Introduction to computer networks
- 1. Pranab Bandhu Nath (Senior Lecturer) Department of CSE City University, Dhaka. Name : Maksudujjaman ID : 1915002517 Batch : 50 th Semester : Summer’21 Program : B.Sc. in CSE Submitted By : CITY UNIVERSITY Faculty of Science and Engineering Department of Computer Science & Engineering CSE 317 Computer Networks, Summer’21 Supervised By : This note is about the basic introduction of computer networks. It contain detailed description about computer network, ARPANET, goals of computer network, application of computer network and details about networking hardware & software components. Course Code: CSE 317 Course Title : Computer Networks ABSTACT:
- 2. Introduction To Computer Networks Introduction: A computer network is a group of computers that use a set of common communication over digital interconnections for the purpose of sharing resources located on or provided by the network nodes. The interconnections between nodes are formed form a broad spectrum of telecommunication network technologies, based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies. History: 18th Centuries: Watt’s Steam Engine Optical Telegraph The lightning rod 19th Centuries: Telegraph-1837, Telephone-1876 Electric Battery-1800, Camera-1888 Typewriter-1867 20th Centuries: Radio, Television The personal computer Information Gathering, Processing & Distribution 21th Centuries: Satellites, Fiber Optics, Internet ARPANET: ARPANET stands for “Advance Research Projects Agency Network”. Arpanet was the network that became basis for the internet. It a concept first published in 1967, ARPANET was developed under the direction of the U.S Advanced Research Projects Agency (ARPA).It is a project sponsored by U.S Department of Defense and planted in 1969 to connect computers at U.S Defense and different universities. ARPAET is sometimes referred to as DARPANET , Because ARPA’s name was changed to Defense Advanced Research Projects Agency (DARPA) in 1971. In 1980s, NSFnet was started to make high capacity network, which are more capable than ARPANET. In 1990s the internetworking of ARPANET, NSFnet and other private networks resulted into internet. What is Computer Network? A computer network is a group of two or more computers or other electronic devices that are interconnected for the purpose of exchanging data and sharing resources. It can transmit, receive and exchange data, voice and video traffic.
- 3. Goals of Computer Network: 1. Resourcesharing: Many organization has a substantial number of computers in operations, which are located apart. Ex. A group of office workers can share a common printer, fax, modem, scanner, etc. 2. Performance: It is measured in terms of transit time and response time. o Transit time is the time for a message to travel from one device to another o Response time is the elapsed time between an inquiry and a response. Performance dependent on the number of users, type of transmission medium, capability of connected network, efficiency of software. 3. High Reliability: If there are alternate sources of supply, all files could be replicated on two or more machines. If one of them is not available, due to hardware failure, the other copies could be used. 4. Security: It means protecting data from unauthorized access. 5. Scalability: Network must be scalable so that it is can be extended by adding new devices. Application of Computer Network: o Business o Communication Medium o E-commerce o Home Applications o Electronic commerce o Mobile users
- 4. Components of Computer Network: 1. Hardware: NIC, Server, Client, Transmission Media, Router, Bridge, Hub, Switch, Gateway, Repeaters. 2. Software: Network Operating System, Protocols Switches, Client Software. 3. Cables & Connectors: Twisted pair cable, Coaxial cable, Fiber-optic cable. Hardware Components: NIC (Network Interface Card): It is a hardware device that connects a computer to a network both functionally and physically. The main purpose of NIC is to format data, send and receive data at receiver node. Servers: Servers are high-configuration computers that manage the resources of the network. The network operating system is typically installed in the server and so they give user accesses to the network resources. Servers can be of various kinds: file servers, database servers, print servers etc. Client: Clients are computers that request and receive service from the servers to access and use the network resources. Peers: Peers are computers that provide as well as receive services from other peers in a workgroup network. Transmission Media: Transmission media are the channels through which data is transferred from one device to another in a network. Transmission media may be guided media like coaxial cable, fibre optic cables etc; or maybe unguided media like microwaves, infra-red waves etc. Connecting Devices: Connecting devices act as middleware between networks or computers, by binding the network media together. Some of the common connecting devices are: o Router o Bridge o Hub o Repeater o Gateway o Switche Software Components: Networking Operating System: Network Operating Systems is typically installed in the server and facilitate workstations in a network to share files, database, applications, printers etc. Protocol Switches: A protocol is a rule or guideline followed by each computer for data communication. Protocol switches is a set of related protocols that are laid down for computer networks. The two popular protocol switches are- OSI Model (Open System Interconnection) and TCP / IP Model.