chapter 4

network diagrams

graphical representations of a network's devices and connections.

UTP(unshielded twisted pair)

is a type of copper-based cable that consists of one or more insulated twisted-wire pairs encased in a plastic sheath.

rack units(RU or U)

is the measure of racks, with the industry standard being 42U tall-about 6 feet. you may also see half-racks, which are only 18U-22U tall.

cable trays

metal trays built into equipment racks, office desks, or even along the ceiling to help collect cables into a single track.

standby UPS(standby power supply(SPS) )

provides continuous voltage to a device by switching virtually instantaneously to the battery when it detects a loss of power from the wall outlet.

rack systems

provides mounting hardware for network equipment to optimize the use of square footage in equipment rooms and ensure adequate spacing, access, and ventilation for these devices.generally you will see open frame two-post rack and four-post rack.

fault tolerance

refers to techniques that allow data storage or other operations continue in the event of a failure or fault of one of its components.

full-duplex(duplex)

signals are free to travel in both directions over a medium simultaneously. ex. talking on a phone is full duplex.

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 a one-way, or unidirectional, communication.

server rails

slides that make service access easier so that techs can slide servers out of the rack without completely removing them.

entrance facility

the location where an incoming network interface enters a building and connects with the buildings backbone cabling.

STP(shielded twisted pair)

type of copper-based cable containing twisted-wire pairs that are not only individually insulated, but also surrounded by a shielding made of a metallic substance such as foil.

loopback plug(loopback adapter)

used to test a nic or cable, plugs into a port such as an RJ-45 port, and crosses the transmit line with the receive line to test the port or cable for connectivity.

online UPS

uses AC power from the wall outlet to continuously charge its battery , while providing power to a network device through its battery. the devices relies on the UPS for its power.

horizontal wiring

wiring that connects workstations to the closet data closet.

rectifier

coverts AC to DC. all computers require the constant flow of electricity that DC power provides.

UPS(uninterruptible power supply)

a battery-operated power source directly attached to one or more devices and to a power supply, such as a wall outlet, that prevents undesired fluctuations of the wall outlet's AC power from harming the device or interrupting its services.

SAN(storage area networks)

a distinct network of storage devices that communicate directly with each other and with other networks. it is the most fault-tolerant type of topology possible.

fiber optic cable

a form of cable that contains one or several glass or plastic fibers in its core and comes in two types: single mode fiber(smf) or multiple mode fiber(mmf).

IDF(intermediate distribution frame)

a junction point between the MDF and end user equipment.

network mapping

a process of discovering and identifying the devices on a network.

NAS(network attached storage)

a specialized storage device or group of storage devices that provide centralized fault-tolerant data storage for a network.(think of it as a unique type of server dedicated to data sharing.) advantages are it contains own file system that is optimized for saving and serving files. it reads and writes from its disk significantly faster than other types of servers. another advantage is it can be easily expanded without interrupting service.

iSCSI(internet SCSI)

a transport layer protocol that runs on top of TCP to allow fast transmissions over LANs, WANs, and the internet. can work with twisted pair ethernet with ordinary ethernet NICs.

fibre channel(FC)

a transport layer protocol used on fiber-optic media instead of TCP or UDP. fibre channel connects devices within the SAN and also connects the SAN to other networks.capable of over 5 GBPS.

EMI(electromagnetic interference)

a type of interference that may be caused by motors, power-lines, televisions, copiers, fluorescent lights, or other sources of electricity.

MDF(main distribution frame)

also known as main cross connect, the first point of interconnection between an organization's LAN or WAN and a service provider's facility.

TIA/EIA

also known as structured cabling, describes the best way to install networking media to maximize performance and minimize upkeep.(Telecommunications industry association/electronic industries alliance)

inverter

converts DC to AC. a generator might contain a inverter.

transformer

changes the voltage of AC, such as when the power over the main line from electricity company is transformed before being delivered.

KVM(keyboard, video, and mouse switch)

connects to a single console to provide a central control portal for all devices on the rack.