NETWORK
TOPIC
NETWORK
Is a group of anything with two or
more than two objects linked together for sharing information or services with
each other!
NETWORKING
Is the process of establishing that
network in order to share data, files, internet and printer E.T.C
SERVER
A computer on a network that manages
network resources, meaning they do not perform any other tasks besides their
server tasks.
CLIENT
A computer that can request information
or processing from a server. Client and servers can be connected to each other
on a LAN or MAN and MAN
IP address
{Internet Protocol Address}
Also known as
“internet address” a unique number for a computer or devices such as a printer
connected to the Internet identifying its location. Usually written as 4 numbers or
sequences of numbers separated by periods for example 192.168.10.1
NIC {Network Interface Card}
A board inserted inside a computer or peripheral device so that can
be connected to a network also called a Network
Interface Card/Board {N.I.B}
MAIN TYPES OF NETWORK
1)
Local Area Network {LAN}
2)
Metropolitan Area Network {MAN}
3)
Wide Area Network {WAN}
4)
Very Wide Area Network {VWAN}
1.
LOCAL
AREA NETWORK {LAN}
Consist of a computer network at a single site typically and individual
office building or one campus.
LAN
is a very useful for sharing resources, such as data storage and printers
LAN
can be built with relatively inexpensive hardware hubs, switches, network
adapter and Ethernet cables.
By
expanding the definition of a LAN to the services that it provides, two different
operating modes can be defined:
1. PEER-TO-PEER
In a "peer-to-peer"
network, in which communication is carried out from one computer to another,
without a central computer, and where each computer has the same role.
2. BASED ON SERVER
In a "client/server"
environment, in which a central computer provides network services to users.
2.
METROPOLITAN
AREA NETWORK {MAN}
Consist
of a computer network across an entire city small region or geographical area
MAN is
larger than a LAN which typical limited to a single building or site depending
on configuration, this type of Network can cover an area from several Miles to
tens of Milles.
MAN is
often used to connect several VLAN’s together to form a bigger Network
3.
WIDE AREA NETWORK
A
wide area network or WAN occupies a very large area such as an entire country,
entire region or the entire world.
WAN can contains multiple smaller networks
such as LANs or MAN the Internet is the best known example of a public WAN
NETWORK TOPOLOGY
What is a TOPOLOGY?
• Network topologies
describe the ways in which the elements of a network are mapped. They describe
the physical and logical arrangement of the network nodes.
• The physical
topology of a network refers to the configuration of cables, computers, and
other peripherals
DIFFERENT TYPES OF TOPOLOGIES
• Bus Topology
• Star Topology
• Ring Topology
• Mesh Topology
• Tree Topology
• Hybrid Topology
1. BUS TOPOLOGY
• All the nodes (file server,
workstations, and peripherals) on a bus topology are connected by one single
cable.
• A bus topology consists of a main run of cable with a terminator at
each end. All nodes (file server, workstations, and peripherals) are connected
to the linear cable.
• Popular on LANs because they are inexpensive and easy to install.
Bus Topology Advantages of Bus
Topology
• It is Cheap, easy to handle
and implement.
• Require less cable
• It is best suited for small
networks.
Disadvantages of Bus Topology
• The cable length is limited.
This limits the number of stations that can be connected.
• This network topology can perform well only for a limited number of
nodes
2. RING TOPOLOGY
• In a ring network, every device has exactly two neighbors for
communication purposes.
• All messages travel through a ring in the same direction. .
• A failure in any cable or device breaks the loop and can take down
the entire network.
• To implement a ring network we use the Token Ring technology
• A token, or small data packet, is continuously passed around the
network. When a device needs to transmit, it reserves the token for the next
trip around, and then attaches its data packet to it.
Advantage of Ring Topology
• Very orderly network where every device has access to the token and
the opportunity to transmit.
• Easier to Manage than a Bus Network
• Good Communication over long distances
• Handles high volume of traffic
Disadvantages of Ring Topology
• The failure of a single node of the network can cause the entire
network to fail.
• The movement or changes made to network nodes affects the performance
of the entire network
3. STAR TOPOLOGY
·
In a star network, each node (file server,
workstations, and peripherals) is connected to a central device called a hub.
·
The hub takes a signal that comes from any node
and passes it along to all the other nodes in the network.
·
Data on a star network passes through the hub,
switch, or concentrator before continuing to its destination.
·
The hub, switch, or concentrator manages and
controls all functions of the network.
·
The star topology reduces the chance of network
failure by connecting all of the systems to a central node.
Advantages of Star Topology
• Easy to manage
• Easy to locate problems (cable/workstations)
• Easier to expand than a bus or ring topology.
• Easy to install and wire.
• Easy to detect faults and to remove parts.
Disadvantages of Star Topology
• Requires more cable length than a linear topology.
• If the hub or concentrator fails, nodes attached are disabled.
• More expensive because of the cost of the concentrators.
4. TREE TOPOLOGY
·
A tree topology (hierarchical topology) can be
viewed as a collection of star networks arranged in a hierarchy.
·
This tree has individual peripheral nodes which
are required to transmit to and receive from one other only and are not
required to act as repeaters or regenerators.
·
The tree topology arranges links and nodes into
distinct hierarchies in order to allow greater control and easier
troubleshooting.
·
This is particularly helpful for colleges,
universities and schools so that each of the connect to the big network in some
way.
Advantages of a Tree Topology
• Point-to-point wiring for individual segments.
• Supported by several hardware and software vendors.
• All the computers have access to the larger and their immediate
Networks.
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 topology
5. MESH TOPOLOGY
•
In this topology, each node is connected to
every other node in the network.
•
Implementing the mesh topology is expensive and
difficult.
•
In this type of network, each node may send
message to destination through multiple paths.
•
While the data is travelling on the Mesh Network
it is automatically configured to reach the destination by taking the shortest
route which means the least number of hops.
Advantage of Mesh Topology
• No traffic problem as there are dedicated links.
• It has multiple links, so if one route is blocked then other routes
can
be used for data communication.
• Points to point links make fault identification easy.
Disadvantage of Mesh Topology
• There is mesh of wiring which can be difficult to manage.
• Installation is complex as each node is connected to every node.
• Cabling cost is high
6. HYBRID TOPOLOGY
• A combination of any two or more network topologies.
• A hybrid topology always accrues when two different basic network
topologies are connected.
• It is a mixture of above mentioned topologies. Usually, a central
computer is attached with sub-controllers which in turn participate in a
variety of topologies
Advantages of a Hybrid Topology
• It is extremely flexible.
• It is very reliable.
Disadvantages of a Hybrid
Topology
• Expensive
GUIDED MEDIA
(WIRED)
Guided media includes everything
that ‘guides’ the transmission. That usually takes the form of some sort of a
wire. Usually copper, but can also be optical fiber.
TYPES OF PHYSICAL WIRE
I.
TWISTED PAIR
CABLE
II.
COAXIAL CABLE
III.
FIBER OPTIC
CABLE
1. TWISTED PAIR CABLE
Twisted pair cable
consists of a pair of insulated wires twisted together. It is a cable type used
in telecommunication for very long time. Cable twisting helps to reduce noise
pickup from outside sources and crosstalk on multi-pair cables.
There are two types of twisted-pair cable
(i) SHIELDED TWISTED PAIR CABLE (STP)
(ii) UNSHIELDED TWISTED PAIR CABLE
(UTP)
(i) SHIELDED
TWISTED PAIR CABLE
Shielded Twisted-Pair cable and STP cable was first
developed by IBM for Token Ring networks. It consists of two individual wires
wrapped in a foil shielding that helps provide more reliable data transmission.
Shielded
twisted pair cable is available in three different configurations:
a) Each
pair of wires is individually shielded with foil.
b) There
is a foil or braid shield inside the jacket covering all wires (as a group).
c) There
is a shield around each individual pair, as well as around the entire group of
wires (referred to as double shield twisted pair).
(ii) UNSHIELDED
TWISTED PAIR
Unshielded Twisted Pair, a UTP cable
is a cable used in computer networking that consists of two shielded wires
twisted around each other. The image shows various network cables, including
UTP.
2. COAXIAL
CABLE
Commonly known as coax
carries a signal at much higher frequencies than twisted pair. Instead of
having two wires, there is a primary ‘core’ wire in the center, with an
insulator, and an outer conductor that serves as a shield and insulator. Cable
TV uses Coaxial Cable.
There are a few standards:
1. RG-8: Used in Thick
Ethernet.
2.
RG-9: Used in Thick Ethernet.
3. RG-11: Used in Thick
Ethernet.
4. RG-58: Used for Thin
Ethernet.
5. RG-59: Used for TV.
3. FIBER OPTIC CABLE
Fiber Optics Transmission
I.
Low
Attenuation
II.
Very
High Bandwidth (THz)
III.
Small
Size and Low Weight
IV.
No
Electromagnetic Interference
V.
Low
Security Risk
VI.
Elements
of Optical Transmission
VII.
Electrical-to-optical
Transducers
VIII.
Optical
Media
IX.
Optical-to-electrical
Transducers
X.
Digital
Signal Processing, repeaters and clock recovery
Types
of Optical Fiber
1.Multi-Mode:
(a) Step-index – Core and Cladding
material has uniform but
different refractive index.
(b) Graded Index – Core material has
variable index as a function
of the radial distance from the center.
2.
Single Mode
– The core diameter is almost equal to
the
EE4367 Telecom. Switching &
Transmission Prof. Murat Torlak
Single Mode
– The core diameter is almost equal to
the
wave length of the emitted light so that
it propagates along
a single path.
UNGUIDED MEDIA
Transmission
media then looking at analysis of using them UNGUIDED transmission media is
data signals that flow through the air. They are not guided or bound to a
channel to follow.
Following are
unguided media used for data communication
a. Radio
Transmission
b. Microwave
c.
Satellite
communication
1. RADIO
TRANSMISSION
Is
the radiation {wireless transmission} of electromagnetic energy through space.
The biggest use of radio waves as their AMPLITUDE, FREQUENCY, PHASE or PULSE
WIDTH.
THERE ARE THREE
TYPES OF RF {Radio Frequency}
i.
Ground wave
ii.
Sky wave
iii.
Line of sight
2. SATELLITE
Are transponders {units that
receive on one frequency and retransmit on another} that are set in
GEOSTATIONARY ORBITS directly over the equator. These Geostationary orbits are
36,000km from the Earth’s surface. At this point the gravitationalpull of the
Earth and centrifugal force of Earth’s rotation are balanced and cancel each
other out.
CETRIFUGAL FORCE is the rotational foooorce placed on the satellite
that wants to fling it out into space.
UPLINKS and DOWNLINKS are also called EARTH
STATIONS because they are located on the Earth. The footprint is the “SHADOW” that the satellite can transmit to, the
shadow being the area that can receive the satellite’s transmitted signal.
MICROWAVES
Electromagnetic waves having frequencies
between 1 and 300GH called microwaves, Microwaves are unidirectional. When an
antenna transmits microwaves they can be narrowly focused. This means that the
sending and receiving antenna need to be aligned. The unidirectional property
has an obvious advantage. A pair of antennas can be aligned without interfering
with another pair of aligned antennas.
The following describes some
characteristics of microwave propagation
1. Microwave
propagation is a LINE-OF-SIGHT. Since the towers with the mounted antennas need
to be in direct sight of each other, towers that are far apart need to be very
tall. The curvature of the earth as well as other blocking obstacles do not
allow two short towers to communicate by using microwaves, repeaters are often
need for long distance communication.
2. Very high-frequency microwaves cannot
penetrate walls this characteristics can be a disadvantage if receives are
inside buildings.
3. The microwave
band is relatively wide, almost 299GHz therefore wider sub bands can be
assigned and a high data rate is possible.
4. Use of certain portions of the band requires
permissions from authorities.
TYPES OF
ANTENNA
I.
Horn
Antenna
II.
Parabolic
Antenna
III.
Slot
Antenna
IV.
Dipole
Antenna
V.
Dielectric
Antenna
VI.
Printed
Antenna
VII.
Phase Array
Antenna
HORN ANTENNA
·
horn antenna is used in many applications at
microwaves where reasonable levels of directivity are needed. There are several
types including the pyramid horn antenna, conical horn and the corrugated horn
antenna.
·
Horn antenna is used in the transmission and reception
of RF microwave signals, and the antenna is normally used in conjunction with
waveguide feeds.
·
A horn antenna form of antenna that consists of a
flared waveguide which is shaped like a horn and it has the effect that it
enables a transition between the waveguide and free space and it also directs
radio waves in a beam.
PARABOLIC
ANTENNA
A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of APARABOLA, to direct the radio waves. The most common form is shaped like
a dish and is popularly called a dish antenna or parabolic
dish.
SLOT
ANTENNA
A slot antenna consists
of a metal surface,
usually a flat plate, with a hole or slot cut out. When the plate is driven as
an antenna by a
driving frequency, the slot radiates electromagnetic waves in a
way similar to a dipole
antenna. The shape and size of the slot, as well as the driving
frequency, determine the radiation
distribution pattern. Often the radio waves are provided by a waveguide, and the
antenna consists of slots in the waveguide. Slot antennas are often used
at UHF and microwave frequencies
instead of line antennas when greater control of the radiation
pattern is required. Slot antennas are widely used in radar antennas,
for the sector antennas used for cell phone
base stations, and are often found in standard desktop microwave sources
used for research purposes.
DIPOLE
ANTENNA
In radio and telecommunications a dipole antenna or doublet[1] is
the simplest and most widely used class of antenna.[2][3]It consists
of two identical conductive elements[4] such
as metal wires or rods, which are usually bilaterally symmetrical.[3][5][6]The driving
current from the transmitter is applied, or for receiving
antennas the output signal to the receiver is taken,
between the two halves of the antenna. Each side of the feedline to
the transmitter or receiver is connected to one of the conductors. This
contrasts with a monopole
antenna, which consists of a single rod or conductor with one side
of thefeedline connected
to it, and the other side connected to some type of ground.[6] A
common example of a dipole is the "rabbit ears" television antenna found on broadcast
television sets
DIELECTRIC
ANTENNA
A dielectric
resonator antenna (DRA) is a radio antenna mostly
used at microwave frequencies and higher, that consists of a block
of ceramic material
of various shapes, the dielectric resonator, mounted on a metal
surface, a ground plane. Radio waves are introduced into
the inside of the resonator material from thetransmitter circuit
and bounce back and forth between the resonator walls, forming standing
waves. The walls of the resonator are partially transparent to
radio waves, allowing the radio power to radiate into space
PRINTED
ANTENNA
A patch antenna is a narrowband, wide-beam antenna
fabricated by etching the antenna element pattern in metal trace bonded to an
insulating dielectric substrate, such as a printed circuit board, with a
continuous metal layer bonded to the opposite side of the substrate which forms
a ground plane. Common MICRO STRIP antenna shapes
are square, rectangular, circular and elliptical, but any continuous shape is
possible. Some patch antennas do not use a dielectric substrate and instead are
made of a metal patch mounted above a ground plane using dielectric spacers
PHASE ARRAY
ANTENNA
A phased array
antenna is composed of lots of radiating elements each with a phase shifter. Beams are
formed by shifting the phase of the signal emitted from each radiating element,
to provide constructive/destructiveinterference so as
to steer the beams in the desired direction.
|
BAND
|
RANGE
|
PROPAGATION
|
APPLICATION
|
|
VLF {Very Low frequency}
|
3-30KHz
|
|
|
|
LF {Low Frequency}
|
30-300KHz
|
|
|
|
MF {Middle Frequency}
|
300KH-3MHz
|
|
|
|
HF {High Frequency}
|
3-30MHz
|
|
|
|
VHF {Very High Frequency}
|
30-300MHz
|
|
|
|
UHF {Ultrahigh frequency}
|
300MHz-3GHz
|
|
|
|
SHF {Super high Frequency}
|
3-30GHz
|
|
|
|
EHF {Extremely High frequency}
|
30-300GHz
|
|
|
|
|
|
|
|
No comments:
Post a Comment