BY

YASHWANT IMBA/40534/11

PRASOON KUMAR IMBA/40535/11

AMIT KESARWANI IMBA/40547/11

AKASH MISHRA IMBA/40550/11

SHUBHAM IMBA/40551/11

ASHISH KR. SINHA IMBA/40555/11

NETWORKING

DATA COMMUNICATION: CONCEPTS

COMPONENTS

DATA MEASUREMENT

TRANSMISSION MODE

TRANSMISSION MEDIA

TRANSMISSION METHODS

MODULATION TECHNIQUES

COMPUTER NETWORK

TYPES: LANs & WANs

TOPOLOGIES

PROTOCOL & THE OSI MODEL

NETWORK DEVICES

INTRANET & EXTRANET

DATA COM

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NICATIO

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NCEPTS

Data communication is the exchange of data between 2 devices via some form of wired or wireless transmission medium.

It includes the transfer of data, methods of transfer, and the preservation of data during the transfer process.

The hardware and software, that facilitate data communication, taken together forms a communication system.

To initiate data communication, the communicating devices should be a part of an existing communication system.

For effective data communication, the following 3 fundamental characteristics should be considered:-

1) Delivery2) Accuracy3) Timeliness

What is Data Communication?

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Step-7

DATA COMMUNICATION: CONCEPTS

Data communication components:-

5 basic components in data communication system are:

1. Message2. Sender3. Receiver4. Medium5. Protocol

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Step-7

PROTOCPL

PROTOCPL

MESSAGE

SENDERTRANSMISSION

MEDIUM RECEIVER

The rate of data transmission is measured in Bandwidth.

Bandwidth refers to the maximum volume of information that can be transferred over any communication medium.

The more the information needed to transmit in a given period, the more the bandwidth required.

On digital circuits, bandwidth is measured in bits per second (bps). 1,000 bps = 1 Kbps.

Measurement of Data :- DATA COMMUNICATION CONCEPTS

The level of Bandwidths falls into 3 categories:1) Narrow Band

There is a single transmission channel of 64Kbps or less. There can be a number of 64Kbps transmission (N*64Kbps)

but not more than 1.544Mbps (also called T1 line).

2) Wide Band Bandwidth capacity lies between 1.544Mbps – 45Mbps.

3) Broad Band The bandwidth capacity is equal to 45Mbps or a T3 line.

DATA COMMUNICATION CONCEPTS

Measurement of Data :-

DATAData Transmission Mode :-

Data transmission mode refers to the direction of signal flow between 2 linked devices. There are 3 types of transmission modes:

Simplex

Half - Duplex

Full – Duplex

COM

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CONCEPTS

SIMPLEX

Simplex transmission is unidirectional, i.e., the information flows in one direction across the circuit, with no capability to support response in the other direction. Only one of the communicating devices transmits information, the other can only receive it. E.g.- TV communication.

DIRECTION OF DATA

ONE WAY COMMUNICATION

HALF- DUPLEX

In Half-Duplex mode, each communicating device can receive and transmit information, but not at the same time.When one device is sending, the other can only receive at that point of time. E.g. – wireless handsets (generally used by military personnel).

DIRECTION OF DATA AT T1

TWO WAY COMMUNICATION

DIRECTION OF DATA AT T2

(Signal goes in onedirection at a time)

FULL- DUPLEX

It is also known as simply the Duplex mode. It allows both communicating devices to transmit and receive data simultaneously.E.g. – Telephone network.

TWO WAY COMMUNICATION

(Signal goes in bothdirections simultaneously)

DIRECTION OF DATA AT ALL TIME

DATA COMMUNICATION: CONCEPTS

Transmission Media refers to the physical media through which signals are transmitted. It can be wired or wireless.The signal transmitted from one device to another is through Electromagnetic waves.An electromagnetic signal is the combination of electric and magnetic fields, vibrating in conjugation with each other.EM signals include power, voice, radio waves, infrared light, visible light, UV light, X-rays, Gamma-rays. All these together constitute an EM spectrum.These signals can travel through vacuum, air or any other transmission medium.

MediaGuided Media

Open Wire

Twisted PairUTP Cable

STP Cable

Coaxial Wire

Optical Fiber

Unguided MediaE.g.-Radio Frequency Propagation

Ground Wave

Ionospheric Propagation

Line of SightE.g.-FM Radio

E.g.-Microwave

E.g.-Satellite

Data Transmission Media

Type 1- Open WireOpen wire is used to transmit power through wires strung along power poles.Not recommended for long data transmission. The reasons are:-

1. Loss of energy problem.

2. It can easily be tapped.3. No shielding from

noise interference.

Coaxial cables have a single central conductor, which is made up of solid wire (usually Cu).Features:-

1. It is very robust and is used in Cable TV network.

2. It offers a bandwidth of 10Mbps.

Guided Media (Bound Media) – Wired Media

Type 2- Coaxial Wire

Guided Transmission Media use a cabling system that guide the data signals along a specified path through the cables. Hence they are also called bound media. 4 basic

types are- Open Wire, Coaxial Wire, Twisted Pair, and Optical Fiber.

Type 3- Twisted Pair Pairs of wires are twisted together which are surrounded by an insulating material and an outer layer called jacket. They are twisted to reduce noise. Each pair consist of wire, for receiving data signal, and a wire for transmitting data signal. Like open wire, these also transmit data in the form of current. Twisted pairs are used in a short distance communication (less than 100m) and they are available in 2 forms:- unshielded twisted pair (UTP) & shielded twisted pair (STP) cables.

UTP:-It is the most common

type of telecommunication medium in use today.

It is most suited for both data & voice transmission and hence commonly used in telephone systems.

They have a transmission speed of up to 9600bps.

STP:-STP cable has a metal foil

that covers each pair of insulated conductors.

The metal foil prevents infiltration of EM noise.The shield also helps to eliminate crosstalk.

Type 4- Optical Fiber

Optical fiber consists of thin glass fibers that can carry information in the form of visible light, unlike coaxial wire & twisted pair which carry signal as electrical current. The main components of an optical fiber are:

Core- it is a very narrow stand of glass.Cladding- it is a concentric layer of glass around the

core.Jacket- it is a protective coating of plastic which covers the cladding.

Optical fiber works on the principle that the core refracts the light and the cladding reflects the light; the core refracts the light and guides the light along its path. Whereas the cladding reflects any light back into the core and stops it from escaping through the medium. This principle is called TOTAL INTERNAL REFLECTION. The light pulses, which can be carried over long distances via optical fiber cable, carry information.

Type 4- Optical Fiber

Advantages of optical fiber:-

1. Since transmission is light-based rather than electricity, it is immune to noise interference.

2. Transmission distance is greater than other guided media because of les signal attenuation (degradation of quality over distance).

3. It is more secure because cable can not be tapped.

4. They are smaller and lighter than Copper wire and are free from corrosion as well.

5. Fiber optic offers, by far, the greatest bandwidth of any transmission system

Disadvantages of optical fiber:-

1. Fiber optic is expensive as it is costly to produce, maintain, and install.

2. They are more fragile as fiber optic tends to break easily as compared to Copper wire.

Type 1- Open Wire

1. Ground wave propagation: It follows the curvature of the

earth They have carrier frequencies of

up to 2MHz E.g.- AM Radio

2. Ionospheric propagation: The signal waves bounces off the

earth’s ionosphere layer Frequency range is 30-85MHz

Unguided Media – Wireless Media

Type 2- Coaxial Wire

Unguided Transmission Media is data signals that flow through the air.They are not bound to a fixed channel to flow.One of the most common unguided media of transmission is- radio frequency propagation.Radio frequency propagation: In RF propagation, the signal is carried over carrier waves (waves which carry signals over them), which have frequencies in the range of radio frequency spectrum.

There are 3 types of RF propagation:1. Ground wave propagation2. Ionospheric propagation3. Line of sight propagation

3. Line of Sight Propagation- It transmits exactly in the line of sight . The receiving station must be in the view of transmitting

station. Typically the line of sight due to the earth’s curvature is

50km to the horizon E.g.- FM Radio, Microwave, & Satellite.

50km

Microwave:•Microwave transmission is line of sight transmission.•The transmit station must be in visible contact with the receiving station.•Since the line of sight due to earth’s curvature is only 50 km to the horizon, repeater stations must be placed so the data signal can travel farther than the distance limit.

Satellite:•Satellites are set in geostationary orbits which are placed 36,000 km above the earth’s surface, and rotates in synchronization to earth.•The communication is carried through uplinks and downlinks. The uplink transmits the data to the satellite and downlink receives the data from the satellite.•Uplinks and downlinks are also called earth’s stations because they are located on earth.•The area shadowed by the satellite in which the data can be transferred is called the footprint.

DATA COMMUNICATION: CONCEPTS

Data Transmission Methods :- Any information to be transmitted from one communicating device to

another, by any media (wired or wireless), is first transformed into electromagnetic signals. Information is transmitted by 2 methods: ANALOG & DIGITAL.

Analog signals:An analog signal is a continuous waveform that changes smoothly over time.Most fundamental form of an analog signal is- the Sine Wave.Sine waves have 3 main characteristics: amplitude, frequency, & wavelength.

Digital Signals: Digital data is the data stored in the form of 0 and 1. When a signal is at high point, its value is 1 and when it is low, its value is 0. For data to be processed by computer or any digital device, they are converted into digital (machine readable) formats.

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Amplitude

Digital Signal Wave

Modulation Techniques

Amplitude Modulation:

In this modulation, the frequency of the carrier remains the same, only the amplitude changes to follow variation in the signal.

Frequency Modulation:

In this modulation, the amplitude of the carrier remains the same. The frequency change to follow variation in the signal.

DATA COMMUNICATION: CONCEPTS

Before an information is transmitted in a wide communication system, the information or modulating signals are superimposed on a carrier signal, which propagates by means of an electromagnetic wave. This process is called modulation.The carrier waves carry the signals to travel over ling distances.Generally, there are 2 forms of modulation- amplitude & frequency.

COMPUTER NETWORKWhat is a Computer Network ?

A computer network is simply two or more computers connected together to share information and resources.

The network connection can be through some wired media such as telephone lines, coaxial cables, or through wireless media such as satellite links, radio, an/or some other communication technique.

The purpose of connection is to share information an resources.

COMPUTER NETWORK

TYPES OF NETWORKS Broadly there are two types of network on the basis of various factors like the size of the network, the distance it covers, and the type of link used in the interconnection:

LAN- Local Area NetworkWAN- Wide Area Network

LAN:A LAN is a computer network that

spans only a small geographical area, such as an office, home or building.

Of the many computers connected, one computer is designated as the file server, which stores all the software that controls the network along with the software that can be shared by the computers attached to the network. Other computers connected to the file server are called workstations.

Most LANs use cable – connectivity.

Bandwidth- 10 to 100 Mbps. The cost of setting a LAN is low.

WAN: It is a connection of multiple LANs

which are geographically separate. They span over a large

geographical area such as cities, states, countries or even the whole world.

MANs use long-range communication technologies such as telephone lines, satellite links, etc.

Transmission speed is much higher as compared to LAN.

Cost of setting up a WAN is very high. There are several types of WAN:

Metropolitan area network(MAN) Public Access Network(PAN) Value Added Network(VAN) Virtual Private Network(VPN) INTERNET (largest WAN in existence)

Intranet – An intranet is a private LAN designed for use by everyone within an organization. An intranet might consist of an internal e-mail system, a message board and one or more Web site portals that contain company news, forms, and personnel information.

Access to an intranet’s web site is restricted by a firewall. Extranet – a network that connects people within your

company with people who are outside your company--all within a secure, password-protected network that can be accessed from anywhere.

COMPUTER NETWORK

INTRANET & EXTRANET

EXTRANET

INTRANET TYPES OF NETWORK

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EXAMPLE OF FIREWALL

Firewalls are systems that establish access control policies among networks.

They can block information from entering a network or from getting out of that network, they can permit different users to perform different kinds of operations, according to the user's authorizations.

                                                                                   

COMPUTER NETWORK

Information sharing: Authorized users can use other computers on the network to access and share information and data. This could include special group projects, databases, etc.

Hardware sharing: One device connected to a network, such as a printer or scanner, can be shared by many users.

Software sharing: Instead of purchasing and installing a software program on each computer, it can be installed on the server. All of the users can then access the program from a single location.

Collaborative environment: Users can work together on group projects by combining the power and capabilities of diverse equipment.

BENEFITS OF A NETWORK

RISKS OF NETWORK COMPUTINGThe security of a computer network is challenged everyday by:

• Equipment malfunctions• System failures

Note: equipment malfunctions and system failures may be caused by natural disasters such as floods, storms, or fires, and electrical disturbances

• Computer hackers• Virus attacks

Network Topologies

COMPUTER NETWORK

The term topology refers to the way a network is laid out, either physically or logically.

It can be considered as the network’s shape.

It is the geometric representation of the relationship of all the links.

There are 5 basic topologies-BusRingStarTreeMesh

Click icon to add picture•Connecting to a computer or peripheral to a linear bus is easy.

•It requires least amount of cabling, and hence is les expensive.

ADVANTAGE

DISADVANTAGE •Entire network shuts

down if there is a failure in the common bus or backbone (single cable).

•Heavy traffic can slow down a bus.

Bus Topology

All stations are connected to a single long cable. 

Any station can send a signal along the cable, which all other stations will receive.  Unlike ring topologies, the cable doesn't close a loop.

•It is easy to install and reconfigure.

•Every computer is given equal access to the ring. Hence, no single computer can monopolise the network.

ADVANTAGE

DISADVANTAGE •Failure in any cable or

node breaks the loop and can take down the entire network.

•Maximum ring length and number of nodes are limited.

RING Topology

In ring topology, computers are connected in a cable-loop.All messages travel through a ring in the same direction (clockwise or counterclockwise) until it reaches its destination.

•It is easy to install and wire.

•The network is not disrupted even if a node fails or is removed from the network.

•Fault detection and removal of faulty parts is easier.

ADVANTAGE

DISADVANTAGE •It requires a longer length of

cable.

•If the hub fails, nodes attached to it are disabled.

•The hub is costly, making the network expensive as compared to bus and ring topology.

STAR Topology

Computers and devices are connected via a centralised network component called HUB, which acts as a central controller.It uses mostly twisted pair cables. Other cables are also used.

Click icon to add picture

File Server

•The signal transmission distance increases as the signal passes through a chain of hubs.

•It allows for easy expansion of an existing network.

DISADVANTAGE •If the backbone line breaks, the

entire segment goes down.

•It is more difficult to configure and wire than other topologies.

tree TopologyIt is a combination of linear bus and star topologies.It consists of groups of star-configured workstations connected to a bus backbone cable .Not every node plugs directly to the central hub. The majority of nodes connect to a secondary hub that in turn is connected to the central hub. Each secondary hub in this topology functions as the originating point of a branch to which other nodes connect.

Click icon to add picture

ADVANTAGE

Secondary Hub

•The use of large number of links eliminates network congestion.

•If one link becomes unstable, it does not disable the entire system.

ADVANTAGE

DISADVANTAGE •The amount of required cabling is very large.

•As every node is connected to the other, installation and reconfiguration is very difficult

•The amount of hardware required can make this topology expensive.

MESH Topology

Every node has a point-to-point link to every other node.

Messages sent on a mesh network can take any of several possible paths from source to destination.

Click icon to add picture

NETWORK / COMMUNICATION PROTOCOLSA computer protocol is simply a set of rules and procedures for

transmitting data between two or more devices. They define the manner in which the data communication takes place.

If one computer is sending information to another and they both follow the same protocol, the message gets through; regardless of what type of machines they are and on what operating system they are running.

As long as the machines have software that can manage the protocol, communication is possible.

• Features determined by the protocol are-– How the sending device indicates it has finished sending the

message.– How the receiving device indicates it has received the message.– The type of error checking to be used.

Open Systems Interconnection (OSI) is a basic reference model for communication between 2 end users in a network.

The model lays a framework for the design of network systems that allow for communication across all types of computer systems.

OSI model is a structure that applies (fully or in parts) for any digital communication network.

It is a prescription of characterizing and standardizing the functions of a communication system in terms of abstraction layers.

It consists of separate but related 7 Layers that represent a functional division of the tasks needed to implement a network. They are- Physical, Data Link, Network, Transport, Session, Presentation, Application . Each layer consists of a set of specific protocols.

Similar communication functions are grouped into logical layers. A layer serves the layer above it and is served by the layer below it.

For example- the 4th layer, which provides error-free communications across a network, avails the path needed by applications of 5th layer, while it instructs the 3rd layer to send and receive packets that make up the contents of that path.

NETWORK/COMMUNICATION PROTOCOLS The OSI Model

Categories of the OSI layer:

NETWORK/COMMUNICATION PROTOCOLS The OSI Model

These layers deal with application issues, and are implemented only in the software.

The highest layer- Application, is closest to the end user.These layers handle the data transport issues.The Physical and Data-Link layer are implemented in both hardware and software.Network & Transport layers are implemented only in software.The lowest layer- Physical layer is closest to the cabling and places the information on the cables.

LOWER LAYERS

UPPER LAYERS

Layer Breakdown

Layer 1: Physical– The physical network hardware, medium.

Layer 2: Data Link– How data is organized into frames, and how to

transmit those frames. Byte/bit stuffing, checksums. Layer 3: Network

– How addresses are assigned, and how packets are transmitted from one end of the network to the other.

Layer Breakdown (cont.)

Layer 4: Transport– How to reliably transfer data.

Layer 5: Session– How to start sessions (connections) with remote devices,

machines. (Sockets) Layer 6: Presentation

– How to represent data. Does int, char replacements. Layer 7: Application

– How one user-level program requests a connection to another machine, and how the machine responds.

NETWORK

DEVICES

NETWORKINTERFACECARD (NIC)

HUB

REPEAT

ER

BRIDGE

SWITCH

ROUTER

GATEWAY

MODEM

COMPUTER NETWORK

THE NETWORK DEVICES INTERCONNECT INDIVIDUAL COMPUTERS AND ENSURE THAT THEY COMMUNICATE EFFICIENTLY

NETWORKINTERFACE

CARD (NIC)

•NIC is the first contact between the machine and the network. It connects clients, servers and peripherals to the network via a port.

•They are small circuit boards that can be inserted onto one of the computer motherboard’s slot.

HUB(connectors)•A HUB is a small box that connects individual devices on a

network so that they can communicate with one another.

•The hub's major function is to replicate data it receives from one device attached to it to all others.

•It is also called CONNECTOR, it works on the physical layer of the OSI model.

REPEATER

•A repeater is an electronic device that that operates on the physical layer of the OSI model.

•Signals that carry information within a network can travel a fixed distance before attenuation weakens them enough to be disintegrated. A repeater installed on the link receives the signal, regenerates it, and sends the refreshed copy back to the link.

SWITCH

•Like a hub, a switch too connects individual devices on a network so that they can communicate with one another.

•Switches work on the data link layer of the OSI model.

•They are ‘intelligent’ HUBS. Unlike hubs, network switches can inspect the data packet as they are received, determine the source and the destination device, and forward the packet appropriately.

BRIDGE

•A bridge filters data traffic at a network boundary.

•It reduces the amount of traffic on a LAN by dividing it into segments.

•It inspects incoming traffic and decides whether to forward or discard it.

•Bridges operate at the data link layer of the OSI model.

BRIDGE

ROUTER

•Routers connect two or more networks and forward data packets between them.

•A router creates and/or maintains a table, called a ‘routing table’ that stores the best routes to certain network destinations.

•Router’s sole aim is to trace the best route for information to travel.

Router/firewall

GATEWAY(PROTOCOL CONVERTER

S)

•Gateways are protocol converters. It accepts the packet formatted for one protocol and converts the formatted packet into another protocol.

•It is an internetworking device, which joins two different network protocols together.

•It works on all the 7 layers of the OSI model.

GATEWAY

MODEM

S

An illustration of data sent using a modem and a regular telephone line.

A modem is a device that converts digital data originating from a terminal or computer, to analog signals used by voice communication networks such as the telephone system.

At one end, modems convert the digital pulses to audible tones and convert audio tones back to digital pulses at the other.

The word "Modem" stands for: "Modulator- Demodulator"

Transmission speed

Modems are available in different transmission speeds, which are measured in BPS (bits per second) also called BAUD rate.

Standard modems speeds: 9600 baud, 14400 baud, 28800 baud, 33600 baud, 56800 baud.  

TYPES- Internal/External

Internal modems are electronic cards. An internal modem is installed in one of the computer's expansion slot.

External modems are fully functioning external devices. The external modem is connected to a computer using a serial cable to one of the computer's serial ports, and draws power from an external power source.

THANK YOU

MODEM

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