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
