CEN-444
Networks Structure And Protocols
Transmission Medium
Mohammed Saleem Bhat
m.bhat@mu.edu.sa
Computer Engineering and Networks, College of Engineering , Majmaah University
PHYSICAL MEDIA
Computer Engineering and Networks, College of Engineering , Majmaah University
Physical Media
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Physical Media
Copper
Coaxial Cable - Thick or Thin
Unshielded Twisted Pair - CAT 3,4,5,5e&6
Optical Fiber
Multimode
Singlemode
Wireless
Short Range
Medium Range (Line of Sight)
Satellite
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Copper Media: Coaxial Cable
Coaxial cable is a coppercored cable surrounded by a
heavy shielding and is used
to connect computers in a
network.
Outer conductor shields the
inner
conductor
from
picking up stray signal from
the air.
High bandwidth but lossy
channel.
Repeater
regenerate
signals.
is
used
to
the weakened
Category
Impedance
Use
RG-59
75 W
Cable TV
RG-58
50 W
Thin
Ethernet
RG-11
50 W
Thick
Ethernet
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Copper Media: Twisted Pair
Twisted-pair is a type of cabling
that is used for telephone
communications
and
most
modern Ethernet networks.
A pair of wires forms a circuit
that can transmit data. The
pairs are twisted to provide
protection against crosstalk, the
noise generated by adjacent
pairs.
There are two basic types,
shielded twisted-pair (STP) and
unshielded twisted-pair (UTP).
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Shielded Twisted Pair (STP)
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Unshielded Twisted Pair (UTP)
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Unshielded Twisted Pair (UTP)
Consists of 4 pairs (8 wires) of insulated
copper wires typically about 1 mm thick.
The wires are twisted together in a helical
form.
Twisting reduces the
between pairs of wires.
interference
High bandwidth and High attenuation
channel.
Flexible and cheap cable.
Category rating based on number of
twists per inch and the material used
CAT 3, CAT 4, CAT 5, Enhanced CAT 5
and now CAT 6.
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Categories of UTP
UTP comes in several categories that are based on the
number of twists in the wires, the diameter of the wires
and the material used in the wires.
Category 3 is the wiring used primarily for telephone
connections.
Category 5e and Category 6 are currently the most
common Ethernet cables used.
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Categories of UTP: CAT 3
Bandwidth 16 Mhz
11.5 dB Attenuation
100 ohms Impedance
Used in voice applications and 10baseT (10Mbps) Ethernet
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Categories of UTP: CAT 4
20 MHz Bandwidth
7.5 dB Attenuation
100 ohms Impedance
Used in 10baseT (10Mbps) Ethernet
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Categories of UTP: CAT 5
100 MHz Bandwidth
24.0 dB Attenuation
100 ohms Impedance
Used for high-speed data transmission
Used in 10BaseT (10 Mbps) Ethernet & Fast Ethernet (100
Mbps)
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Categories of UTP: CAT 5e
150 MHz Bandwidth
24.0 dB Attenuation
100 ohms Impedance
Transmits high-speed data
Used in Fast Ethernet (100 Mbps), Gigabit Ethernet (1000
Mbps) & 155 Mbps ATM
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Categories of UTP: CAT 6
250 MHz Bandwidth
19.8 dB Attenuation
100 ohms Impedance
Transmits high-speed data
Used in Gigabit Ethernet (1000 Mbps) & 10 Gig Ethernet
(10000 Mbps)
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Fiber Media
Optical fibers use light to
send information through
the optical medium.
It uses the principal of
total internal reflection.
Modulated
light
transmissions are used to
transmit the signal.
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Total Internal Reflection
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Fiber Media
Light travels through the optical media by the way of total
internal reflection.
Modulation scheme used is intensity modulation.
Two types of Fiber media :
Multimode
Singlemode
Multimode Fiber can support less bandwidth than
Singlemode Fiber.
Singlemode Fiber has a very small core and carry only one
beam of light. It can support Gbps data rates over > 100
Km without using repeaters.
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Single and Multimode Fiber
Single-mode fiber
Carries light pulses
along single path
Uses Laser Light Source
Multimode fiber
Many pulses of light
generated by LED travel
at different angles
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Fiber Media
The bandwidth of the fiber is limited due to the dispersion
effect.
Distance Bandwidth product of a fiber is almost a
constant.
Fiber optic cables consist of multiple fibers packed inside
protective covering.
62.5/125 µm (850/1310 nm) multimode fiber
50/125 µm (850/1310 nm) multimode fiber
10 µm (1310 nm) single-mode fiber
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Fiber-Optic Cable
Contains one or several
glass fibers at its core
Surrounding the fibers is a
layer called cladding
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Fiber Optic Cable
FO Cable may have 1 to
over 1000 fibers
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Wireless Media
Very useful in difficult
terrain where cable laying
is not possible.
Provides
mobility
to
communication nodes.
Right of way and cable
laying costs can be
reduced.
Susceptible
to
rain,
atmospheric
variations
and
Objects
in
transmission path.
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Wireless Media
Indoor : 10 – 50m : BlueTooth, WLAN
Short range Outdoor : 50 – 200m: WLAN
Mid Range Outdoor : 200m – 5 Km : GSM, CDMA,
WLAN Point-to-Point, Wi-Max
Long Range Outdoor : 5 Km – 100 Km : Microwave
Point-to-Point
Long Distance Communication : Across Continents :
Satellite Communication
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Frequency Bands
Band
Range
Propagatio
n
Application
VLF
3–30 KHz
Ground
Long-range radio navigation
LF
30–300 KHz
Ground
Radio beacons and
navigational locators
MF
300 KHz–3 MHz
Sky
AM radio
HF
3–30 MHz
Sky
Citizens band (CB),
ship/aircraft communication
VHF
30–300 MHz
Sky and
line-of-sight
VHF TV,
FM radio
UHF
300 MHz–3 GHz
Line-ofsight
UHF TV, cellular phones,
paging, satellite
SHF
3–30 GHz
Line-ofsight
Satellite communication
Line-ofEHF
30–300 GHz
Long-range radio navigation
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sight
Wireless LAN
PC
Access Point
Internet
Router
Switch
PC
Access Point
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Terrestrial Microwave
Microwaves do not follow
the curvature of earth
Line-of-Sight
transmission
Height allows the signal to
travel farther
Two frequencies for two
way communication
Repeater is used to
increase the distance Hopby-Hop
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Satellite Communication
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UTP AND FIBER CABLING
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Structured Cabling Infrastructure
Mounted and permanent
Allows patching
Comfort that infrastructure is
OK
Components:
Information Outlet with Face
Plate
Patch Panel
UTP Cable
Patch Cord
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I/O & Faceplates
Faceplate mounts on or in
wall or in raceway
Single or Dual Information
Outlet (I/O)
Provide
network
connectivity to the Hosts
through a Patch Cord
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Patch Panel
Termination punchdown
in back
Patch cord plugin in front
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Patch Cord & UTP Connectors
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Color Codes
Data Tx: 1 & 2
Data Rx: 3 & 6
Crossover
13
26
PoE +VDC: 4 & 5
PoE -VDC: 7 & 8
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Cutting, Striping & Crimping Tools
Make your own patch cords
Cuts and strips pairs
RJ45 end crimped onto ends of
wire
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Punching Tool
Terminates wires to back of
patch
panels
and
in
Information Outlets
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Making Cables
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Wire Testing Equipment
Test wire for correct
termination of 8 wires
Test for speed capabilities
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Cabling Rules
Try to avoid running cables parallel to power cables.
Do not bend cables to less than four times the diameter of the cable.
If you bundle a group of cables together with cable ties (zip ties), do
not over-cinch them. You should be able to turn the tie with fingers.
Keep cables away from devices which can introduce noise into
them. Here's a short list: copy machines, electric heaters, speakers,
printers, TV sets, fluorescent lights, copiers, welding machines,
microwave ovens, telephones, fans, elevators, motors, electric ovens,
dryers, washing machines, and shop equipment.
Avoid stretching UTP cables (tension when pulling cables should not
exceed 25 LBS).
Do not run UTP cable outside of a building. It presents a very
dangerous lightning hazard!
Do not use a stapler to secure UTP cables. Use telephone wire/RJ6
coaxial wire hangers which are available at most hardware stores.
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Fiber Optic Cabling Infrastructure
Components:
Fiber Cable
Fiber Pigtail
Fiber Connectors
LIU
Coupler
Fiber Patch Cord
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Fiber Optic Connectors
Terminates the fibers
Connects to other fibers or
transmission equipment
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Fiber Patch Cords & Pigtails
Ends are typically either
SC or ST
Pigtails have connectors
on only one side and
Patch Cords have it on
both sides.
Pigtails are spliced to the
fiber to terminate the
fiber
Patch
Cord
connects
switches to the Fiber cable
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LIU & Couplers
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Fiber Optic Installation –
Outside Plant
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Fiber Optic Installation –
Outside Plant
Fiber is blown in HDPE
Pipes, 1 m deep.
The HDPE pipes is
covered with sand and
brick lining
Fiber Roles are typically 2
Km. Fiber cables are
spliced using Jointers
Faults like fiber cut are
located
using
OTDR
(Optical Time Domain
Reflectometer)
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LAN TECHNOLOGIES
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Technology Options
Ethernet
Fast Ethernet
Gigabit Ethernet
10 Gig Ethernet
WLAN
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Media Access
Ethernet and Wi-Fi are both “multi-access” technologies
Broadcast medium, shared by many hosts
Simultaneous transmissions will result in collisions
Media Access Control (MAC) protocol required
Rules on how to share medium
The Data Link Layer is divided into two Part MAC Media
Access Control) Sublayer and LLC (Logic Link Control)
Sublayer
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802.3 Ethernet
Carrier-sense multiple access with collision detection
(CSMA/CD).
CS = carrier sense
MA = multiple access
CD = collision detection
Base Ethernet standard is 10 Mbps.
100Mbps, 1Gbps, 10Gbps standards came later
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Ethernet CSMA/CD
CSMA/CD (carrier sense multiple access with collision
detection) media access protocol is used.
Data is transmitted in the form of packets.
Sense channel prior to actual packet transmission.
Transmit packet only if channel is sensed idle; else,
defer the transmission until channel becomes idle.
After packet transmission is started, the node monitors
its own transmission to see if the packet has
experienced a collision.
If the packet is observed to be undergoing a collision,
the transmission is aborted and the packet is
retransmitted after a random interval of time using
Binary Exponential Backoff algorithm.
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Ethernet Address
End nodes are identified by their Ethernet Addresses
(MAC Address or Hardware Address) which is a unique 6
Byte address.
MAC Address is represented in Hexa Decimal format e.g
00:05:5D:FE:10:0A
The first 3 bytes identify a vendor (also called prefix) and
the last 3 bytes are unique for every host or device
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Ethernet Frame Structure
Preamble:
7 bytes with pattern 10101010 followed by one byte with
pattern 10101011
Used to synchronize receiver, sender clock rates
Addresses: 6 bytes, frame is received by all adapters on a
LAN and dropped if address does not match
Length: 2 bytes, length of Data field
CRC: 4 bytes generated using CR-32, checked at receiver, if
error is detected, the frame is simply dropped
Data Payload: Maximum 1500 bytes, minimum 46 bytes
If data is less than 46 bytes, pad with zeros to 46 bytes
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Ethernet
10 Base 5 (Thicknet) (Bus Topology)
10 Base 2 (Thinnet) (Bus Topology)
10 Base T (UTP) (Star/Tree Topology)
10 Base FL (Fiber) (Star/Tree Topology)
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Ethernet BUS Topology
Repeater
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Ethernet STAR Topology
Hub
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Ethernet
Physical Media :10 Base5
10 Base2
10 BaseT
10 BaseFL
-
Thick Co-axial Cable with Bus Topology
Thin Co-axial Cable with Bus Topology
UTP Cat 3/5 with Tree Topology
Multimode/Singlemode Fiber with Tree
Topology
Maximum Segment Length
10 Base5 - 500 m with at most 4 repeaters (Use Bridge to extend
the network)
10 Base2 - 185 m with at most 4 repeaters (Use Bridge to extend
the network)
10 BaseT - 100 m with at most 4 hubs (Use Switch to extend the
network)
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Fast Ethernet
100 Mbps bandwidth
Uses same CSMA/CD media access protocol and packet
format as in Ethernet.
100BaseTX (UTP) and 100BaseFX (Fiber) standards
Physical media :100 BaseTX - UTP Cat 5e
100 BaseFX - Multimode / Singlemode Fiber
Full Duplex/Half Duplex operations.
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Fast Ethernet
Provision for Auto-Negotiation of media speed:
10 Mbps or 100Mbps (popularly available for copper
media only).
Maximum Segment Length
100 Base TX - 100 m
100 Base FX - 2 Km (Multimode Fiber)
100 Base FX - 20 km (Singlemode Fiber)
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Gigabit Ethernet
1 Gbps bandwidth.
Uses same CSMA/CD media access protocol as in Ethernet
and is backward compatible (10/100/100 modules are
available).
1000BaseT (UTP), 1000BaseSX (Multimode Fiber) and
1000BaseLX (Multimode/Singlemode Fiber) standards.
Maximum Segment Length
1000 Base T
- 100m (Cat 5e/6)
1000 Base SX - 275 m (Multimode Fiber)
1000 Base LX - 512 m (Multimode Fiber)
1000 Base LX - 20 Km (Singlemode Fiber)
1000 Base LH - 80 Km (Singlemode Fiber)
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10 Gig Ethernet
10 Gbps bandwidth.
Uses same CSMA/CD media access protocol as in
Ethernet.
Propositioned for Metro-Ethernet
Maximum Segment Length
1000 Base-T
- Not available
10GBase-LR
- 10 Km (Singlemode Fiber)
10GBase-ER
- 40 Km (Singlemode Fiber)
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