted into a socket on a connectivity device's backplane.

RTT

Round Trip Time. The length of time it takes for a packet to go from sender to receiver, then back from receiver to sender. RTT is usually measured in milliseconds.

attenuation

The loss of a signal's strength as it travels away from its source.

throughput

The measure of how much data is actually transmitted during a given period of time.

twist ratio

The number of twists per meter or foot in a twisted-pair cable.

SC

subscriber connector or standard connector. A connector with a 2.5mm ferrule that is used with single-mode, fiber-optic cable.

BNC connector

A coaxial cable connector type that uses a turn-and-lock (or bayonet) style of coupling. BNC connector provides its own conducting pin. BNC connectors are used with RG-59 coaxial cables, and less commonly, with RG-6.

media converter

A device that enables networks or segments running on different media to interconnect and exchange signals.

multiplexing

A form of transmission that allows multiple signals to travel simultaneously over one medium.

modal bandwidth

A measure of the highest frequency of signal a multimode fiber can support over a specific distance and is measured in MHz-km.

PoE+

A method of delivering more current (up to 25.5 watts) than PoE does to devices using Ethernet connection cables.

transceiver

A modular interface that can be inserted in a switch to connect its motherboard with an external, fiber-optic cable.

TX/RX reverse

A problem caused by mismatched pinout standards, resulting in near end crosstalk.

multimeter

A simple instrument that can measure multiple characteristics of an electric circuit, including its resistance and voltage.

bit rate

In digital transmissions, a measurement of throughput and bandwidth that is expressed as bits transmitted per second.

MTRJ

Mechanical Transfer-Registered Jack. The most common type of connector used with multimode fiber-optic cable.

full-duplex

Signals are free to travel in both directions over a medium simultaneously.

half-duplex

Signals may travel in both directions over a medium but in only one direction at a time.

simplex

Signals may travel in only one direction, and is sometimes called one-way, or unidirectional, communication.

3 common types of multiplexing used on copper lines are:

TDM (time division multiplexing) - Divides a channel into multiple intervals of time, or time slots. Time slots are reserved for their designated nodes regardless of whether the node has data to transmit. STDM (statistical time division multiplexing) - Assigns time slots to nodes (similar to TDM), but then adjusts these slots according to priority and need. FDM (frequency division multiplexing) - Assigns different frequencies to create multiple frequency bands, each used by a subchannel, so that multiple signals can transmit on the line at the same time.

802.3at

The IEEE standard that improves upon the older 802.3af by supplying more power (up to 25.5 watts) over Ethernet connections.

802.3af

The IEEE standard that specifies a way of supplying electrical power (up to 15.4 watts) over twisted-pair Ethernet connections, also known as PoE (Power over Ethernet).

bandwidth

The amount of data that could theoretically be transmitted during a given period of time.

optical loss

The degradation of a light signal on a fiber-optic network as it travels away from its source.

ferrule

The extended tip of a fiber-optic connector that makes contact with the receptacle in the jack or other connector.

cladding

The glass or plastic shield around the core of a fiber-optic cable. Cladding reflects light back to the core in patterns that vary depending on the transmission mode.

UPC

Ultra Polished Connector. A type of ferrule in which the tip has been highly polished, thereby increasing the efficiency of the connection.

3 types of multiplexing used with fiber-optic cable:

WDM (wavelength division multiplexing) - Works with any fiber-optic cable to carry multiple light signals simultaneously by dividing a light beam into different wavelengths, or colors, on a single fiber. DWDM (dense wavelength division multiplexing or dense WDM) - Increases the number of channels provided by normal WDM to between 80 and 320 channels. Dense WDM can be amplified en route and is typically used on high-bandwidth or long-distance WAN links, such as the connection between a large ISP and its (even larger) NSP (network service provider). CWDM (coarse wavelength division multiplexing or coarse WDM) - Lowers cost by spacing frequency bands wider apart to allow for cheaper transceiver equipment.

tone locator (probe)

a device that emits a tone when it detects electrical activity on a wire

tone generator (toner)

a small, electronic device that issues a signal on a wire

cable performance cable

a troubleshooting tool that tests cables for continuity, but can also measure crosstalk, attenuation, and impedance; identify the location of faults; and store or print cable testing results. Also called line tester, certifier, or network tester.

CFP

centum form-factor pluggable. Intended for 100-Gbps network connections, with each succeeding generation (CFP, CFP2, CFP4) becoming smaller and more energy-efficient. Centum is Latin for 100.

alien crosstalk

crosstalk that occurs between two cables

FEXT

far end crosstalk. Crosstalk measured at the far end of the cable from the signal source.

FDP

fiber distribution panel. A device on a rack where fiber cables converge, connect with each other, and connect with fiber-optic terminal equipment from the ISP.

A typical fiber termination kit might include the following tools:

fiber stripper - strips off the outer layers of a fiber-optic cable fiber cleaver - cuts a clean slice through the fiber strands

LC

local connector. 1.25mm ferrule connector, which is used with single-mode, fiber-optic cable.

MMF

multimode fiber. Contains a core that is usually 50 or 62.5 microns in diameter, over which many pulses of light generated by a laser or LED travel at different angles. Not suited for long distances.

NEXT

near end crosstalk. Cross talk that occurs between wire pairs near the source of a signal

OPM

optical power meter or light meter. A device that measures the amount of light power transmitted on a fiber-optic line.

OTDRs

optical time domain reflectometers. A performance testing device for use with fiber-optic networks which can accurately measure the length of the fiber, locations of faults, and many other characteristics.

QSFP

quad small form-factor pluggable. Complies with the 802.3ba standard, squeezing four channels in a single transceiver and supporting data rates up to 40 Gbps (4 x 10 Gbps).

RFI

radio frequency interference. A kind of electromagnetic interference that can be generated by broadcast signals from radio or TV antennas.

SMF

single mode fiber. A type of fiber-optic cable with a narrow core of 8 to 10 microns in diameter that carries light pulses along a single path from one end of the cable to the other end.

SFP

small form-factor pluggable. Provides the same function as GBICs and is more compact, allowing more ports per linear inch. Also known as mini GBICs or SFP GBICs. Typically used for 1 Gbps connections, but theoretically capable of 5 Gbps.

ST

straight tip. A connector with a 2.5mm ferrule that is used with single-mode, fiber-optic cable.

TDR

time domain reflectometer. A high-end instrument for testing the qualities of a cable.