SCTE - Broadband TelecomCenter Specialist (BTCS) - Facilities section

Recommended

The conditions are narrower, and represent the target conditions at which the hardware environment should be maintained for optimal reliability and performance.

Allowable Specifications

Specifications are generally quite varied and define the maximum limit that the hardware should never exceed. Example, may accommodate warm temperatures, but that may not be best for the hardware to achieve the most reliable operation.

Humidity and temperature

What two metrics is the HVAC system trying to control in a facility?

Conductive anodic filament (CAF) Formation

is a well-studied phenomenon driven by chemical, humidity, voltage, and mechanical means.

Letent heat of fusion

The amount of heat to melt ice.

Cold Liquid HVAC

HVAC system is helpful in hot desert climates--taking air that needs to be cooled into the HVAC unit intake. The intake air goes through stages before it is sent to the data center.

Downflow Method

The most common airflow path used by CRAC units, a combination of return air entering the top of the unit and supply air being discharged from the bottom of the unit.

Discharged Air

air typically empties into a raised floor plenum below the electronic equipment racks. The air supply pressurizes the raised floor plenum and then exits through cold tiles, which are perforated floor tiles located next to the rack-mounted equipment.

Up-flow Method

The cold supply air from the unit can be discharged through the bottom, the front, or through the top. The warmer return air can also be configured to enter the CRAC unit from the front, the rear, or the top

Direct Expansion

What is the most common air conditioning system used in HVAC?

Infrastructure right-sizing

Matches growth with the capacity to optimize the investment.

N+2

If a HVAC system is built where there is one main system and two backup systems it would fall into which redundancy class?

Power usage effectiveness (PUE)

The ratio of the total amount of power that might be used by the headend or hub, to the power required for the critical or IT equipment--includes power used for lighting, cooling systems, power distribution.

PUE

total facility power used/total consumed power by IT equipment

Carbon Usage Effectiveness (CUE)

a ratio of the total carbon emissions due to the total energy consumption of the data center compared to the energy consumption of the data center's servers and IT equipment.

Water Usage Effectiveness (WUE)

a ratio of the annual water usage to how much energy is being consumed by the IT equipment and servers, and is expressed in liters/ kilowatt-hour (L/kWh).

2 AWG

gauge of wire should be used inside the facility to bound the equipment to the ground

National Fire Protection Association

The organization OSHA ask for help to create workplace electrical safety standards

Overage

can be the result of long-term problems that create swells, or, overvoltage can be thought of as an extended swell. Overvoltages are also common in areas where supply transformer tap settings are set incorrectly and loads were reduced.

Underage

result from long-term problems that create sags. The term "brownout" describes this problem and has been superseded by the term "undervoltage." Brownout is ambiguous in that it also refers to commercial power delivery strategy during periods of extended high demand. Undervoltages can create overheating in motors and lead to the failure of non-linear loads such as computer power supplies.

Power Spike

occurs when the power level rises above normal levels and then drops back to normal in less than one second.

Power Surge

occurs when the power level rises above normal levels and stays there for more than one or two seconds.

Power Quality

problems generally indicate that stray frequencies have entered the power system through bad cords or loose connections.

Red Cable

cable used in the upstream path

Humidity and temperature

The two metrics the HVAC system is controlling in a facility.

Ethernet

The standard is taking over for transport of digital signal in a headend.

Time-Division Multiple Access (TDMA)

The multiplexing is used by docsis 3.0 modems for upstream communications

satmux

places digital programming into one channel

Decimal

Is base 10 which equals 10 symbols/numerals or 0 to 9.

Hexadecimal

Is base 16 which equals 16 symbols--0-9 and A-F.

Binary

Is base 2 which equals 2 symbols, 0 to 1, referred to as off and on in digital.

Preamble

Allows time for the receiver (of an Ethernet frame) in each node to synchronize the receive data clock to the transmit data clock.

Start Frame Deliminator (SFD)

indicates the next byte is the start of the frame

Maximum Transmission Unit (MTU)

is the maximum amount of data that a Data Link Layer (Layer 2) frame such as Ethernet can transport

IP datagram

has a maximum size of 65,535 bytes

Maximum Segment Size (MSS)

is the maximum amount of data that can be placed in a Transmission Control Protocol (TCP) segment.

Carrier Sense Multiple Access/Collision Detection (CSMA/CD)

is used in Ethernet to allow one device at a time to "talk" on the wire.

collision domain.

A segment of the network where a single Ethernet packet can be transmitted

broadcast domain

A segment of the network where an Ethernet (e.g., FF:FF:FF:FF:FF:FF) or IP (e.g., 255.255.255.255) broadcast packet can be transmitted

64 Bytes

the minimum number of bytes for a valis ethernet frame, from the perspective of a switch.

Ethernet frames are concerned with this portion of an IP session

Each network segment and operate in a "hop-by-hop" manner; A-B, B-C, C-D, D-Z

5-4-3 rule of networking

a guideline for designing early, shared Ethernet networks that uses hubs and repeaters, not switches

1000Base-T

Four pairs of wires in category 5 or higher twisted pair cable, Does not follow the 5-4-3 rule of networking, one repeater.

10GBase-T

Requires category 6 or category 7 cabling, Very fast data transmission, lower cost than fiber-optic.

10Base-F

10 Mbps baseband transmission over fiber optics. (IEEE 802.3 Ethernet)

100Base-FX

100 Mbps baseband transmission over fiber optics. (IEEE 802.3u Fast Ethernet)

1000Base-X

Identifies various Gigabit Ethernet Physical Layer standards.

Frame Check Sequence (FCS)

a 32-bit value, calculated using a Cyclic Redundancy Check (CRC), that is appended to the end of a data frame to detect transmission errors

Cyclic Redundancy Check (CRC)

A mathematical process performed on outgoing frames based on the headers in the frame, where the resulting computation is placed in the FCS. Performed on incoming frame to detect corruption during transmission.

Layer 7

This layer of the OSI model interacts with protocols.