Topic 3.1 data transmission and networking media

Learning Outcomes
1. Describe the physical characteristic of
coaxial cable, STP, UTP and fiber
optic media.
2. Describe the wireless transmission.

The Internet Cloud
• The Internet can be thought of as a network of routers,
interconnected with one another. Very often, there are
alternate routes between routers, and packets may
take different paths between source and destination.

Common Network Cables
• In order for communication to occur a source,
destination, and some sort of channel must be
present. A channel, or medium, provides a
path over which the information is sent.
• The medium is usually some sort of physical
cable. It may also be electromagnetic
radiation, in the case of wireless networking.

Common Network Cables - continue
• There are two kinds of physical cable.
– Metal cables, usually copper, have electrical
impulses applied to them to convey
information.
– Fiber optic cables, made of glass or plastic,
use flashes of light to convey information.

Types of Cables Used in Networking
• Common types of cables

TWISTED PAIR CABLE
• UTP
• STP
• ScTP

TWISTED PAIR CABLE
 Twisted pair uses pulses of electricity to transmit
data.
 Data transmission is sensitive to interference or
noise, which can reduce the data rate that a
cable can provide. A twisted pair cable is
susceptible to electromagnetic interference
(EMI).
 When data transmission is corrupted due to
interference, the data must be retransmitted.
This can degrade the data carrying capacity of
the medium.

TWISTED PAIR CABLE - continue
 In twisted pair cabling, the number of twists per
unit length affects the amount of resistance that
the cable has to interference.
 Twisted pair cable suitable for carrying
telephone traffic, referred to as CAT3, has 3-4
turns per foot making it less resistant.
 Cable suitable for data transmission, known as
CAT5, has 3-4 turns per inch, making it more
resistant to interference.

How data transmission effected by interference.

There are 3 types of twisted pair cable:
– unshielded twisted pair (UTP),
– shielded twisted pair (STP),
– screened twisted pair (ScTP).

Unshielded Twisted Pair (UTP)
 UTP cable is inexpensive, offers a high bandwidth, and
is easy to install.
 This type of cable is used to connect workstations,
hosts and network devices.
 Each category of cable was developed to support a
specific technology. The cable types which are still
commonly found include Categories 3, 5, 5e and 6.
 All Categories of data grade UTP cable are traditionally
terminated into an RJ-45 connector.

Shielded Twisted Pair (STP) & Screened
Twisted Pair (ScTP)
 There are electrical environments in which EMI and RFI
are so strong that shielding is a requirement to make
communication possible, such as in a noisy factory.
 In this instance, it may be necessary to use a cable that
contains shielding, such as Shielded twisted-pair (STP)
and Screened twisted-pair (ScTP).
 But both STP and ScTP are very expensive, not as
flexible, and have additional requirements due to the
shielding that make them difficult to work with.

CABLE CATEGORIES
 used for voice communication, often used for
phone lines.
 used for data transmission, individual pair are
wrapped in a shield and the entire four pairs
wrapped in another shield. Support
1000Mbps to 10Gbps (not recommended)
 used for data transmission, an added
separator is between each pair of wires
allowing it to function at higher speeds.
Support 1000Mbps to 10Gbps (not
recommended)
 used for data transmission, Cat 5 support
100Mbps to 10Gbps. Cat 5e support
1000Mbps.

UNSHILDED TWISTED PAIR
(UTP) CABLING

UTP CABLE
• Twisted pair cable is most commonly used in
network installations.
• The TIA/EIA organization defines two different
patterns, or wiring schemes, called T568A and
T568B.
• Each wiring scheme defines the pin out, or order
of wire connections, on the end of the cable.

UTP CABLE - continue
• On a network installation, one of the two wiring schemes
(T568A or T568B) should be chosen and followed.

Using the T568A and T568B wiring schemes, two
types of cables can be created: Straight-Thru and
Crossed-Over

Straight-through Cables
• If T568A is on one end of the cable, T568A is
also on the other. If T568B is on one end of the
cable, T568B is on the other.
• This means that the order of connections (the
pin out) for each color is the exact same on both
ends.

Crossover Cable
• A crossover cable uses both wiring schemes.
• T568A on one end of the cable and T568B on the other
end of the same cable.
• This means that the order of connection on one end of
the cable does not match the order of connections on
the other.
• The type of cable needed to connect two devices
depends on which wire pairs the devices use to
transmit and receive data.

CAT5 Wiring Standard
Pin# Signal EIA/TIA 568A EIA/TIA 568B
1 Transmit+ White/Green White/Orange
2 Transmit- Green Orange
3 Receive+ White/Orange White/Green
4 N/A Blue Blue
5 N/A White/Blue White/Blue
6 Receive- Orange Green
7 N/A White/Brown White/Brown
8 N/A Brown Brown

Color Code: Straight Thru T-568A
PC SWITCH

Color Code: Straight Thru T-568B
PC SWITCH

Color Code: Crossover Cable
PC PC

Construct and Terminate Twisted Pair
Cables – RJ-45 Connector
• UTP and STP cable is usually terminated into
an RJ-45 connector.
• With the metal contacts facing up, the pin
locations are numbered from 8 on the left to 1
on the right.

SHILDED TWISTED PAIR
(STP) CABLING

SCREENED TWISTED PAIR
(ScTP) CABLING

Parts of Coaxial Cable
Four main parts:
• Copper conductor
• Plastic insulation
• Braided copper shielding
• Outer jacket
Coaxial cable is used as a transmission line for radio
frequency signals

Coaxial Cable
Coax is no longer used, but it has several
advantages:
• Can run for longer distances without need for repeaters
• Less expensive than fiber-optic cable, although more
expensive than UTP and STP

FIBER OPTIC
• Single Mode
• Multi Mode

• Fiber optic cables are made of glass or plastic, neither of
which conducts electricity.
• They have a very high bandwidth, which enables them
to carry very large amounts of data. It carry digital
information at very high speed over long distance.
• Fiber is used in backbone networks, large enterprise
environments and large data centers and are also used
to connect ISPs on the Internet. It is also used
extensively by telephone companies.
Fiber Optic

FIBER OPTIC - continue
• Unlike twisted pair and coaxial, fiber optic cables
transmit data using pulses of light, electrical interface
does not affect the signal.
• Although not normally found in home or small business
environments, fiber optic cabling is widely used in
enterprise environments and large data centers.

• Jacket
– Added to protect the fiber against abrasion, solvents,
and other contaminants, the composition may vary
depend on the cable usage.
• Strengthening material
– Surround the buffer, prevents the fiber cable from
being stretched when it is being pulled. The material
used is often the same material used to produce
bulletproof vests.
• Buffer
– Used to help shield the core and cladding from
damage.

• Cladding
– Made from slightly different chemicals than those
used to create core. It tends to act like a mirror by
reflecting light back into the core of the fiber. This
keeps light in the core as it travels down the fiber.
• Core
– The core is actually the light transmission element at
the center of the optical fiber.
– This core typically silica or glass.
– Light pulses travelling through the fiber core.

• There are two forms of fiber optic cable:
multimode and single mode.
• Multimode
– Multimode is the less expensive and more widely used.
The light source that produces the pulses of light is usually
an LED.
– It is referred to as multimode because there are multiple
rays of light, each carrying data, being transmitted through
the cable simultaneously. Each ray of light takes a
separate path through the multimode core.
– Multimode fiber optical cables are generally suitable for
links of up to 2000 meters.

• Single Mode
– Single mode fiber optic cables are constructed in such a
way that light can follow only a single path through the
fiber.
– The light source for single mode fiber optic cables is
usually a LED laser, which is significantly more expensive
and intense than ordinary LEDs. Due to the intensity of the
LED laser, much higher data rates and longer ranges can
be obtained.
– Single mode fibers can transmit data for approximately
3000 meters and are used for backbone cabling.

Wireless Media
• Electricity cannot pass through the air, so a
conductor like a copper wire is required
• Infrared energy can go through the air, but it
doesn’t pass through solid objects well
• Wireless media does not use wire or cable of
any kind; it sends data using radio waves

Enterprise WLAN Components and
Design
To create a wireless LAN, these components
are required:
• PCs with WLAN NICs
• Access Points (APs), which act as a LAN hub for
wireless devices

Enterprise WLAN Components and Design:
Wireless NIC and Access Point (AP)

Typical Enterprise WLAN Design

WLAN Organizations and Standards
• The IEEE defines WLAN standards as part of the
802.11 committee
• The most common WLAN standards are 802.11a,
802.11b, and 802.11g + ???
• All devices must comply with rules concerning radio
transmission - in the US, the Federal
Communications Commission sets the standards

I don’t stop when I’m tired.
I only stop when I’m done…

Class Exercise
• List 4 type of wired media (4 m)
Utp,stp,coaxial,fiber optic
• List 2 device of wireless media (2 m)
Modem,nic wireless,access point
• List two form/mode of data
transmission in fiber optic (2m)
Single mode, Multimode
• List 5 part in fiber optic cable (5m)
Jacket, Strengthening material, buffer
Cladding, core

Topic 3.1 data transmission and networking media

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