its about network

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NETWORK
SHARONE SINGH
PGDM 2017-19
13051

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INTRODUCTION OF NETWORK
• In computer science this ability in computer networks is data. The
locations access to the ability in network is called a "Node". Collection of
devices so that the information can be exchanged efficiently.
• DEFINATION:- A group of interconnected (via cable and/or wireless)
computers and peripherals that is capable of sharing software and
hardware resources between many users. The Internet is a global network
of networks.

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NETWORK OF NETWORKS
• Internet is not one single being, it is a massive interconnection of hosts
such as your computer, and another halfway across the world. The answer
lies in the interconnection of many ISPs themselves. ISPs can be
categorized into Tier 1,2 and 3 ISPs. Tier 1 ISPs are major internet service
providers that usually sell access to smaller Tier 2 ISPs.

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SERVERS AND CLIENTS
o In networking there are always two computers in the connection. The
server and the client. The server listens and waits for clients to connect
to it and the client connects to the server. To use the above example the
server is the computer that holds the web site and the client is your web
browser. So when you type in http://www.google.com, your web browser
connects to the server at http://www.google.com and they start
communicating.
PROTOCOL
o A protocol is the language that computers use to talk to each other. If
two computers want to talk to each other they need to know the same
language. If they don't know the same language they can't talk to each
other. For example HTTP, FTP, TCP, PPP.

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TOPOLOGY
• A network topology is the arrangement of a network, including its nodes
and connecting lines. There are two ways of defining network geometry:
the physical topology and the logical (or signal) topology.
• The physical topology of a network is the actual geometric layout of
workstations.
• Common configurations include the bus topology, linear bus, mesh
topology ring topology star topology tree topology and hybrid topology.

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TYPES OF TOPOLOGY
• Ring topology
• Bus topology
• Star topology
• Mesh topology
• Tree topology
• Hybrid topology

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BUS TOPOLOGY
• Bus topology is a network type in which every computer and network
device is connected to single cable. When it has exactly two endpoints,
then it is called Linear Bus topology.

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• Features of Bus Topology
• It transmits data only in one direction.
• Every device is connected to a single cable
• Advantages of Bus Topology
• It is cost effective.
• Cable required is least compared to other network topology.
• Used in small networks.
• It is easy to understand.
• Easy to expand joining two cables together.
• Disadvantages of Bus Topology
• Cables fails then whole network fails.
• If network traffic is heavy or nodes are more the performance of the
network decreases.
• Cable has a limited length.
• It is slower than the ring topology.

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RING TOPOLOGY
• It is called ring topology because it forms a ring as each computer is
connected to another computer, with the last one connected to the first.
Exactly two neighbors for each device.

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Features of Ring Topology
• The transmission is unidirectional, but it can be made bidirectional by
having 2 connections between each Network Node, it is called Dual Ring
Topology.
• In Dual Ring Topology, two ring networks are formed, and data flow is in
opposite direction in them. Also, if one ring fails, the second ring can act
as a backup, to keep the network up.
• Data is transferred in a sequential manner that is bit by bit. Data
transmitted, has to pass through each node of the network, till the
destination node.
• Advantages of Ring Topology
• Transmitting network is not affected by high traffic or by adding more
nodes, as only the nodes having tokens can transmit data.
• Cheap to install and expand
• Disadvantages of Ring Topology
• Troubleshooting is difficult in ring topology.
• Adding or deleting the computers disturbs the network activity.
• Failure of one computer disturbs the whole network.

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STAR TOPOLOGY
• In this type of topology all the computers are connected to a single hub
through a cable. This hub is the central node and all others nodes are
connected to the central node.

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• Features of Star Topology
• Every node has its own dedicated connection to the hub.
• Hub acts as a repeater for data flow.
• Can be used with twisted pair, Optical Fibre or coaxial cable.
• Advantages of Star Topology
• Fast performance with few nodes and low network traffic.
• Hub can be upgraded easily.
• Easy to troubleshoot.
• Easy to setup and modify.
• Only that node is affected which has failed, rest of the nodes can work
smoothly.
• Disadvantages of Star Topology
•
Cost of installation is high.
• Expensive to use.
• If the hub fails then the whole network is stopped because all the nodes
depend on the hub.
• Performance is based on the hub that is it depends on its capacity

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MESH TOPOLOGY
• IT is a point-to-point connection to other nodes or devices. All the network
nodes are connected to each other. Mesh has n(n-1)/2 physical channels
to link n devices.
• There are two techniques to transmit data over the Mesh topology, they
are :
o Routing
o Flooding
o ROUTING :-IN routing, the nodes have a routing logic, as per the network
requirements. Like routing logic to direct the data to reach the destination
using the shortest distance. Or, routing logic which has information about
the broken links, and it avoids those node etc. We can even have routing
logic, to re-configure the failed nodes

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• Flooding :-In flooding, the same data is transmitted to all the
network nodes, hence no routing logic is required. The
network is robust, and the its very unlikely to lose the data.
But it leads to unwanted load over the network.

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TREE TOPOLOGY
• It has a root node and all other nodes are connected to it forming a
hierarchy. It is also called hierarchical topology. It should at least have
three levels to the hierarchy.

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• Features of Tree Topology
• Ideal if workstations are located in groups.
• Used in Wide Area Network.
• Advantages of Tree Topology
• Extension of bus and star topologies.
• Expansion of nodes is possible and easy.
• Easily managed and maintained.
• Error detection is easily done.
• Disadvantages of Tree Topology
• Heavily cabled.
• Costly.
• If more nodes are added maintenance is difficult.
• Central hub fails, network fails.

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HYBRID TOPOLOGY
o It is two different types of topologies which is a
mixture of two or more topologies. For example if in
an office in one department ring topology is used
and in another star topology is used, connecting
these topologies will result in Hybrid Topology (ring
topology and star topology).

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• Features of Hybrid Topology
• It is a combination of two or topologies
• Inherits the advantages and disadvantages of the topologies included
• Advantages of Hybrid Topology
• Reliable as Error detecting and trouble shooting is easy.
• Effective.
• Scalable as size can be increased easily.
• Flexible.
• Disadvantages of Hybrid Topology
• Complex in design.
• Costly.

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NETWORK COMPONENTS
• Computer network components include the major
parts that are needed to install a network both at the
office and home level. Before delving into the
installation process, you should be familiar with each
part so that you could choose and buy the right
component that fits with your network system.
• These hardware components
include cable, Hub, Switch, NIC (network interface
card), modem and router.

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1. Network Interface Card
• Network adapter is a device that enables a computer to talk
with other computer/network. Using unique hardware
addresses (MAC address) encoded on the card chip, the data-
link protocol employs these addresses to discover other
systems on the network so that it can transfer data to the
right destination.
• There are two types of network cards: wired and wireless.

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2. Hub
• Hub is a device that splits a network connection into multiple computers.
It is like a distribution center. When a computer request information from
a network or a specific computer, it sends the request to the hub through
a cable. Currently Hubs are becoming obsolete and replaced by more
advanced communication devices such as Switches and Routers.
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• 3. Switch
• Switch is a telecommunication device grouped as one of computer
network components. Switch is like a Hub but built in with advanced
features. It uses physical device addresses in each incoming messages so
that it can deliver the message to the right destination or port.
• Like Hub, switch don’t broadcast the received message to entire network,
rather before sending it checks to which system or port should the
message be sent.

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• 4. Cables and connectors
• Cable is one way of transmission media which can transmit
communication signals. The wired network typology uses special type of
cable to connect computers on a network.
• There are a number of solid transmission Media types, which are listed
below. - Twisted pair wire
• It is classified as Category 1, 2, 3, 4, 5, 5E, 6 and 7. Category 5E, 6 and 7 are
high-speed cables that can transmit 1Gbps or more. -
• Coaxial cable
• Coaxial cable more resembles like TV installation cable. It is more
expensive than twisted-pair cable but provide high data transmission
speed.
• Fiber-optic cable
• It is a high-speed cable which transmits data using light beams through a
glass bound fibers.

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• 5. Router
• When we talk about computer network components, the other device
that used to connect a LAN with an internet connection is called Router.
When you have two distinct networks (LANs) or want to share a single
internet connection to multiple computers, we use a Router.
• In most cases, recent routers also include a switch which in other words
can be used as a switch. You don’t need to buy both switch and router,
particularly if you are installing small business and home networks.
• There are two types of Router: wired and wireless

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• 6. Modems
• A modem enables you to connect your computer to the available internet
connection over the existing telephone line. Like NIC, Modem is not
integrated with a computer motherboard. It comes as separate part
which can be installed on the PCI slots found on motherboard.
• A modem is not necessary for LAN, but required for internet connection
such as dial-up and DSL.
• There are some types of modems, which differs in speed and transmission
rate. Standard PC modem or Dial-up modems (56Kb data transmission
speed), Cellular modem (used in a laptop that enables to connect while on
the go), cable modem (500 times faster than standard modem) and DSL
Modems are the most popular.

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DATA COMMUNICATIONS
o Data communications (DC) is the process of using computing and
communication technologies to transfer data from one place to another,
and vice versa. It enables the movement of electronic or digital data
between two or more nodes, regardless of geographical location,
technological medium or data contents.

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TYPES OF DATA
COMMUNICATIONS
• Simplex
• A simplex communication system sends a message in only one direction.
The message source works as the transmitter. It sends the message over
the data channel to the receiver. The receiver is the destination of the
message. Examples of simplex data communication include radio stations
and TV broadcasts.

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• Half Duplex
• A half-duplex data communication system provides messages in both
directions but only allows transfer in one direction at a time. Once a party
begins sending a transmission, the receiver must wait until the signal stops
before responding. If the two data transfers attempt to send at the same
time, they both fail. For instance, if you talk on a CB radio, you press a
button and speak.

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• Full Duplex
• A full duplex is a communication that works both ways at the same time.
Essentially, full duplex data communication is a set of two simplex
channels, one works as a forward channel and the other as a reserve
channel. The two channels link together at some point. An example of a
full duplex communication system is a landline telephone.

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• Serial
• Serial communication takes a data communication, breaks it up into small
pieces, and sends the message one bit at a time through a channel. The
receiver collects the small bits and reassembles them to compose the
original message. Serial communication is the most common type of
communication between electronic devices. One example of serial
communication in action is the data sent from a modem to the service
provider.

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