UNDERSTANDING IMPORTANT UNDERSTANDING IMPORTANT TERMS IN INTERNET TERMS IN INTERNET

PROGRAMMINGPROGRAMMINGbyby

Shahajahan khanShahajahan khanProgramme CoordinatorProgramme Coordinator

Smt. Kamalaben Gambhirchand ShahSmt. Kamalaben Gambhirchand ShahDepartment of Computer ApplicationsDepartment of Computer Applications

HOW DATA IS TRANMITTEDHOW DATA IS TRANMITTED

Data stored in form of binary digits or bits(0’s / Data stored in form of binary digits or bits(0’s / 1’s).1’s).

The digits are coded in accordance with binary The digits are coded in accordance with binary number system.number system.

Data is transmitted between computer using Data is transmitted between computer using electrical or light signals.electrical or light signals.

Data is transmitted in bit per second (bit/s).Data is transmitted in bit per second (bit/s).

TRANSMISSION CHARACTERSTICTRANSMISSION CHARACTERSTIC

The movement of signal over transmission path The movement of signal over transmission path referred to as signal propagation.referred to as signal propagation.

Signals consists of oscillating wave formsSignals consists of oscillating wave forms

The Oscillating signals have The Oscillating signals have following characteristicsfollowing characteristics

Amplitude:Amplitude: Determine the amount of electrical charges Determine the amount of electrical charges inserted on wireinserted on wire

Frequency:Frequency: The number of cycles per unit of time is called the frequency.

Phase :Phase : describes the position of one sound wave relative to another.Bandrate:Bandrate: Band describes rate of change of signal on line Band describes rate of change of signal on line that’s how many time(per second) signal change it pattern.that’s how many time(per second) signal change it pattern.ORORis generally either (1) the amount of data that can be carried from one point to another in a given time period (usually a second)

WHAT IS NETWORKINGWHAT IS NETWORKINGA computer network is a number of computer A computer network is a number of computer (usually called terminals) interconnected by one (usually called terminals) interconnected by one or more transmission paths and sharing resources or more transmission paths and sharing resources like application, hard disk, printer etclike application, hard disk, printer etc

Other definitionOther definition

Network is an arrangement of nodes and Network is an arrangement of nodes and connecting branchesconnecting branches

A configuration of data processing devices at A configuration of data processing devices at software connected for information interchange.software connected for information interchange.

A group of nodes at the links interconnecting A group of nodes at the links interconnecting them. Network consist of a them. Network consist of a ServerServer and and ClientClient or or Client(s)Client(s)

ADVANTAGES OF NETWORKINGADVANTAGES OF NETWORKING

Exchange of data among computers.Exchange of data among computers.

Sharing of resources.Sharing of resources.

Back-up function.Back-up function.

Flexible working environment.Flexible working environment.

WHAT IS NETWAREWHAT IS NETWARE

A software that is used for Networking.A software that is used for Networking.

NETWORK ADMINISTRATORNETWORK ADMINISTRATOR

TASK OF NETWORK ADMINISTRATORTASK OF NETWORK ADMINISTRATOR

Installing and Managing ServersInstalling and Managing Servers Installing and configuring workstationsInstalling and configuring workstations Installing networksInstalling networks Managing users and network securityManaging users and network security Installing shared applicationsInstalling shared applications Providing the user interfaceProviding the user interface Training usersTraining users Managing server resourcesManaging server resources Protecting dataProtecting data Documenting network configurations and proceduresDocumenting network configurations and procedures Resolving user problemsResolving user problems

A person who manages the used and maintenance of A person who manages the used and maintenance of a network.a network.

CLASSIFICATION OF NETWORKSCLASSIFICATION OF NETWORKS

Networks are classified upon the geographical Networks are classified upon the geographical area they span into the following categoriesarea they span into the following categories

i)i) Local Area Network (LAN)Local Area Network (LAN)ii)ii) Wide Area Networking (WAN)Wide Area Networking (WAN)iii)iii) Metropolitan Area Network (MAN)Metropolitan Area Network (MAN)

LOCAL AREA NETWORK (LAN)LOCAL AREA NETWORK (LAN)

A Network consisting of a group of computers and A Network consisting of a group of computers and other devices like printers and modem spread over a other devices like printers and modem spread over a small geographical area is called LAN. The computers small geographical area is called LAN. The computers on a LAN are known as nodes.on a LAN are known as nodes.

ABOUT LANABOUT LAN

Local Area Networks implement Local Area Networks implement shared access shared access technologytechnology. This means that all of the devices . This means that all of the devices attached to the LAN share a single attached to the LAN share a single communications communications mediummedium, usually a coaxial, , usually a coaxial, twisted-pair, fiber-optic cable etc.twisted-pair, fiber-optic cable etc.

A physical connection to the network is made by A physical connection to the network is made by putting a putting a network interface cardnetwork interface card (NIC) inside the (NIC) inside the computer and connecting it to the network cable. computer and connecting it to the network cable. Once the physical connection is in place, the Once the physical connection is in place, the network software manages communications network software manages communications between stations on the network. between stations on the network.

ABOUT CABLEABOUT CABLECoaxial CableCoaxial Cable (Similar to cable TV wires), (Similar to cable TV wires), A cable consisting of one conductor (condenser) usually a A cable consisting of one conductor (condenser) usually a small copper tube or wire with in an insulator from another small copper tube or wire with in an insulator from another conductor of larger diameter.conductor of larger diameter.

Two kinds of coaxial CableTwo kinds of coaxial Cable• 50 Ohm cable, which is used for digital transmission and 50 Ohm cable, which is used for digital transmission and

is called base band coaxial cable.is called base band coaxial cable.

• 75 Ohm cable, which is used for analog transmission and 75 Ohm cable, which is used for analog transmission and is called the broadband coaxial cableis called the broadband coaxial cable

Data rate of 10mbps. Higher data rates are possible in Data rate of 10mbps. Higher data rates are possible in shorter cable longer cable can also be used, but only at shorter cable longer cable can also be used, but only at lower data rates.lower data rates.

Coaxial cable used forCoaxial cable used for-Local area networkLocal area network-Long distance transmission within telephone systemLong distance transmission within telephone system

ABOUT CABLEABOUT CABLEtwisted-pairtwisted-pair (Similar to telephone wires), (Similar to telephone wires),A twister – pairs cables can transmit data at 10 Mbps (10 A twister – pairs cables can transmit data at 10 Mbps (10 million bits per second)million bits per second)

Advantages•It is a thin, flexible cable that is easy to string between walls.

•Because UTP is small, it does not quickly fill up wiring ducts.

•UTP costs less per foot than any other type of LAN cable.

ABOUT CABLEABOUT CABLEFiber-optic cableFiber-optic cable (are used for higher speeds and (are used for higher speeds and greater distances than copper wires are capable greater distances than copper wires are capable of providing).of providing).

The fiber – optics cable extends the distance to The fiber – optics cable extends the distance to 2,000 meter over multi-mode cable.2,000 meter over multi-mode cable.

Fiber – optics cables can transmit data at 10 Fiber – optics cables can transmit data at 10 Gigabit.Gigabit.

WORKING OF LANWORKING OF LAN

To send messages to and from computers, the network software puts To send messages to and from computers, the network software puts the message information in a the message information in a packetpacket. (If the message to be sent is too . (If the message to be sent is too big to fit into one packet, it will be sent in a series of packets.) In big to fit into one packet, it will be sent in a series of packets.) In addition to the message data, the packet contains a addition to the message data, the packet contains a headerheader and a and a trailertrailer that carry special information to the destination. One piece of that carry special information to the destination. One piece of information in the header is the information in the header is the addressaddress of the destination. of the destination.

The NIC transmits the packet onto the LAN as a stream of data The NIC transmits the packet onto the LAN as a stream of data represented by changes in electrical signals. As it travels along the represented by changes in electrical signals. As it travels along the shared cable, each NIC checks its destination address to determine if shared cable, each NIC checks its destination address to determine if the packet is addressed to it. When the packet arrives at the proper the packet is addressed to it. When the packet arrives at the proper address, the NIC copies it and gives its data to the computer. Since address, the NIC copies it and gives its data to the computer. Since each individual packet is small, it takes very little time to travel to the each individual packet is small, it takes very little time to travel to the ends of the cable. After a packet carrying one message passes along ends of the cable. After a packet carrying one message passes along the cable, another station can send its packet. In this way, many the cable, another station can send its packet. In this way, many devices can share the same LAN medium. devices can share the same LAN medium.

CHARACTERISTICS OF LANCHARACTERISTICS OF LAN

A LAN exists within a small geographical area, like a room, or A LAN exists within a small geographical area, like a room, or a single floor of a building or within the same building.a single floor of a building or within the same building.

LAN nodes communicate at high speed, between 4 – 100 LAN nodes communicate at high speed, between 4 – 100 MBPS (Mega Byes / Sec.)MBPS (Mega Byes / Sec.)

It is a privately owned network. Complete ownership is with a It is a privately owned network. Complete ownership is with a single organization.single organization.

Diameter of not more than few kilometers i.e. it should not Diameter of not more than few kilometers i.e. it should not exceed 2 – 3 K.M.exceed 2 – 3 K.M.

LAN normally has fewer nodes, about 500.LAN normally has fewer nodes, about 500.

CHARACTERISTICS OF LANCHARACTERISTICS OF LAN

It has a simple technology and does not require much It has a simple technology and does not require much specialized equipment.specialized equipment.

Adding a node does not significantly reduce LAN performance.Adding a node does not significantly reduce LAN performance.

ADVANTAGES OF LANADVANTAGES OF LAN

Workstations can share peripheral devices like printers. This Workstations can share peripheral devices like printers. This cheaper than buying a printer for every workstation. cheaper than buying a printer for every workstation.

Workstations do not necessarily need their own hard disk or Workstations do not necessarily need their own hard disk or CD-ROM drives which make them cheaper to buy than stand-CD-ROM drives which make them cheaper to buy than stand-alone PCs.alone PCs.

User can save their work centrally on the network’s file User can save their work centrally on the network’s file server. This means that they can retrieve their work from any server. This means that they can retrieve their work from any workstation on the network. They don’t need to go back to the workstation on the network. They don’t need to go back to the same workstation all the time. same workstation all the time.

Users can communicate with each other and transfer data Users can communicate with each other and transfer data between workstations very easily. between workstations very easily.

ADVANTAGES OF LANADVANTAGES OF LAN

One copy of each application package such as a word One copy of each application package such as a word processor, spreadsheet etc. can be loaded onto the file and processor, spreadsheet etc. can be loaded onto the file and shared by all users. When a new version comes out, it only shared by all users. When a new version comes out, it only has to be loaded onto the server instead of onto every has to be loaded onto the server instead of onto every workstation. workstation.

DISADVANTAGES OF LANDISADVANTAGES OF LAN

Special security measures are needed to stop users Special security measures are needed to stop users from using programs and data that they should not from using programs and data that they should not have access to.have access to.

Networks are difficult to set up and need to be Networks are difficult to set up and need to be

maintained by skilled technicians. maintained by skilled technicians.

If the file server develops a serious fault, all the If the file server develops a serious fault, all the users are affected, rather than just one user in the users are affected, rather than just one user in the case of a stand-alone machine. case of a stand-alone machine.

BusBus RingRing StarStar

VARIOUS TOPOLOGYVARIOUS TOPOLOGY

BUSBUS

ADVANTAGES OF THE BUSADVANTAGES OF THE BUSThere are several advantages to a bus topology.There are several advantages to a bus topology.

The bus is simple, reliable in very small networks, easy to use, and The bus is simple, reliable in very small networks, easy to use, and easy to understand.easy to understand.

The bus requires the least amount of cable to connect the computers The bus requires the least amount of cable to connect the computers together and is therefore less expensive than other cabling together and is therefore less expensive than other cabling arrangementsarrangements

It is easy to extend a bus. Two cable can be joined into one larger It is easy to extend a bus. Two cable can be joined into one larger cable with a BNC() barrel connector, making a long cable and allowing cable with a BNC() barrel connector, making a long cable and allowing move computers to join the networkmove computers to join the network

A repeater can also be used to extend a bus, a repeater boost the A repeater can also be used to extend a bus, a repeater boost the signal and allows it to travel a longer distancesignal and allows it to travel a longer distance

DISADVANTAGESDISADVANTAGES OF THE BUSOF THE BUSA bus topology is commonly subject to the following disadvantagesA bus topology is commonly subject to the following disadvantages

Heavy network traffic can slow a bus considerably. Because any Heavy network traffic can slow a bus considerably. Because any computer can transmit at any time and computers on most bus computer can transmit at any time and computers on most bus networks do not coordinate a bus network with a lot of computers can networks do not coordinate a bus network with a lot of computers can spend a lot of its bandwidth (capacity for transmitting information) spend a lot of its bandwidth (capacity for transmitting information) with the computers interrupting each other instead of communication. with the computers interrupting each other instead of communication. The problem only gets worse as more computers are to the network.The problem only gets worse as more computers are to the network.

Each barrel connectors weakens the each signal and to many may Each barrel connectors weakens the each signal and to many may prevent the signal from being correctly received all along the busprevent the signal from being correctly received all along the bus

It is difficult to troubleshoot a bus. A cable break or malfunctioning It is difficult to troubleshoot a bus. A cable break or malfunctioning anywhere between two computer can cause them not to be able to anywhere between two computer can cause them not to be able to communicate with each other. A cable break or loose connector will communicate with each other. A cable break or loose connector will also cause reflections and bring down the whole network, causing all also cause reflections and bring down the whole network, causing all network activity to stop.network activity to stop.

RINGRING

A second type of broadcast system is the ring. In a ring, each bit A second type of broadcast system is the ring. In a ring, each bit propagates a round on its own not waiting for the next of the propagates a round on its own not waiting for the next of the packet to which it belongs. packet to which it belongs.

In ring topology, each computer is connected to the next In ring topology, each computer is connected to the next computer, with the last one connected to the first.computer, with the last one connected to the first.

ADVANTAGESADVANTAGES OF THE RINGOF THE RINGThe ring topology offers the following advantages :The ring topology offers the following advantages :

Because every computer is given canal access to the token, no Because every computer is given canal access to the token, no one computer can monopolize the network.one computer can monopolize the network.

The fair sharing of the network allows the network to degrade The fair sharing of the network allows the network to degrade gracefully (continue to function in a useful, if slower, manner, gracefully (continue to function in a useful, if slower, manner, rather than fail once capacity is exceeded) as more users are rather than fail once capacity is exceeded) as more users are added.added.

DISADVANTAGES OF THE RINGDISADVANTAGES OF THE RING

The ring topology has the following disadvantages : The ring topology has the following disadvantages :

Failure of one computer on the ring can affect the whole Failure of one computer on the ring can affect the whole networknetwork

It is difficult to troubleshoot a ring networkIt is difficult to troubleshoot a ring network

Adding or removing computers disrupts the networksAdding or removing computers disrupts the networks

STARSTAR

A third type of broadcast system is the star A third type of broadcast system is the star Each computer on a star network communicate with a central Each computer on a star network communicate with a central hub that resends the messages either to all the computers or hub that resends the messages either to all the computers or only to the destination computer. The hub in a broadcast star only to the destination computer. The hub in a broadcast star network can be active or passivenetwork can be active or passive

An active hub regenerates the electrical signal and send it to An active hub regenerates the electrical signal and send it to all the computers connected to it. This type of hub is often all the computers connected to it. This type of hub is often called a multiport repeater. Active hubs and switches called a multiport repeater. Active hubs and switches electrical power to run. A passive hub, such as wiring panels electrical power to run. A passive hub, such as wiring panels or punch- down blocks, merely as a connection point and or punch- down blocks, merely as a connection point and does not amplify or regenerate the signal passive hubs do not does not amplify or regenerate the signal passive hubs do not require electric power to runrequire electric power to run

ADVANTAGESADVANTAGES OF THE STAROF THE STAR It is easy to modify and add new computers to a star network It is easy to modify and add new computers to a star network

without disturbing the rest of the network. You simply run a new without disturbing the rest of the network. You simply run a new line from the computer to the central location and plug into the hub. line from the computer to the central location and plug into the hub. When the capacity of the central hub is exceeded, you can replace When the capacity of the central hub is exceeded, you can replace it with one that has a larger number of ports to plug lines intoit with one that has a larger number of ports to plug lines into

The center of a star network is a good place to diagnose network The center of a star network is a good place to diagnose network faults. Intelligent hubs (hubs with micro processors that implement faults. Intelligent hubs (hubs with micro processors that implement features in addition to repeating network signals) also provide for features in addition to repeating network signals) also provide for centralized monitoring and management of the network.centralized monitoring and management of the network.

Single computer failures do not necessarily bring down the whole Single computer failures do not necessarily bring down the whole star network. The hub can detect a network far it and isolate the star network. The hub can detect a network far it and isolate the offending computer or network cable and allow the rest of the offending computer or network cable and allow the rest of the network to continue operatingnetwork to continue operating

You can use several cable type in the same network with a hub that You can use several cable type in the same network with a hub that can accommodate multiple cable typescan accommodate multiple cable types

A hybrid hub can accommodate several types of cable in the same A hybrid hub can accommodate several types of cable in the same star network.star network.

WIDE AREA NETWORK (WAN)WIDE AREA NETWORK (WAN)A Wide Area Network (WAN) is a computer network A Wide Area Network (WAN) is a computer network used to exchange information over a wide used to exchange information over a wide geographical area. It can be situated within several geographical area. It can be situated within several countries or even worldwide. Larger than a LAN, it can countries or even worldwide. Larger than a LAN, it can use phone lines or satellites as transmission media. In use phone lines or satellites as transmission media. In some cases, linking together some LANs forms a some cases, linking together some LANs forms a WAN.WAN.

When networks connect to form a bigger network (a When networks connect to form a bigger network (a bigger WAN), the resulting network is called an bigger WAN), the resulting network is called an internetwork, which is generically abbreviated to ‘an internetwork, which is generically abbreviated to ‘an internet’. Now when all WANs in the world connect internet’. Now when all WANs in the world connect forming a global internet, we call it The Internet, forming a global internet, we call it The Internet, which everyone knows! That’s why the Internet is which everyone knows! That’s why the Internet is always written with a capital I. It is the biggest WAN always written with a capital I. It is the biggest WAN we have.we have.

IMPORTANCE AND ADVANTAGES IMPORTANCE AND ADVANTAGES OF WANOF WAN

Two great advantages of WAN are allowing Two great advantages of WAN are allowing securesecure and and fastfast data transmission between the different data transmission between the different nodes in the network. The data transmission is also nodes in the network. The data transmission is also reliable and inexpensive.reliable and inexpensive.

    Big organizations and companies, which have Big organizations and companies, which have several branches all over the world, are the ones several branches all over the world, are the ones who greatly benefit from WANs, as WANs enable who greatly benefit from WANs, as WANs enable them to easily communicate with their partners or them to easily communicate with their partners or employees around the globe. WAN have had a employees around the globe. WAN have had a great impact on e-business, which has became so great impact on e-business, which has became so popular in this Internet age.popular in this Internet age.

Most of the time, public telecommunications Most of the time, public telecommunications companies in different countries manage, control companies in different countries manage, control and maintain WANs. They also provide WAN users and maintain WANs. They also provide WAN users with various services such as leased lines. with various services such as leased lines.

METROPOLITAN AREA NETWORK METROPOLITAN AREA NETWORK (MAN)(MAN)

In between LAN & WAN is MANIn between LAN & WAN is MAN

DIFFERENCE BETWEEN LAN, WAN DIFFERENCE BETWEEN LAN, WAN AND MANAND MAN

LANLAN WANWAN MANMANSet up in a Set up in a restricted restricted geographical areageographical area

It is worldwideIt is worldwide MAN is with in the MAN is with in the citycity

LAN use cablesLAN use cables WAN uses Modem / WAN uses Modem / SatellitesSatellites

MAN uses ModemsMAN uses Modems

It is privately It is privately ownedowned

Government own a Government own a WANWAN

Fewer nodes are Fewer nodes are connected to LANconnected to LAN

Many nodes are Many nodes are connected to WANconnected to WAN

LAN technology is LAN technology is relatively simplerelatively simple

WAN uses complex WAN uses complex technologytechnology

LAN is a digital LAN is a digital networknetwork

WAN transmission WAN transmission is digital as well as is digital as well as analoganalog

HUBSHUBS

Hubs Hubs (also referred to as (also referred to as repeatersrepeaters or or concentratorsconcentrators) are a ) are a very important part of the networking process. Hubs are wiring very important part of the networking process. Hubs are wiring concentrators, which make use of concentrators, which make use of structured wiringstructured wiring to connect to connect stations on a LAN. They contain user ports into which each stations on a LAN. They contain user ports into which each station's cable is connected. Many hubs are called station's cable is connected. Many hubs are called intelligentintelligent, or , or manageablemanageable, which means that each of the ports on the hub can , which means that each of the ports on the hub can be configured, monitored, enabled, and disabled by a network be configured, monitored, enabled, and disabled by a network operator from a hub management console.operator from a hub management console.

All of these hubs can be linked together to broaden the network. In order to create an internetwork (linking LANs together), other more complex devices are used.

• Bridge - device that connects two or more networks and forwards packets among them. Usually, bridges operate at the physical network level. For example, an Ethernet bridge connects two physical Ethernet cables and forwards from one cable to the other exactly those packets that are not local. Bridges differ from repeaters because bridges store and forward complete packets while repeaters forward electrical signals. They differ from IP Gateways or IP Routers because they use physical addresses instead of IP addresses.

• Routers - use Network Layer Protocol Information within each packet to route it from one LAN to another. This means that a router must be able to recognize all of the different Network Layer Protocols that may be used on the networks it is linking together.

• Switches - devices with multiple ports, each of which can support an entire Ethernet, FDDI or Token Ring segment. With a different segment connected to each of the ports, it can switch packets between them as needed. In effect, a switch acts like a very fast multi-port bridge because packets are filtered based on the destination address. A new network technology, called Asynchronous Transfer Mode (ATM), is based on the switch concept.

What Is Wi-FiWhat Is Wi-FiA wireless network uses radio waves, just like cell phones, A wireless network uses radio waves, just like cell phones, televisions and radios do. In fact, communication across a televisions and radios do. In fact, communication across a wireless network is a lot like two-way radio communication. wireless network is a lot like two-way radio communication. Here's what happens: Here's what happens: A computer's wireless adapter translates data into a radio signal A computer's wireless adapter translates data into a radio signal and transmits it using an antenna. and transmits it using an antenna. A wireless router receives the signal and decodes it. The router A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired sends the information to the Internet using a physical, wired Ethernet connection. Ethernet connection.

The process also works in reverse, with the router receiving The process also works in reverse, with the router receiving information from the Internet, translating it into a radio signal and information from the Internet, translating it into a radio signal and sending it to the computer's wireless adapter. The radios used for sending it to the computer's wireless adapter. The radios used for WiFi communication are very similar to the radios used for walkie-WiFi communication are very similar to the radios used for walkie-talkies, cell phones and other devices. They can transmit and talkies, cell phones and other devices. They can transmit and receive radio waves, and they can convert 1s and 0s into radio receive radio waves, and they can convert 1s and 0s into radio waves and convert the radio waves back into 1s and 0s.waves and convert the radio waves back into 1s and 0s.

WiFi has a lot of advantages. Wireless networks are easy to set WiFi has a lot of advantages. Wireless networks are easy to set up and inexpensive.up and inexpensive.