networking essentials i rev

7/29/2019 Networking Essentials i Rev

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COMPUTER NETWORKING

(Part-I)


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Definition of a Computer Network

Definition

Interconnection of two or more

Computers in varieties of ways form aComputer Network.

A apart from Computers in a

Network, others elements are also available.


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Objective of a Computer Network

A Computer Network allows:-

-Sharing of Resources

-Security & Preservation of Data

-Transfer of Data

-Restricting the Accesses.


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Basic Network Components

Broadly, there are two types of Components of a

Computer Network-

-Hardware Components

-Software Components

The H/W Components are the physical elements.

These are visible devices of a Network.

The S/W Components are abstract items which

can only be felt and their presence can be realized.


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H/W Network Components

H/W Network Components are usually-

-Servers

-User Terminals or PCs

-Printers/Scanners

-Hubs/Switches/Routers/Gateways

-Modems

-Cables & Connectors

-Network Interface Cards


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S/W Network Components

Network Operating Systems (NOS) are meant formanaging resources of a Network efficiently UNIX,RTOS are some of the examples of NOS.

Application S/Ws are user based applications likeTelephone Billing System, Railway PassengerReservation System etc. Applications S/Ws arewritten in certain High Level Computer Languages.

C, CHILL etc are examples of Computer Languages.


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Outlines of H/W Components

Server- It is the most powerful component of aNetwork for controlling the Network activities. ANetwork may have one or more Servers.

User Terminals or PCs- Normally these areComputer Terminals or PCs from where users areuse the resources of the Network.

Printers-As the name indicates, the Printers aremeant for taking hard copies or printouts.

Scanners- These are devices used to scandocuments, Pictures , Photos etc.


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(Contd.) Hubs are simple devices used for

interconnecting the various Network

components Like Terminals, Servers etc. SwitchesThey are also somewhat simple

but more smarter than Hubs and offerdedicated bandwidths. Switches are DataLink Layer device.


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(Contd.) Routers- They are more smarter than Hubs and

Switches. Based on routing tables, the Routerscan ensure travel of packets through efficient

paths. Routers operate in Network Layers. GatewaysA Gateway is a super-intelligent

Router It has own Processor and Memory toperform complex functions.


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(Contd.)

Cables and Connectors

-Commonly used Cables are- STP,UTP,CXL and OFC.

-STP ( Shielded Twisted Pair) Cables- These areTwisted Pair Cables with a copper braid of foil thatoffers resistance to noise.

- UTP ( Unshielded Twisted Pair ) Cables- Such Cablesdonot contain any shield and suitable for easyinstallation. There are various Categories- 1 to 6.


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Outlines of H/W

Components ( Contd.)-CXL ( Co-axial ) Cables- Coaxial Cables arecarriers of signal of higher frequency ranges. Theyalso find usages in Local Computer Networks.

-OF (Optical Fibre ) Cables-These are suitable forBack-Bone devices in larger Networks. Highlyreliable. Typical speeds are in the ranges of 100mbps and may go up-to the order of gbps.


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( Contd.)

Commonly used connectors are-

-RJ45 Connectors suitable specially for UTPCable terminations.

-T-Connectors, Banana Connectors andTerminators are used for Coaxial Cable media

connectivity.


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(Contd.) Modems-

-Modem stands for Modulator/Demodulator.

- A Modem converts digital signals into Analog Signals.

-Analog signals may be converted back into Digital by

the Modem.

- A modem may be put in Dial-up or Leased Lineconnected mode.

-Modems of Wide ranges of speeds are available.


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(Contd.) Network Interface Cards (NICs)-

-This is the Interface between the User PC

and the Network.-Also Known as Network Adapters.

-Speeds available are 10/100 mbps generally.

-An NIC variety may be of 8/16/32 bits etc..


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Outlines of S/W Components

Network Operating Systems (NOS)-

-UNIX is one of the the most popular and

Universal Multi-User O.S.-Widely being used World Wide.

-Various Flavours are also available.

-UNIX got its real shape from AT&Ts Bell

Laboratories and Berkeley University of USA.


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Outlines of S/W Components

(Contd.)-RTOS is a Multi-User O S suitable forTelecom Applications.

-Guidelines are provided by ITU. Application S/WsUser specific S/Ws

developed by various vendors based on

customer requirements.

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