Download MCSE Guide to Designing a Windows 2000 Directory Service

Computer Networks
Done By:
Sulaiman Qeshta
Ahmed Faris
Ahmed Al-Abadelah
Jehad Tabash
Huseen Abu Yousif
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Objectives
 Learning about:
• Networks and its benefits
• Types of Networks
• Network Technologies
• Topologies
• Network Devices
• Networks Cabling
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Networks
Computers connect to each other via cable to share
resources
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Use of Computer Networks
 Networks for Companies:
•
•
•
•
Resource sharing
High reliability
Saving money
Using client-server model
 Networks for People:
• Access to remote information.
• Person-to-person communication.
• Interactive entertainment.
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Types of Networks
There are basically two types of networks:
Local-area networks (LAN): ( 10 m - 1km )
LAN are usually designed to cover a small geographical
area and are generally used in an office environment.
Wide-area network (WAN): ( over 100km )
WAN are usually distributed over a large geographical
area (such as the United States).
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Network Technologies

Point-to-Point Technology
 Connections between
individual pairs of
machines.
 Message may pass
through many pairs of
point-to-point connections
to get from source to
destination.
 Often machines may have
multiple point-to-point
connections.
 Large (geographically)
networks.
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Network Technologies (continue…)
 Broadcast Technology
A single channel is shared by all the machines on the
network (nodes or stations).
 Messages sent by one node are received by all.
 Use Address field in message to specify target of.
 Special address to send to all/subset of the stations
(broadcast/multicast).
 Usually small (geographically) networks.
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Topologies
There are two kinds of Topologies:
 The physical topology of a network refers to the
configuration of cables, computers, and other peripherals.
 The Logical topology is the method that used to
pass the information.
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Break
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Topologies ( continue… )
Main types of physical topologies :
 Star brunch from hub.
 Ring or loop.
 Bus or row. linear bus
 Tree .
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Star Networks:
•
•
•
•
A network with radial topology in which a central the
point to which all other nodes join.
Signals are transmitted from the sending computer
through the central node to all computers on the
network.
Its centralized resources and management. However,
because each computer is connected to a central
point, this topology requires a great deal of cable in a
large network installation.
if the central point fails, the entire network goes down.
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Star Networks: ( continue…)
Advantages of a star topology:
• Easy to install and wire.
• No disruptions to the network
connecting or removing devices.
• Easy to detect faults and to remove parts.
Disadvantages of a star topology:
• Requires more cable length than a linear
topology.
• If the hub or concentrator fails, nodes
attached are disabled.
• More expensive than linear bus topologies
because of the cost of the concentrators.
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Ring Networks:
Ring architecture connects each node in a
closed loop, Signals ravel from one node to
the next in a single direction around the
loop.
Advantages of a ring topology:• It is more scalable because the point-to-point
links between nodes dose not limit the
number of nodes in the ring.
Point-to-point: - A direct link between two
objects in a network.
Disadvantages of a ring topology:• A failure of any link between a node pair
takes the bus down
and prevents communication by other nodes.
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Linear Bus:
•
•
A linear bus topology consists of
a main run of cable with a
terminator at each end.
To understand how computer
communication on bus you need
to be familiar with three
concepts:
• Sending the signal
• Signal bounce
• The terminator
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Linear Bus: (continue…)
Advantage of a linear bus topology:
 Easy to connect computer or peripheral to a linear bus.
 Requires less cable length than star topology.
 The bus is simple, reliable in very small networks, easy to use, and
easy to understand.
 The bus requires the least amount of cable to connect the
computers together and is therefore less expensive than other
cabling arrangement.
 It is easy to extend a bus.
Disadvantages of a linear bus topology:
 Entire network shuts down if there is a break in the main cable.
 It difficult to troubleshoot the bus.
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Tree Topology:
•
•
•
A tree topology combines characteristics of linear bus and
star topologies.
It consists of groups of star- configured workstation
connected to a linear but backbone cable.
Tree topologies allow for the expansion of an existing
network, and enable schools to configure a network to
meet their needs.
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Tree Topology: ( continue…)
Advantages of a tree topology:
 point-to point wiring for individual segments.
 Supported by several hardware and software venders.
Disadvantages of a tree topology:
•
•
•
Overall length of each segment is limited by the type of
cabling used.
If the backbone line breaks, the entire segment goes down.
More difficult to configure and wire than other topologies.
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Parts of a Networks:
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•
•
•
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Servers: Provide shared resources to users
Clients: Use the shared resources from servers
Media: Device for connection
Shared peripherals: Resources provided by servers
such as printers, modems
Shared resources: Files, graphics.
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Break
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Network Devices:
Network Devices
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Network Devices:
 Repeaters
• Used to connect together two or more Ethernet
segments
• Various media types
• Signal quality begins to deteriorate as segments
exceed their maximum length
 Hubs
• Signal amplification required to allow a segment to
be extended a greater distance
• Ethernet hubs are necessary in star topologies
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Network Devices: (continue…)
 Switches
• Expansion of the concept in Ethernet bridging
• Link multiple networks together
• Two basic architectures
– Cut-through examines the packet destination address
only before forwarding it on to its destination segment
– Store-and-forward switch accepts and analyzes the
entire packet before forwarding it to its destination.
• Level-3 Switch has IP routing capabilities
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Network Devices: (continue…)
 Bridges
• Connect separate networks together
– Different networks types (such as Ethernet and
Fast Ethernet)
– Networks of the same type
• Bridges map the Ethernet addresses of the nodes
residing on each network segment
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Network Devices: (continue…)
•
Bridges: (continue…)
• Allow only necessary traffic to pass through the
bridge
– Bridge determines the destination and source
segments
– If the segments are the same, the packet is
dropped ("filtered"); if the segments are different,
then the packet is "forwarded" to the correct
segment.
– Additionally, bridges do not forward bad or
misaligned packets
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Network Devices: (continue…)
 Routers
• Filter out network traffic by specific protocol rather than by
packet address
• Routers also divide networks logically instead of
physically
• IP router can divide a network into various subnets so that
only traffic destined for particular IP addresses can pass
between segments.
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Network Devices: (continue…)
 Network Adapters:
A network adapter is the hardware installed in
computers that enables them to communicate
on a network.
They are small and lightweight and can be
connected to standard connectors on the back of
notebook computers so that the computer and network
adapter can be easily transported from network to
network
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Network Devices: (continue…)
 Network Adapters: (continue…)
 The hardware used to make connections between network
adapters and different transmission media depends on the
type of medium used.
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Network Cabling
Cable can be recovered in plastic, rubber, be careful
to get the correct type of cable for the type of
network card used.
Primary cable types:
•
•
•
Coaxial
Twisted pair
Shielded.
Unshielded.
Fiber optic
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Network Cabling: ( continue…)
•
Coaxial cable:
• Physical description:
Coaxial cable consists of two conductors, it
consists of hallow outer cylindrical conductor that
surrounds single inner wire conductor.
• The outer conductor is covered with ajacet or shield.
• Coaxial cable has diameter of from 0.4 to 1 inch.
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Network Cabling: ( continue…)
Coaxial cable: ( continue…)
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Applications
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•
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Television distribution
Long-distance telephone transition
Short-run computer system links
Local area networks
Transition characteristics
•
•
Coaxial cable is used to transmit both analog
and digital signals.
For long-distance transition of analog signals,
amplifiers are needed every kilometers.
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Coaxial cable: ( continue…)
Out shield
Insulation (PVC,Teflon)
Copper wire mesh or
aluminum sleeve
Conducting core
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Network Cabling: ( continue…)
Twisted pair:
•
• The Most expansive and most widely used guided transition
medium is twisted pair.
• Cable showing various layers.
Physical description
A twisted pair consists
of two insulated copper
wires arranged in regular
spiral pattern. wire pair
acts as a single communication link.
have thicknesses of from 0.016 to 0.036 inches.
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Network Cabling: ( continue…)
Twisted pair: (continue…)
 Applications
• That used in the telephone network, for local area network
supporting personal computer.
• Twisted pair is much less expensive than the others and
is easier to work .
• It is more limited in terms of data rate and distance.
 Transition characteristics
• For analog signal, amplifiers are required about every 2 to
3 km, for digital signal ,repeater are required every 100 or
150 m.
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Network Cabling: ( continue…)
Unshielded and shielded twisted pair:
Unshielded twisted pair (utp) is ordinary telephone wire
Recognizes three categories of utp cabling:
•
•
•
Category 3.utp cables and associated connecting
hardware whose transition characteristics are specified
up to 16 MHZ.
Category 4.utp are specified up to 20MHZ.
Category 5.utp are specified up to 100 MHZ
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Network Cabling: ( continue…)
Optical fiber:
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Physical description
•
•
An optical fiber is a thin(2 to 125 mm).
Applications
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Greater capacity
Smaller size and higher weight.
Electromagnetic isolation
Greater repeater spacing.
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Network Cabling: ( continue…)
Optical fiber:
•
• Transition characteristics
Optical fiber system operate in the range of about 10^14 to
10^15 HZ.
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The End
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