Network Hardware and Physical
Media
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Network hardware
includes:
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Computers
Peripherals
Interface cards and
Other equipment needed
to perform data
processing and
communications within
the network
File servers
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A very fast computer
with a large amount of
RAM and storage space
along with a fast
network interface card
The network operating
system software resides
on this computer
Workstations
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All computers
connected to the file
server on a network are
called workstations
Network interface cards
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The network interface card
(NIC) provides the physical
connection between the network
and the computer workstation.
Most NICs are internal with the
card fitting into an expansion
slot in the computer.
Three common network
interface connections are
Ethernet cards, Local Talk
connectors and Token Ring
cards
Ethernet cards
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The most common
Network Interface
Cards are Ethernet
cards
They contain
connections for either
coaxial or twisted pair
cables, or both
Co-axial
cable
Twisted
pair cable
Concentrators / Hubs
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A concentrator is a
device that provides a
central connection point
for cables from
workstations, servers
and peripherals
Hubs are multi-slot
concentrators
Switches
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hubs provide an easy way to
scale up and shorten the
distance that the packets must
travel to get from one node to
another
they do not break up the actual
network into discrete segments.
That is where switches come in.
Switches (continued)
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A vital difference between a hub and a switch is
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all the nodes connected to a hub share the bandwidth among themselves.
while a device connected to a switch port has the full bandwidth all to itself.
Think of a switch as a ‘clever’ hub
Repeaters
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A signal loses strength as it passes along a
cable, so it is often necessary to boost the
signal with a device called a repeater
A repeater might be a separate device, or
might be part of a concentrator
Bridges
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A bridge is a device that allows you to
segment a large network into two
smaller, more efficient networks
An example of a network with a bridge
Router
Hub
Bridge
Hub
Internet
Segment
Node
Routers
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A router translates information from one network to
another
The router directs traffic to prevent “head-on”
collisions
If you have a LAN that you want to connect to the
Internet, you will need a router to serve as the
translator between information on your LAN and the
Internet
Routers (continued)
Physical Media
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Physical media provide the connections
between network devices that make
networking possible
There are four main types of physical media
in widespread use today:
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Coaxial Cable
Twisted Pair
Fiber Optic Cable
Wireless Media
LAN Technologies
Ethernet
Physical Media :10 Base5
10 Base2
10 BaseT
10 BaseFL
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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
10 Base2
10 BaseT
- 500 m with at most 4 repeaters (Use Bridge to extend
the network)
- 185 m with at most 4 repeaters (Use Bridge to extend
the network)
- 100 m with at most 4 hubs (Use Switch to extend the
network)
Thick Coaxial Cable
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Used in the first Ethernet networks
Type RG-11 / 10Base5
Usually orange/black
Thickness of a small garden hose
Very expensive and heavy cable
Two strands along the axis
Conductor down the center
Insulator surrounds conductor
Shielded mesh serves as outside
Thin Coaxial Cable
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Alternative to Thick Ethernet Cable
Type RG-58 / 10Base2 / “Cheapnet”
Usually black
Thickness of a pencil
More flexible than thick Ethernet
Reduced the cost of the cabling
Flexible
Coaxial cable connectors
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The most common type of connector used
with coaxial cables is the BNC connector
Twisted Pair Cable
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Phone Systems
Twisted Pair Cable consists of two copper
wires, usually twisted around each other to
cancel out any noise in the circuit
Two main type of Twisted Pair Cabling
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Shielded Twisted Pair (STP)
Unshielded Twisted Pair (UTP)
Shielded Twisted Pair (STP)
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STP is the original media used for token ring networks
STP can be used for high-speed networks, such as FDDI or ATM,
where shielding is important.
RJ-45
Unshielded Twisted Pair (UTP)
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UTP has four pairs of wires inside the jacket
Each pair is twisted with a different number of twists per
inch to help eliminate interference from adjacent pairs
UTP (Continued)
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Most commonly used twisted pair cable
Uses common telephone wire
UTP was standardized by the IEEE 802.3
committee in October of 1990
UTP for LANs is now classified as:
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Category 3 - used for LANs up to 10 Mbps
Category 4 - used for LANs up to 16 Mbps
Category 5 - used for LANs up to 100 Mbps
Fiber Optic Cable
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Fiber optic cabling consists of a center glass core
surrounded by several layers of protective materials
It transmits light rather than electronic signals
It is the standard for connecting networks between
buildings, due to its immunity to the effects of moisture
and light
Fiber Optic (continued)
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Fiber optic cable has the ability to transmit signals over
much longer distances than coaxial or twisted pair
It can also carry information at vastly greater speeds
Fiber optic cable is more difficult to install than other
cabling
Wireless LANS
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Wireless networks use high frequency radio signals to
communicate between the workstations and the fileserver or
hubs.
Disadvantages of wireless networks are:
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they are expensive (relatively),
provide poor security,
are susceptible to interference and
are slower than cabled networks