Chapter No 1
When one or more than one computer are connected with each other for the purpose of sharing information and share resources (such as printers and CDs), exchange files, or allow electronic communications is called Network. The entire computer in the network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
Following are different type of Computer Network
The network in a single building or some group of building is called local area network. Generally we sat that the network which is established relatively small area is called local area network. For example network in a lab, in schools and in a building. The smallest LAN may only use two computers, while larger LANs can accommodate thousands of computers. A LAN typically relies mostly on wired connections for increased speed and security, but wireless connections can also be part of a LAN. High speed and relatively low cost are the defining characteristics of LANs.
A wide area network, or WAN, occupies a very large area, such as an entire country or the entire world. A WAN can contain multiple smaller networks, such as LANs or MANs. The Internet is the best-known example of a public WAN. We say collection of more than one network on relatively large aria is called wide area network.
A metropolitan area network, or MAN, consists of a computer network across an entire city, college campus or small region. A MAN is larger than a LAN, which is typically limited to a single building or site. Depending on the configuration, this type of network can cover an area from several miles to tens of miles. A MAN is often used to connect several LANs together to form a bigger network.
WLANs provide wireless network communication over short distances using radio or infrared signals instead of traditional network cabling. These types of networks don’t require that devices rely on physical cables to connect to the network. A WLAN typically extends an existing wired local area network. For example Mobile User is Connected Through Wi-Fi with local area network.
When two or more than two geographically separate computer networks connected through wireless link, including infrared, satellite, and radio signals. The cellular towers transmit a wireless signal over a range of several miles to a mobile device connect to internet.
The connection of different company office branches or different division are called Enterprise network. The purpose of an enterprise network is to provide security by stopping isolated users and workgroups and should be able to maintain and provide performance and reliability.
A global network is any communication network which spans the entire Earth. A global area network (GAN) basically composed of different interconnected networks that cover an unlimited geographical area. Internets, broadband GAN, GSM (Global System for Mobile Communication) are some example of Global Networks.
A personal area network, or PAN, is a computer network organized around an individual person within a single building. This could be inside a small office or residence. A typical PAN would include one or more computers, telephones, peripheral devices, video game consoles and other personal entertainment devices.
1) File Sharing: - You can easily share data between different users, or access it remotely if you keep it on other connected devices. We can also share the Hardware like that printer, DVD etc.
2) Software Cost and Management: - Networking manages the overall cost of the administration by sharing the software and hardware.
3) Sharing a single internet connection: - If you have only one connection of internet at your home or office then with the help of networking you can use same connection on all of your computer and devices.
4) Resource Sharing: - All computers in the network can share resources such as printers, fax machines, modems, and scanners.
5) Flexible Access: - Networks allow their users to access files from computers throughout the network. This means that a user can begin work on a project on one computer and finish up on another. Multiple users can also collaborate on the same project through the network.
6) Desk Top Sharing: - With the Help of Networking you can access other computer remotely other place.
Peer-to-peer networks
Peer-to-Peer network is a network which is established without dedicating server. All the computer on the network may be server and may be client some time. All the computer work independently and the directory information such that user and password information separately store on each computer.
Advantages of peer networks
Disadvantages of peer-to-pee
Server Base Network
It is a important concept for networking. Server is a system which shares the resources on the network for client system. When a client link to server its check the security rule and give permission to client. Clients request Services such as file the server delivers Storage and Printing. The organization who want to store the data centrally and then access from different location use server system.
Advantages of server based networks
Disadvantages of server based networks
The information in raw form is called data. So we say that the measurement, number, quantities, characters, or symbols on which operations are performed by a computer and may be stored on media. Data can also be defined as any fact and figure is called data.
Types of Data
When we talk about data communication then there are basically two types of data is used.
Analog data
The data which is represented in a physical way and representing by physical properties and can be express any value along a continuous scale is called analog data. The analogue clock is simple example of analog data where change is continues. Sound ways is also example if analog data.
Digital data
A discrete and discontinuous representation of information is called digital data. The most electronic devices such as Computers, cameras, mobile phones stored and processed the data inform of number is called digital data. These numbers are in form of binary number means that 0 and 1 which represent the switches On or OFF. For example when we store the audio data in the form of ones and zeros. The audio device such as CD Player , read these ones and zeros and translate into actual signals. Computer software is a collection of numeric codes which tell the computer what to do this is also an example of digital data.
The data transfer rate (DTR) is the amount of digital data that is moved from one place to another in a given time. The data transfer rate can be viewed as the speed of travel of a given amount of data from one place to another. In general, the greater the bandwidth of a given path, the higher the data transfer rate. In telecommunications, data transfer is usually measured in bits per second. For example, a typical low-speed connection to the Internet may be 33.6 kilobits per second (Kbps).
The baud rate is the rate which is used for the communication purpose and it is used to identify that how much of the data had been transferred but at how much speed. The rate indicates the number of electrical oscillations (regular variation) per second that occurs within a data transmission. The higher the baud rate, the more bits per second that are transferred.
Chapter No 2
Network topology means the physical or logical layout of a network in which define how the different nodes are placed and interconnected with each other and also describe how the data is transferred between these nodes.
In this topology each of the devices and computers on a network connect to a central hub / switch. A major disadvantage of this type of network topology is that if the central hub fails, all computers connected to that hub would be disconnected. All information on a star network first passes through the hub or switch before continuing to its destination. It also acts as a repeater for the data flow. Mostly we use twisted pair cable to connect the entire computer with central device but we can also use coaxial or fiber optical cable.
Advantages of Star Topology
Disadvantages of Star Topology
In Ring topology all the devices or computer are connected to each other in a circular shape. All the data which will be send move around the ring until it reaches its final destination.
Advantages of Ring Topology
There is no need for network server to control the connectivity between workstations.
Disadvantage of Ring Topology
In This topology all the computer and devices are connected to a single cable. This is typically use in a small networks and take the advantage of using less cable. Their main disadvantage is that if any segment of the network fails, all transmissions do as well.
Advantages of bus topology
Disadvantages of Bus Topology
Tree topology
In tree topology more than two hubs are connected each other this topology is collection of linear bus and star topology. The Each star network is a local area network with central computer or server and the entire node direct ally link to this server and the central computers or server of the star networks are connected to a main cable called the bus.
Advantages of Tree topology
Disadvantages of Tree topology
In a mesh network topology, each of the network node, computer and other devices, are interconnected with one another, allowing for most of the transmission to be distributed , even if one of the connection go down. This type of topology is very expensive as there are many redundant connections, thus it is not mostly used in computer networks. It is commonly used in wireless networks.
Advantages of Mesh topology
Disadvantages of Mesh topology
Chapter No 3
The objects basically used in computer network are known as Computer Network Elements. Following are the basic elements of Computer Network:
1) Sending and Receiving Terminal:
Terminal is a computer or other equipment that allow a user to input data into a system and also receive data over computer communication lines.
2) Protocols:
Protocols are some defined rules and conventions for communication between network devices. Network protocols include mechanisms for devices to identify and make connections with each other, as well as formatting rules that specify how data is packaged into sent and received messages.
3) Software:
Network software is a foundational element for any network. This type of software helps administrators deploy, manage and monitor a network. The traditional networks are made up of specialized hardware, such as routers and switches, that bundle the networking software into the solution.
4) Hardware:
Communication medium and other devices which are use for interconnecting and transmission purpose are the computer Network Hardware, for example NIC, Switch etc.
Different components of a local area network are as follows:
Communication media is used to transfer data from one computer to another computer. Low-cost LANs are connected with twisted wire pair. Many LANs use coaxial or fiber-optic cables. Some LANs use wireless transmission media.
NIC stands for network interface card. It is also known as network adapter. A network interface card is a device that physically connects each computer to a network.
Terminal is a computer or other devices which are connected with in Local area Network. Terminal may be a Server and Workstation. Where Server share the resources and Workstation Use these resources.
A Hub / Switch is a common connection point for devices in a network. Hubs / Switch contain more than one port. The all the computer are connected on that port when we send the data to any computer to other computer then in Hub its switch from one port to destination port.
Protocols are some defined rules and conventions for communication between network devices. Network protocols include mechanisms for devices to identify and make connections with each other, as well as formatting rules that specify how data is packaged into sent and received messages.
Once the physical building blocks of the LAN are put into place, the next step is to make them functional. Software is needed for devices to function cooperatively and effectively on the LAN.
Modem:
Modem short for modulator-demodulator. In communication modem converts the digital data in to analog so that it transmits over the phone line because phone line transmits analog data. in the same way on the other hand when data is received modem again convert this analog data in to digital single so that computer store and process on this information.
Types of Modem
1) INTERNAL MODEM
2) EXTERNAL MODEM
3) FAX MODEM
4) DIAL UP MODEM
5) DSL MODEM
6) ISDN MODEMS
7) AUTO ANSWER MODEM
1) INTERNAL MODEM:
An internal modem or on-board modem is a type of modem which is installed on the slots of mother board. This modem is an expansion card.
2) EXTERNAL MODEM:
External modem is a removable device which is used for communication purpose. This type of modem is externally connected with computer with COM Port or USB port and has some lights which indicate the processing status.
3) FAX MODEM
Fax modem enables a computer to transmit and receive documents on a telephone line normally called Fax. With a fax modem a Computer perform like a Fax Machine.
4) DIAL UP MODEM:
Dial-up reference to a telephone connection in a system of many lines shared by many users. Dial-up modems use traditional copper phone lines to transmit analog signals that are classified according to the modulation standards outlined.
5) DSL MODEM
DSL (digital subscriber line) modem also called broadband modem is used for providing broadband service to different kind of Internet connection. This modem transmits height speed data. DSL modems are suitable for high speed internet and data transfer over ordinary phone line.
6) ISDN MODEMS
ISDN stand for Integrated Services for Digital Network is a type of communication standards for simultaneous digital transmission of voice, video data over single wire or optical fiber. It can operate over a stander telephone, wires or other media. It is completely digital in a nature from one end of the connection to another.
7) AUTO ANSWER MODEM
By this modem your computer can receive telephone calls in your absence. It is necessary when your computer service that people use for calls. In auto-answer mode, MODEM attempts to establish a connection whenever the telephone rings. Auto-answer is also a critical feature for fax modems because it enables you to receive fax documents while you are away. All fax machines are auto-answer.
An access point is a wireless network device that acts as a portal for devices to connect to a local area network. Access points are used for extending the wireless coverage of an existing network and for increasing the number of users that can connect to it.
A high-speed Ethernet cable runs from a router to an access point, which transforms the wired signal into a wireless one. Wireless connectivity is typically the only available option for access points, establishing links with end-devices using Wi-Fi.
A Hub is a common connection point for devices in a network. Hubs contain more then one ports. The all the computer are connected on that port when we send the data to any computer to other computer then in Hub its switch from one port to destination port.
There are three main types of hub:
1) Passive hub:
A passive hub simply combines the signals of the network segment. It does not provide any processing or regeneration of signals. when any one send the data then Each computer can receive the signal to all computers connected to the hub.
2) Active hub:
Active hub is a central connecting device such as a computer or router that not only provides connectivity but also regenerates and retransmits the signals sent through it and send to proper destination.
3) Intelligent hub:
This hub also work like active hub and also have some extra features as compare to active hub for example network management, bridging, routing and switching. This intelligent hub gives the remote monitoring and management through Simple Network Management Protocol (SNMP). Which provide:
Repeater is a hardware device, which is used to extend LAN. When the distance of local area network is to long then we use a special device repeater which Receive analog data and convert to digital data and the regenerate a new clean analog signal. The repeater connects directly to the cable. The maximum size of LAN is 500 meter so we can increase this size by using a pair of repeater by connecting each LAN segment to make a network, 1500 meter long.
The bridge is a hardware that connects a LAN to LAN that uses the same protocol. The function of Bridges is its filter and reduced the traffic. For example when a message is send from any computer then its decides whether a message from you to someone else is going to the local area network or other local area network.
Router is device which connect two networks for example local network and internet. Routers determine whether the source and destination are on the same network or whether data must be transferred from one network type to another. Routers contain software called firmware for example it contains DHCP which provide IP address to all connected device. Router is also providing the facility of Switch or Hub. Router is also use as access point. For example, routers are commonly used in home networks to share a single Internet connection between multiple computers through cable or wirelessly through Wi-Fi.
Gateway is a network point that acts as an entrance to another network. When router routing the information from one network to another network then gateway specify the exits point and when any information is coming from another network then gateway is entry point. for example a device which is provide from ISP for internet service is a getaway which create exist and entry point to next network.
The means from which information is transmitted are called communication media. There are different media are used for transmitting data from one place to another place.
The following are the two major types of communication media are:
Cable is the medium of communication through which information usually moves from one device to another device within one network or different network. There are several types of cable, which are commonly used for communication. The type of cable chosen for a network is depending on your topology, protocol, and size of network.
Cable media consist of:
1) Twisted Pair Cables
Twisted Pair cable consists of two independently insulated wires twisted around one another. The purpose of two wires twisted together is reducing crosstalk and electromagnetic induction. Twisted pair cable is used in telephone network and also local aria computer networking at home and much company. There are two type of Twisted Pair cable are available:
(a) Shielded Pair Cable (STP): Some time twisted pair insolated with a special kind of copper surrounding the wires to protect the transmission.
Unshielded Pair Cable (UTP): Unshielded twisted Pair cable (UTP) consists of a number of twisted pairs with a simple plastic casing. This cable is commonly use for local area networking due to less expensive.
2) Coaxial Cable
Coaxial cable was invented in 1929 and first used on commercial basics in 1941. Coaxial cable consists of a center wire surrounded by insulation and then outer channel used as ground. The shield minimizes electrical and radio frequency interference. Coaxial cable is used by cable TV companies between the community antenna and user homes and businesses. This cable can carry information for a great distance.
Advantages
Disadvantages:
3) Fiber optical cables
Fiber Optical cable containing more than one optical glass that carry the signal in shape of light. Each of the glass are individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed. Optical fiber transmits light rather than electronic signals eliminating the problem of electrical interference. This makes it ideal for certain environments that contain a large amount of electrical interference. Fiber optic cable has the ability to transmit signals over much longer distances than coaxial and twisted pair. The optical fiber carry the information with greater speeds.
Advantages of Fiber Optical
Disadvantages
When it is impossible to install wires and cables or cabling is expensive then you can use Wireless Medias. Wireless media generate higher electromagnetic frequency, such as radio wave, microwave and infrared. They transmit signal over a long distance. In wireless transmission, various types of electromagnetic waves are used to transmit signal. For example Radio satellite transmission visible light, infrared light, x- rays and gamma rays.
Wireless media consist of:
The radio wave one of the types of wireless media which transmit the signal through the air, often over millions of miles. In this transmission electromagnetic (radio) energy travels from a transmitting antenna to a receiving antenna. It is used for the radio and TV program for the portable phone. The computer data also transmitted in the form of radio waves. It does not require a direct physical connection between computers. Each computer attach to an antenna which transmit and receive radio frequency.
Types of Radio Waves
2) Micro wave transmission
Microwave transmission transmits the signal via radio using a series of microwave towers. Microwave Communication is the most common wireless communication medium and is spread widely across the world. The wireless access points and wireless devices work on microwave communication. This communication medium widely used in computers and also cellular communication as well.
3) Infrared Transmission:
Infrared radiation IR is electromagnetic radiation which is used for medium and short range communications. Infrared communication device use infrared light beams to transmit signal. Infrared is one of the most primitive forms of wireless communication. Infrared Networks need to have the two devices in line with each other with an angle of +_15 degrees. With infrared transmission, computers can transfer files and other digital data bidirectional.
1) RJ-45 Connector:
The RJ-45 connector is mostly used for network cabling and for telephony applications. RJ-45 can also used for serial connections in computer devices. This connector used for 10Base-T and 100Base-TX Ethernet connections.
2) RJ-11 Connector:
RJ-11 is abbreviation of Registered Jack – 11, used in telephone set. The RJ-11 connects the telephone set to telephone line and also telephone hand receiver to telephone set. The RJ-11 can also be used in some type of local area network. RJ-11 used 4 or 6 twisted pair cable.
3) BNC Connector:
Short for Bayonet connector. This type of connector used with coaxial cables such as the RG-58 cable used with the 10Base-2 Ethernet system. This connector has a center pin connected to the center cable conductor and a metal tube connected to the outer cable shield. A rotating ring outside the tube locks the cable to any female connector.
BNC connectors can also be used to connect some monitors, which increases the accuracy of the signals sent from the video adapter.
Chapter No 5
OSI seven-layer model
The OSI is abbreviation of Open System Interconnection. The OSI model defines how network protocol works it’s describe complete networking framework to implement protocols in seven layers. The major purpose of the OSI reference model is to guide vendors and developers who develop digital communication products and software programs. So that they create will interoperate, and to facilitate clear comparisons among communications tools.
Following are the seven layer of OSI Module:
7. Application Layer
The Application Layer is the one at the top. It’s what most users see. In the OSI model, this is the layer that is the “closest to the end user”. Web browser (Google Chrome, Firefox, Safari, etc.) or other app - Skype, Outlook, Office - are examples of Layer 7 applications.
Presentation layer represents the preparation or translation of application format to network format, or from network formatting to application format. In other words, the layer “presents” data for the application or the network. A good example of this is encryption and decryption of data for secure transmission
When two devices, computers or servers need to “speak” with one another, a session needs to be created, and this is done at the Session Layer. Functions at this layer involve setup, coordination (how long should a system wait for a response, for example) and termination between the applications at each end of the session.
Transport layer work under the Network Layer. Network layer set the logical path between sender and receiver and Transport layer transparently transfer the data between end systems. So this layer is end-to-end communication over a network. This layer is also responsible for the management of error correction, providing quality and reliability to the end user.
This layer is responsible for packet forwarding, including routing through different routers. You might know that your Boston computer wants to connect to a server in California, but there are millions of different paths to take. Routers at this layer help do this efficiently.
The Data Link Layer provides node-to-node data transfer (between two directly connected nodes), and also handles error correction from the physical layer. Two sub layers exist here as well - the Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. In the networking world, most switches operate at Layer 2.
Physical Layer is bottom layer, which represents the electrical and physical representation of the system. This can include everything from the cable type, radio frequency link, as well as the layout of pins, voltages and other physical requirements. When a networking problem occurs, many networking pros go right to the physical layer to check that all of the cables are properly connected and that the power plug hasn’t been pulled from the router, switch or computer, for example.
Chapter No 6
IP is an abbreviation for Internet Protocol. The IP identify a single computer on TCP/IP Network. In network a name identify the computer and IP identify the address of computer means where is this computer. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255. For example, 912.168.1.1 could be an IP address. Within an isolated network, you can assign IP addresses at random as long as each one is unique. However, connecting a private network to the Internet requires using registered IP addresses (called Internet addresses) to avoid duplicates.
Following three IP address classes are used in TCP/IP Network.
Class A - supports 16 million hosts on each of 126 networks
Class B - supports 65,000 hosts on each of 16,000 networks
Class C - supports 254 hosts on each of 2 million networks
|
ss |
Starting IP Address |
Ending IP Address |
|
A |
10.0.0.0 |
10.255.255.255 |
|
B |
172.16.0.0 |
172.31.255.255 |
|
C |
192.168.0.0 |
192.168.255.255 |
IPv4 is short from Internet Protocol Version 4 is the fourth version of the Internet Protocol which are used to identify a single device a TCP/IP network through an addressing system. In IPv4 an address consists of 32 bits, which allows 2^32 addresses which are just over 4 billion addresses. IPv4 addresses consists of four decimal numbers, each ranging from 0 to 255, separated by dots for example 192.168.1.1.
IPv6 (Internet Protocol version 6) is a new and an upgrade version of IP version 4 (IPv4). Devices can use IPv6 as source and destination addresses to pass packets over a network. The most obvious improvement in IPv6 over IPv4 is that IP addresses are lengthened from 32 bits to 128 bits. Does not require manual configuration or DHCP . IPv6 also supports auto-configuration to help correct most of the shortcomings in version 4. Ip 6 Supports a 1280-byte packet size (without fragmentation).
Subnetting is the strategy used to partition a single physical network into more than one smaller logical sub-networks (subnets). Subnets were initially designed for solving the shortage of IP addresses over the Internet. Subnets are designed by accepting bits from the IP address's host part and using these bits to assign a number of smaller sub-networks inside the original network. Subnetting allows an organization to add sub-networks without the need to acquire a new network number via the Internet service provider (ISP). Subnetting helps to reduce the network traffic and conceals network complexity. Subnetting is essential when a single network number has to be allocated over numerous segments of a local area network (LAN). For Example if we have two partition in our network A- with ip 10.0.0.0/24 and B: with IP 10.1.0.0/24
In a wireless local area network (WLAN), an access point is a station that transmits and receives data (sometimes referred to as a transceiver). An access point connects users to other users within the network and also can serve as the point of interconnection between the WLAN and a fixed wire network. Each access point can serve multiple users within a defined network area as people move beyond the range of one access point, they are automatically handed over to the next one.
A routed protocol is a Network Layer protocol that is used to move traffic between networks. IP, IPX, and AppleTalk are all examples of routed protocols. Routed protocols are contains a network address as well as a device address. It allows packets to be forwarded from one network to another. For example TCP/IP, IPX, AppleTalk etc are the some of the routed protocols.
Ping command is an external command which is used to test the network connections. When we connect any device with other device then ping command verify that a device can communicate with another on a network. The ping command basically send request messages to the destination device and waiting for a response and then display that how many of those responses are returned, and how long it takes for them to return.
Syntax
ping [- option] destination
For example Ping yahoo.com
Where Options are:
-t Pings the specified host until stopped.
-a Resolve addresses to hostnames.
-n Count Number of echo requests to send.
-w Timeout in milliseconds to wait for each reply.
For Example:
Ping -t yahoo.com
Ipconfig command displays all current TCP/IP network configuration values. When we use simple ipconfig command without any parameters then its display the IP address, subnet mask, and default gateway for all adapters. We can also use Ipconfig command with different parameters which are:
/all : Displays the full TCP/IP configuration for all adapters.
/renew [Adapter] : Renews DHCP configuration for all adapters (if an adapter is not specified) or for a specific adapter if the Adapter parameter is included. This parameter is available only on computers with adapters that are configured to obtain an IP address automatically.
/release [Adapter] : Release the current DHCP configuration and discard the IP address configuration for either all adapters or for a specific adapter.
Syntax
ipconfig [/all] [/renew [Adapter]] [/release [Adapter]] [/flushdns] [/displaydns] [/registerdns] [/showclassid Adapter] [/setclassid Adapter [ClassID]]
Traceroute is a computer network diagnostic tool for displaying the route (path) and measuring transit delays of packets across an Internet Protocol (IP) network.
Traceroute is available almost in all operating systems. In Microsoft OS you can use tracert command.
When we apply Tracert command in MS windows then first of all it display the IP address of given domain, and what the maximum number of hops will be before it times out.
Next it gives information about each router it passes through on the way to its destination and then information of ISP the origin computer is connected.
For example:
C:\ tracert yahoo.com
Notes of Computer Network
Notes of MS Access
Notes of Adobe Photoshop For DIT
Notes of Inpage
Notes of Database
Notes of E-Commerce
Notes of Web Technology / HTML
Notes of Microsoft Word 2007
Notes of MS Excel 2007
Notes of C Language
Notes of Operating System For DIT
Notes of information technology Part -1
Notes of information technology Part -2
Notes of CorelDraw
Notes of Power Point