Computer networks
- 1. Computer Networks CLASS NOTE-1 Lecturer Pranab Bandhu Nath Senior Lecturer CSE Department City University, Dhaka STUDENT NAME :MD HASNAIN ID :1834902583 Department of CSE City University, Dhaka.
- 2. Lesson Title Introduction to Computer Networks: Basic concept of Computer networks Goals of networking Arpanet: ARPANET was the network that became the basis for the Internet. Based on a concept first published in 1967, ARPANET was developed under the direction of the U.S. Advanced Research Projects Agency (ARPA). In 1969, the idea became a modest reality with the interconnection of four university computers. The initial purpose was to communicate with and share computer resources among mainly scientific users at the connected institutions. ARPANET took advantage of the new idea of sending information in small units called packets that could be routed on different paths and reconstructed at their destination. The development of the TCP/IP protocols in the 1970s made it possible to expand the size of the network, which now had become a network of networks, in an orderly way. • Advanced Research Projects Agency Network (ARPANET) • U.S. Defense Department, funded the development of the Advanced Research Projects Agency Network (ARPANET) in the late 1960s. Its initial purpose was to link computers at Pentagon-funded research institutions over telephone lines. • At the height of the Cold War, military commanders were seeking a computer communications system without a central core, with no headquarters or base of operations that could be attacked and
- 3. destroyed by enemies thus blacking out the entire network in one fell swoop. • Defense Department put out a call for competitive bids to build the network, and in January 1969 Bolt, Beranek, and Newman (BBN) of Cambridge, Massachusetts, won the $1 million contract. What is Computer Network? • A computer network is a set of computers connected together for the purpose of sharing resources. The most common resource shared today is connection to the Internet. Other shared resources can include a printer or a file server. The Internet itself can be considered a computer network. Goals of Computer Network • Sharing Resources from one Computer to another Computer over a network . • Performance by measuring the speed of data transmission with number of users, connectivity and the software used . • Reliability makes easy to use an alternative source for data communication in case of hardware failure or connectivity issues. • Scalability increases the system performance by adding more processors .
- 4. • Security is the main characteristics of Computer network where you can take necessary steps for protecting your data from unauthorized access. Application of Computer Network Computer network applications are network software applications that utilize the Internet or other network hardware infrastructure to perform useful functions for example file transfers within a network. They help us to transfer data from one point to another within the network. • Business Applications : A business application is a collection of components that provides a business functionality that you can use internally, externally, or with other business applications. You can create business applications of individual components, which are related to each other. • Communication Medium : Communication media refers to the means of delivering and receiving data or information. In telecommunication, these means are transmission and storage tools or channels for data storage and transmission. • e-commerce : Electronic commerce or e-commerce is a business model that lets firms and individuals buy and sell things over the internet. E-commerce operates in all four of the following major market segments:
- 5. Business to business Business to consumer Consumer to consumer Consumer to business • Home Applications :The Home Application is where you can choose the first screen you want to see when you log into your Keep & Share account. • Electronic commerce : Electronic commerce or e-commerce is a business model that lets firms and individuals buy and sell things over the internet. E-commerce operates in all four of the following major market segments: Business to business Business to consumer Consumer to consumer Consumer to business • Mobile Users : Mobile-user meaning A smartphone or tablet user. Network Hardware & Software There are three component of Computer Network 1. Hardware Equipment 2. Software 3. Cables and Connectors
- 6. Hardware: NIC: A network interface controller is a computer hardware component that connects a computer to a computer network. Server: Servers are computers designed to wait for any requests from users or other computers and then act on that request. Their main purpose is to be there for you, to share data and perform tasks to keep your workflow smooth and productivity elevated. Client: In computing, a client is a piece of computer hardware or software that accesses a service made available by a server as part of the client–server model of computer networks. The server is often (but not always) on another computer system, in which case the client accesses the service by way of a network. Peers: In networking, a peer is a node that provides the same functionality as another. For example, two desktop PCs in a network are peers. A desktop PC and a server are not peers as they perform different operations. Transmission: Transmission line hardware is also called transmission line fitting or transmission line accessory. Transmission line hardware is a general called for all the fittings that used to connect the transmission line. They can survive in the heavy saline conditions along the coast. Medium: Medium is an open platform where readers find dynamic thinking, and where expert and undiscovered voices can share their writing on any topic. Router: The router is a physical or virtual internetworking device that is designed to receive, analyze, and forward data packets between computer networks.
- 7. Bridge: A network bridge is a computer networking device that creates a single, aggregate network from multiple communication networks or network segments. This function is called network bridging. Hub: When referring to a network, a hub is the most basic networking device that connects multiple computers or other network devices together. Switches: A switch is a device in a computer network that connects other devices together. Multiple data cables are plugged into a switch to enable communication between different networked devices. Gateway: A gateway is a piece of networking hardware or software used in telecommunications for telecommunications networks that allows data to flow from one discrete network to another. Gateways are distinct from routers or switches in that they communicate using more than one protocol to connect a bunch of networks and can operate at any of the seven layers of the open systems interconnection model. Repeaters: In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Software: Network Operating System: Network Operating System is a computer operating system that facilitates to connect and communicate various autonomous computers over a network. An Autonomous computer is an independent computer that has its own local memory, hardware,
- 8. and O.S. It is self capable to perform operations and processing for a single user. They can either run the same or different O.S. Network Protocol (TCP/IP, OSI): A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network. Essentially, it allows connected devices to communicate with each other, regardless of any differences in their internal processes, structure or design. Network protocols are the reason you can easily communicate with people all over the world, and thus play a critical role in modern digital communications. Cables and Connectors: Twisted pair cable: Twisted pair cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted balanced pair, a twisted pair reduces electromagnetic radiation from the pair and crosstalk between neighboring pairs and improves rejection of external electromagnetic interference. Coaxial cable : Coaxial cable, or coax is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric many coaxial cables also have a protective outer sheath or jacket. The term "coaxial" refers to the inner conductor and the outer shield sharing a geometric axis. Fiber-optic cable: A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable, but containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with plastic layers and
- 9. contained in a protective tube suitable for the environment where the cable is used. Different types of cable are used for different applications.