Cabling & Topology Flashcards
bus topology
uses a single cable (the bus) that connects all computers in a line
data from each computer goes out on entire bus
needs termination to prevent reflection from bringing down the network
single break - network down
ring topology
connects all computers with a ring of cable
data moves from 1 computer to the next in the same direction
no need for termination
single break - network down
star topology
uses a central connection box for all computers on the network
fault tolerance - 1 connection can be interrupted without affecting others
hybrid topology
any topology that combines a physical & (signaling) logical topology
physical topology
how cables appear physically in topology
signaling (logical) topology
how signals travel electrically in topology
2 topologies used in almost all wireless networks
mesh
point-to-multipoint
mesh topology
every computer connects to every other computer via 2 or more routes
fully meshed = every computer connects directly with ever other computer
partially meshed = at least 2 machines have redundant connections
point-to-multipoint topology
single system acts as a common source through which all members of network communicate
differs from star - central box is intelligent device
point-to-point topology
2 computers connected directly with no need for central device
wired or wireless
network technology
practical application of a topology & other critical technologies that provide a method to get data from 1 computer to another on a network
2 primary types of copper wiring
twisted pair
coaxial
coaxial cable
contains a conductor wire (usually copper) surrounded by a braided metal shield
radio grade (RG) rating
coaxial connector
F-connector
screws on to threaded port
cable modems connect with [blank] coax cable
RG-6
RG-59 (rarely, Cable TV)
Ohm rating
relative measure of the resistance on the cable
RG-6 & RG-59 rated at 75 Ohms
coax cables split with [ 1 ] joined with [ 2 ]
1 - splitter
2 - barrel connector
UTP twist benefit
reduces crosstalk
more twists = less crosstalk
shielded twisted pair (STP)
twisted pairs surrounded by shielding to protect wires from EMI
rare - excessive electronic noise
unshielded twisted pair (UTP)
twisted pairs surrounded by plastic jacket
no EMI protection
by far most popular modern cable
category (CAT) ratings
rating in megahertz (MHz) indicating highest frequency a cable can handle
used to select correct cable for the technology
frequency of CAT ratings
number of cycles per second
bandwidth
maximum amount of data that can move through a cable per second
bandwidth - efficiency encoding schemes
maximizing bits into a signal as long as the cable can handle it
UTP connectors
RJ-45 (4 pairs | networks)
RJ-11 (2 pairs | phones)
fiber-optic core
glass fiber
fiber-optic cladding
part that makes light reflect down the fiber
fiber-optic buffer
material used to give cable strength
fiber-optic cable
transmits light rather than energy
speed, distance, EMI resistance
core, cladding, buffer, insulating jacket
fiber-optic cable sizing
different diameter core & cladding
2 number designator - measured in micrometers
62.5/125 is most common size
fiber light transmission
regular light or laser
each require different type of cable
fiber network installation requirements
pairs of fiber cables
1 to send - 1 to receive
duplex fiber cabling combines cables in 1 jacket
MMF
multimode fiber
fiber-optic cable that uses LED to send signals
most common
SMF
single-mode fiber
fiber-optic cable that uses lasers to send signals
benefit of SMF over MMF
no modal distortion
modal distortion
signals sent at the same time don’t arrive at the same time
signals differ slightly in length
fiber-optic signal wavelengths
MMF - 850 nm
SMF - 1310 or 1550 nm
fiber-optic connectors
ST - single, round, snap / twist
SC - single, square
LC - duplex, square
MT-RJ - duplex, square, slim
classic serial cables
predates networking & PC
RS-232 - recommended standard upon which all serial communication takes place
slow connection speeds (56,000 bps)
only point-to-point
serial connectors
9-pin - male D-subminiature (DB-9)
most common
parallel cables
as old as serial cables
only point-to-point
up to 2 Mbps (much slower for networking)
parallel connectors
25-pin female DB (DB-25)
fire ratings - PVC
polyvinyl chloride
no significant fire protection
produces a lot of smoke & toxic fumes
fire ratings - plenum
creates much less smoke & fumes
more expensive
usually required by ordinance
standards defined by 802 committee
frames
speeds
distances
type of cabling
IEEE 802.3
Ethernet
lots of subcommittees
IEEE 802.11
Wireless LAN (WLAN)
specifications i.e. WiFi
many subcomittees
CAT 3
16 MHz
16 Mbps
CAT 5
100 MHz
100 Mbps
CAT 5e
100 MHz
1,000 Mbps
CAT 6
250 MHz
10,000 Mbps
100 m in 10/100/1000BaseT networks
55 m in 10GBaseT networks
CAT 6a
500 MHz
10,000 Mbps
100 m in 10GBase T
