03 Introduction+To+Computer+Networks.pptx
- 1. Introduction To Computer Networks
- 2. Computer Networks A set of devices often mentioned as nodes connected by media link is called a Network. A node can be a device which is capable of sending or receiving data generated by other nodes on the network like a computer, printer etc. These links connecting the devices are called Communication channels. Computer network is a telecommunication channel using which we can share data with other computers or devices, connected to the same network. It is also called Data Network. The best example of computer network is Internet.
- 3. A network must be able to meet certain criteria's, these are mentioned below: Performance Reliability Scalability Performance It can be measured in the following ways: Transit time : It is the time taken to travel a message from one device to another. Response time : It is defined as the time elapsed between enquiry and response. Other ways to measure performance are : Efficiency of software Number of users Capability of connected hardware Computer Networks: Reliability It decides the frequency at which network failure take place. More the failures are, less is the network's reliability. Computer Networks: Security It refers to the protection of data from any unauthorised user or access. While travelling through network, data passes many layers of network, and data can be traced if attempted. Hence security is also a very important characteristic for Networks.
- 4. Basic Communication Model A Communication model is used to exchange data between two parties. For example: communication between a computer, server and telephone (through modem). Basic Communication Model Source Data to be transmitted is generated by this device, example: telephones, personal computers etc. Transmitter The data generated by the source system is not directly transmitted in the form its generated. The transmitter transforms and encodes the data in such a form to produce electromagnetic waves or signals.
- 5. Basic Communication Model Transmission System A transmission system can be a single transmission line or a complex network connecting source and destination. Receiver Receiver accepts the signal from the transmission system and converts it into a form which is easily managed by the destination device. Destination Destination receives the incoming data from the receiver.
- 6. Components of Data Communication Message: It is the information to be delivered. Sender: Sender is the person who is sending the message. Receiver: Receiver is the person to whom the message is being sent to. Medium: It is the medium through which the message is sent. For example: A Modem. Protocol: These are some set of rules which govern data communication.
- 7. Uses of Computer Networks Business Applications Following are some business applications of computer networks: Resource Sharing: The goal is to make all programs, equipments(like printers etc), and especially data, available to anyone on the network without regard to the physical location of the resource and the user. Server-Client model: One can imagine a company's information system as consisting of one or more databases and some employees who need to access it remotely. In this model, the data is stored on powerful computers called Servers. Often these are centrally housed and maintained by a system administrator. In contrast, the employees have simple machines, called Clients, on their desks, using which they
- 8. Uses of Computer Networks Communication Medium: A computer network can provide a powerful communication medium among employees. Virtually every company that has two or more computers now has e-mail (electronic mail), which employees generally use for a great deal of daily communication eCommerce: A goal that is starting to become more important in businesses is doing business with consumers over the Internet. Airlines, bookstores and music vendors have discovered that many customers like the convenience of shopping from home. This sector is expected to grow quickly in the future.
- 9. Computer Networks: Home Applications Some of the most important uses of the Internet for home users are as follows: Access to remote information Person-to-person communication Interactive entertainment Electronic commerce
- 10. Computer Networks: Mobile Users Mobile computers, such as notebook computers and Mobile phones, is one of the fastest-growing segment of the entire computer industry. Although wireless networking and mobile computing are often related, they are not identical.
- 11. Line Configuration in Computer Networks A Network is nothing but a connection made through connection links between two or more devices. Devices can be a computer, printer or any other device that is capable to send and receive data. There are two ways to connect the devices : Point-to-Point connection Multipoint connection Point-To-Point Connectiont It is a protocol which is used as a communication link between two devices. It is simple to establish. The most common example for Point-to-Point connection (PPP) is a computer connected by telephone line.
- 12. MultiPoint Connection It is also called Multidrop configuration. In this connection two or more devices share a single link. There are two kinds of Multipoint Connections : If the links are used simultaneously between many devices, then it is spatially shared line configuration. If user takes turns while using the link, then it is time shared (temporal) line configuration.