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Objectives:
1. Define and understand technical terms related to cabling, including
attenuation, crosstalk, shielding, and plenum
2. Identify three major types of network cabling and of wireless network
technologies.
3. Understand baseband and broadband transmission technologies and when to use
each.
4. Decide what kinds of cabling and connections re appropriate for particular
network environments.
5.Describe wireless transmission techniques used in LANs.
6. Describe signaling technologies for mobile computing.
Important Points:
1. When designing network, often wireless will be more cost effective than
wire.
2. Bandwidth - how much data transmitted over a unit of time. Mbits
3. Maximum segment length - distance that signals can be retransmitted and
regenerated correctly.
4. Latency - time it take signal to travel down wire from one end to the other.
5. Insertion Loss - each additional connection adds to the attenuation.
6. Electromagnetic interferences (EMI) from other
broadcast signals fro radio frequency interference (RFI)
7. Cable Grade -Cladding is the sheath material and insulation.
PVC are toxic when burning.
8. Plenum-rated refers to the area between the ceiling and false
ceiling where the cable has to have special insulation usually Teflon.
9. Bend radius - how much the cable can be bent.
10. Baseband use only one channel -digital-- uses entire bandwidth of
cable. Use repeaters
11.Broadband uses an analog signal and amplifiers to deal with segment
length.
12. Mid-split broadband uses a single cable but divides the band width
into two channels each at a different frequency.
13. Dual-cable broadband uses two cables.
14. Coaxial cable - single conductor at the core, metal shielding
(braiding) outer cover sheath
a. Thinnet - 10Base2 - 10Mbits-200 meters RG-58 series
50 ohms impedance. Use BNC connectors - 360 degree bend radius.
b. thicknet - 10Base5 -10Mbits-500 meters - vampire
tap attaches to transceiver use attachment unit - 30 degree bend radius.
interface (AUI).
15. ARCnet - attached resource computing network. 2.5Mbps - 75 ohmn
16. Twisted-pair (TP)- number of twist determine amount of cross
talk. 10BaseT - 100 meters
a. Unshielded TP
1) Cat 1 - voice not
data = phone line into house
2) Cat 2 - 4 pairs wire -
4Mbits
3) Cat 3 - four pairs - 10Mbit
- 16Mhz - 3 twist per foot.
4) Cat 4 - 16 Mbps - 20 Mhz -
datagrade
5) cat 5 - 100 Mbps - 100 Mhz
- four pairs
6) cat 5e - enhanced cat 5 -
7) cat 6 - Gigabps.
downward compatible with cat 5
8) Cat 7 - each wire is
insulated hopefull very high speed.
b. Shielded Twisted -Pair higher band with due to better
insulation.
17. Connectors
a. RJ-45 - eight wires
b. Punch down blocks helps organize cables and permit them to
be arranged.
c. Patch panels permit nearly arbitrary arrangement of
connections.
d. Wall plates receptacles in many office.
e. Jack couplers permit modular cables to stretch between
wall plates.
18. Fiber Optic - photons - eliminates electronic eavesdropping. 1 to 10 Gigabps. May carry as much as 200Gbps.
a. Connectors:
1). Straight tip (ST)-
join individual fibers at interconnects or to optical devices. Like BNC. two
units
2). Straight connection
(SC) push on one unit for both directions
3). Medium interface
connector (MIC) used for the Fiber Distributed Data Interface - one unit.
4). Subminiature type
A (SMA) two units -
5). MT-RJ one
unit very small good
b. single mode cable - one glass fiber
at the core. - laser-based emitters - long distance
c. Multimode cable - two or more glass fibers
at the core - light emitting diodes - shorter distance
d. Cable selection
1). Bandwidth- how much speed
2). Budget - how much money
3). Capacity - how much
traffic
4). Environmental
considerations - how noisy is environment- what about data security.
5). Placement -
6). Scope - how big - #
devices
7). span - distance
8). Local requirement:
building and fire code
9). Existing cable
plant.
19. IBM cabling system designates from 1 to 9 using
American Wire Gauge by diameter of wire. 10 is thick 22
is thinner.
20. Wireless - electro magnetic
a. Hybrid networks - wired and wireless
b. Create temp connections in wired
environment
c. back up contingency for existing
wired network
d. Extend span of network
e. users to roam
f. data for mobile professionals
g. isolated facilities
h. dynamic environments
i. improve customer service
j. network connectivity in building that can
not be altered
k. Home networks
l. Wireless networks
1). LAN - part of
2). Extended LAN
3). Mobile computing
m. Communications carrier - third party vendor
that supplies wireless transmission.
n. Access Pont device includes antenna
and transmitter.
o. Hz - Hertz - cycles per second.
1). Radio: 10 KHz to 1Ghz
2). Microwave 1 Ghz to 500 GHz
3). Infrared 500 GHz to 1 Thz (teraHertz)
p. Four primary technologies
1). Infrared- light beams (100
feet-interference from light)
a) Line
of sight
b)
Reflective wireless networks - goes to central hub for
distribution
c) Scatter
infrared networks - bounce off wall and ceilings. (30 meters)
d)
Broadband optical telepoint networks - high speed and wide bandwidth.
2). Laser- line of sight - no
interference from light
3). Narrowband, single-frequency
radio- no line of sight-70 meters
4). Spread-spectrum radio-
multiple frequency-frequency hopping
a) Direct
sequence modulation -breaks data into chips (packet) and transmits over
several frequencies at once. fouls ease dropping.
q. 802.11 Wireless Networking- 5 to 300 ft.
1). 802.11a - 54 mbps - 5Ghz
2). 802.11b - 11 mbps -2.4 GHz
3). 802.11g - 54 mbps - 2.4
ghz - backward compatible with 802.11b
r. Wireless bridges can connect networks up to
three miles. Work in pairs like repeaters.
s. Microwave - high transmission rates - line of
sight
1). Terrestrial microwave -
tight beam high frequency - towers
2). Geosynchronous satellites
- 50 k meters (23,000 miles) Global reach.
t. Cellular packet radio - 2mps range of broadcast
u. Cellular digital packet data (CDPD) - 19.2kbps -
handheld and palmtop pda.
v. narrow-band sockets - communicate with internet -
pagers, cell phones, wireless computers.
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