TUTORIAL 2 - Network Media Flashcards
what is the criteria of choosing network media
- bandwidth rating
- max segment length
- interference & eavesdropping susceptibility
- cable grade
- connection hardware
- ease of installation
- testability
- total cost
bandwidth rating criteria
num of bits per sec that can be transmitted across medium
factor determining bandwidth is how bit signals represented on medium (called encoding)
when possible choose cabling category that’s compatible with the standard you want to implement now but will support growth & faster speeds
max segment length criteria
max cable length between 2 network devices
each cable type can transport data only so far before its signals begin to weaken beyond what can be read by a receiving device (attenuation)
intermediate passive devices (Eg. wall jacks) are part of total segment length
interference & eavesdropping susceptibility criteria
comes in form of electromagnetic interference (EMI) & radio frequency interference (RFI)
motors, transformers, fluorescent lights, or other sources of intense electrical activity can emit both EMI & RFI
RFI can also affect wireless networks if frequency in same range
Crosstalk - interference 1 wire generates on another when in bundle
copper wires susceptible to electronic eavesdropping
fiber-optic carry light signals so not susceptible to interference or eavesdropping
cable grade criteria
building & fire codes include specific cabling requirements
cables ran between false ceiling
true ceiling (plenum) must be plenum-rated
UTP cabling marked as communication cable riser (CMR) or comm cable plenum (CMP)
CMR can only be used for building risers/cable trays
CMP suitable for use in plenum spaces
connection hardware criteria
every type of cable has connectors that influence kinds of hardware cable can connect to
must make sure media selected can support network device
the types of cables
coaxial
shielded twisted
unshielded twisted
why must the twisted pair cable be twisted
consists of 1 or more pairs of insulated strands of copper wires twisted around 1 another & housed in outer jacket
twists necessary to improve resistance to crosstalk from wires & EMI from outside sources
more twists per unit length, better resistance to EMI & crosstalk
more expensive TP wisted more than less expensive
provides better pathway for higher bandwidth networks
tbh you won’t bother, just make sure its cat is high
what is a shielded twisted pair cable made of
includes shielding to reduce crosstalk & interference
has wire braid inside sheath material/foil wrap
best to use in electrically noisy environments/very high-bandwidth apps
what are the cable plant components in the twisted pair cables
RJ-45 connectors - STP & UTP uses registered jack 45
most commonly used in patch cables
used to connect computers to hubs, switches & RJ-45 wall jacks
Rj-45 jacks - what you plug an RJ-45 connector into when computer not near a switch/hub
usually placed behind wall plates when cables run inside walls
patch cable
short cable for connecting computer to RJ-45 wall jack or connecting a patch-panel port to switch/hub
can be made with inexpensive tols, 2 RJ-45 plugs & length of TP cable
patch panels
used to terminate long runs of cable from where computers are to wiring closet (where switches & hubs are)
distribution racks
hold network equipment
Eg. routers, switches, patch panels, rack-mounted servers etc.
AKA 19” racks as upright rails are 19” apart
Why is there a need for 2 transmit & 2 receive wires?
1 wire pair used for transmit (labeled transmit+/transmit-) and 1 pair for receive (labeled receive+/receive-)
plus & minus symbols indicate that wires carry positive & negative signal
this differential signal mitigates effect of crosstalk & noise on cable
fiber optic cables
immune to electrical interference
highly secure
electronic eavesdropping eliminated
composition
slender cylinder glass fiber called core surrounded by concentric layer of glass called cladding
fiber jacketed in thin transparent plastic material called buffer
each fiber-optic strand carries data in only 1 direction
network connections consist of 2 or more strands
fiber-optic cable used as backbone cabling often comes in bundles of 12 or more fiber strands
even only using 2 in backbone, running more is good idea so ready for future expansion
some testing shown that glass fibers can carry several terabits (1000 gigabits) per second
fiber-optic may 1 day replace copper for all types of network connections
what are the types of fiber optic connectors
straight tip (ST)
straight connection (SC)
locking connection (LC)
mechanical transfer registered jack (MT-RJ)
fiber channel or ferrule connector (FC)
medium interface connector (MIC)
subminiature type A (SMA)
installation of fiber optic cables
more difficult & time consuming than copper media installation
however advances in connector tech closing gap
connectors & test eq required for termination still more expensive than copper
many methods for terminating fiber-optic cables due to many connectors & cable types available
installation details beyond scope of this book
what are the types of fiber optic cables
single-mode fiber (SMF)
includes single, small-diameter fiber at core
8 microns
generally works with laser-based emitters
longest dist
used in higher-bandwidth apps
multimode fiber (MMF)
larger diameter fiber at core
50 & 62.5 microns
cheaper than SMF
works with lower-power light emitting diodes (LEDs)
shorter dist
what is structured cabling
specifies how cabling should be organized, regardless of media type or network architecture
large networks typically use most/all of these
work area
horizontal wiring
telecommunications closets
equipment rooms
backbone or vertical wiring
entrance facilities
what are work areas
where workstations & other user devices located
faceplates & wall jacks installed in work area
patch cable connect computers & printers to wall
what is horizontal wiring
runs from work area’s wall jack to telecomm closet
wiring from wall jack to patch panel should be no longer than 90 meters (plus 10m for patch cables)
what is a telecommunications closet
TC provides connectivity to computer equipment in nearby work area
typical eq includes
patch panels to terminate horizontal wiring runs
hubs
switches
TC that hosues cabling & devices for work area computers referred as intermediate distribution frame (IDF)
what is an equipment room
houses servers, routers, switches & other major network equipment
serves as connection point for backbone cabling
ea room that’s connection point between IDFs called main distribution frame (MDF)
MDF can be main cross-connect for entire network or serve as connecting point for backbone cabling between buildings
ea building has own MDF
what is backbone cabling
interconnects IDFs & MDFs
runs between floors/wings of building & between buildings
frequently fiber-optic cable but can also be UTP if dist between TC is < 90m
what is an entrance facility
location of cabling & equipment that connects a corporate network to 3rd party telecomm provider
can also serve as eq room & main cross-connect for all backbone cabling
where WAN connection made
demarcation point - point where corporate LAN eq ends & 3rd party provider’s equipment & cabling begins
installation of unshielded twisted cables
cable termination - putting RJ-45 plugs on ends of cable/punching down wires into terminal blocks on jack/patch panel
tools needed
o wire cutters
o crimping tool
o cable tester
o punchdown tool
o cable stripper
o RJ-45 plugs/jacks
when making cable/terminating cable at a jack or patch panel
important to get colored wires arranged in correct order
2 standards: 568A & 568B
differences between straight through and crossover cable
straight through:
same wiring standard on both ends
crossover:
use 568A standard on 1 side & 568B on other
crosses transmit & receives wires so that transmit on 1 end connects to receive on other
this type of cable often needed when you connect 2 devices of same type to 1 another
for 1000BaseT crossover cable, have to cross blue & brown pins as used in 1000BaseT
what are some cable-testing equipment and what are they used for
common tools for testing & troubleshooting wired networks
cable certifier
basic cable tester
tone generator
time domain reflectometer (TDR)
multimeter
optical power meter (OPM)
what is wireless networking
often used with wired to interconnect geographically dispersed LANs or groups of mobile users with wired servers & resources on wired LAN
AKA hybrid networks
AP or router usually connects to internet via wired connection to cable modem though clients through wireless
what are some wireless networking benefits
create temp connections to wired networks
establishes backup/contingency connectivity for existing wired networks
extends network’s span beyond reach of wire-based or fiber-optic cabling
especially in older buildings where rewiring might be too ex
allows businesses to provide customers with wireless networking easily, offering service that gets customers in & keeps them
enables users to roam around a corporate/college campus with their machines
what are the types of wireless networks
local area networks (LAN)
usually provides connectivity for mobile users or across areas that couldn’t otherwise be networked
extended LANs
usually used to increase LAN’s span beyond normal dist limitations
internet service
used to bring internet access to homes & businesses
mobile computing
users communicate by using wireless networking medium that enable them to move while remaining connected
what are some wireless LAN components
network interface attaches to antenna & emitter instead of cable
transceiver/access point (AP) - transmitter /receiver device must be installed to translate between wired & wireless networks
includes antenna & transmitter to send & receive wireless traffic but also connects to wired side of network
shuttles traffic back & forth between network’s wired & wireless sides
what is wireless LAN transmission
network interface attaches to antenna & emitter instead of cable
transceiver/access point (AP) - transmitter /receiver device must be installed to translate between wired & wireless networks
includes antenna & transmitter to send & receive wireless traffic but also connects to wired side of network
shuttles traffic back & forth between network’s wired & wireless sides
what is infrared LAN tech and what kinds are there
use infrared light beams to send signals between devices
works well for LAN apps due to high bandwidth
4 main kinds
line-of-sight networks - require unobstructed view between transmitter & receiver
reflective wireless networks - broadcast signals from optical transceivers near devices to central hub
scatter infrared networks - bounce transmissions offwalls & ceilings to deliver signals
broadband optical telepoint networks - provide broadband services
what is a laser-based LAN tech
also need clear line of sight between sender & receiver
subject to many same limitations as infrared
aren’t as susceptible to interference from visible light sources as infrared
what is narrowband radio LAN tech
use low-powered, 2 way radio comm
receiver & transmitter must be tuned to same frequency to handle incoming/outgoing data
need no line of sight between sender & receiver as long as both stay within broadcast range
70m or 230 feet
depending on freq, walls or solid barriers can block signals
interference from other radio sources possible
what is spread spectrum LAN tech
uses multiple freq simultaneously, improving reliability & reducing susceptibility to interference
also makes eavesdropping more difficult
2 main kinds
freq-hopping - switches data between multiple freq at regular intervals
direct-sequence modulation - breaks data into fixed-size segments called chips
transmits data on several diff freq at once
what is the LAN media selection criteria
3 main media choices: UTP, fiber-optic & wireless
bandwidth - higher = more expensive & higher installation costs
if >40gbps, fiber-optic only choice
budget
typical UTP cable installation costs $100 to $200 per cable run
fiber-optic costs twice
wireless has no physical installation costs but need to install access points & verify connectivity
environmental considerations
how electrically noisy?
how important is data security?
more weight factor has, more likely fiber-optic/secured wireless is right choice
span
what dist must network span?
longer spans need fiber-optic or wireless to use between buildings
strategic placement of small switches/hubs give UTP surprising reach
existing cable plant
for upgrade, existing cable plant must be considered
