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Local Area Network
IntroductionIn general terms LAN refers to group of computers
interconnected into a network so that they are able
to communicate,exchange informaion and share
resources.for eg.printer,file server.In other words the
same computer
resources can be used by multiple users in the
network.Each computer in LAN can effectively send and
receive any
information.This information is in form of data packets.
The LAN is high speed network
that covers relatively small geographic area.such as
single room,college campus etc.Every p.c.has a
circuit board known as network interface card for
interconnecting computer to each other.The server
of a
LAN system should have large capacity hard disk
known as network server.
Components of LAN1]Network devices- such as
workstation,printers,file server
which are normally accessed by all other
computers.
2]Network communication devices-such as
hubs,routers,
switches used for network opreation.
3]Network interface card-for each netwwork device
required to access the network.
4]Cable is physical tmansmission media.
5]Netwok opreating system-software application
required
to control the use of the network LAN standards.
Network communication devices
• 1]Router-A device that amplifies and
regenerates signals,so that they can travel for
longer distance on the cable.
• 2]Router-The basic function of the router is to
route the traffic from one network to another
network efficientlyIt provides intelligent
redundancy and security required to select the
optimum path.Usually routers are used for
connecting remote networks.
• 3]Hub-A typical hub is a multi-port repeater.The
signals received at the backbone is regenerated
and transmitted
• to all other ports.
Internet access over LAN
There are various methods of connecting a LAN to the
internet gateway,which are as follows.
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1]Dial-up
2]Leased Line
3]ISDN
4]VSAT Technology
5]RF Technology
6]Cable Modem
Switch
A network switch is a small hardware device that
multiple computer together within one local area
network.This a device with multiple port which
forwards packets from one port to another.In case
of 10mbps ethernet switch,each port supports
dedicated 10mbps bandwidth.Ethernet switch is
fast emerging as a replacement of the traditional
thick backbone and best way to improve
perfornmance of the network.switch configure
themselves automatically.They listen to traffic on
each ethernet port and discover to which port each
attached device is connected.
Wide area network
A wide area network spans or covers large
geographic
Area often a country.It contains a no.of machines
which
Are running user application and programs.We can
call these
Host.The host are connected to the subnet.The
subnet are
Owned by the customer pc’s,where a subnet is
typically owned and operated by telephone computer
or internet serveice
Provider.The job of the host is to carry message from
host to host just as a telephone system which carries
words from speaker to listener.
Metropolitan area network
A metropolitan are network
Covers city.The best known eg.of MAN is the cable
television network available in many cities.This
system grows up or used in area where the poor air
television reception.In MAN a larege antina was
palced on the top of near by hill and signal was biked
to the customer house
There are no.of companies Begans jumping into this
business
and getting contract from the city govt. to wire up the
entire city.
The next step was tv Programming and even entire
channels
were specialised Such as all news,all sports,all
movies and so on.
Network topology
Network topology is the way to connect computer
or
Devices to the network.
1]BUS tolpology-In this topology all computers
share same bus ie.single communication
channel.Every computer can Communicate with
each
Other directly.This is the most commonly used
network topology.In this topology if fault occurs it
is very difficult to fint the fault.
2]RING topology- This topology connects the local
pc together in a ring shape using a single
communication channel in a close loop.In this
network data travels around the ring to each pc till
it arrives at the required destination.
3]STAR topology-This topology connects all
computers to a central hub.Here the computer
connect directly to a central hub for communicate
with each other then they can send singnal
through a central hub.
4]MESH topology-This is the variation of ginr
network or topology.There all computer are
connented directly so that they can be direct
communication between the computer.
Transmission Prototcol
• 1]FTP-It is the file transfer protocol used to transfer files
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Between computers.This works on client server
technology.
2] Telnet-It is used for connect one computer to another
Computer.This also works on client server technology.
3] 3]SMTP-Simple mail transfer protocol ie used for send
the electronic mail.
4]DHCP-The dynamic host configuration protocol is used
to assign the IP address to the network cards.
5]TCP-Transport control protocol is a connection
oriented reliable Protocol working at transport layer.
6] IP-Internet protocol is used for software addesssing of
computer and works at data link layer.
• 7]UDP-User datagram protocol is aconnection less
unreliable protocol working at the transport layer.
• 8]ICMP-Internet control message protocol is used to
perform network error reporting and status.It works at the
transport layer.
• 9]IGMP-Internet group management protocol is used to
manage multicast groups and works at the transport
layer.
• 10]APR-Address resolution protocol is used to resolvee
the hardware address of the card to package the
ethernet data.It works at data link layer.
• 11]RARP-Reserver address protocol used for disk less
computers to determine their IP address using the
network.It works at data link layer.