CN_Introduction Concepts.pdf

(Computer Network: Module 1) Topic: Introduction Concepts By: Chhavi Bajpai Assistant Professor Computer Engineering & Applications GLA University, Mathura What is a Computer Network? A computer network is a telecommun...

(Computer Network: Module 1) Topic: Introduction Concepts By: Chhavi Bajpai Assistant Professor Computer Engineering & Applications GLA University, Mathura What is a Computer Network? A computer network is a telecommunications network, which allows digital devices (nodes) to exchange data between each other using either wired or wireless connections to share resources (hardware or software) e.g. internet. A collection of autonomous computers interconnected by a single technology. Another definition: “A network is a set of devices (often referred to as nodes) connected by communication links.” A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. A link can be a cable, air, optical fiber, or any medium which can transport a signal carrying information. Data Communication Data Communications are exchange of data between two devices via some transmission medium. It has five components: 1. Message- information(data) to be communicated e.g. text, audio, video etc. 2. Sender- device how sends the message (computer, phone, television etc) 3. Receiver- device how receives the message (computer, phone, television) 4. Transmission medium- is the physical path by which a message travels from sender to receiver. 5. Protocol- the set of rules that governs the data communication. Goals of Computer Network To provide sharing of resources such as information, devices or processors To provide inter-process communication among user and processors. It provides the network user with maximum performance at minimum cost It provides centralized control for a geographically distributed system. It provides compatibility of dissimilar equipment and software. It provides centralized management and allocation of network resources. It provides distributed processing functions. Application of Computer Network 1. Communication: Email and Instant Messaging: Networks facilitate email services and real-time messaging applications, allowing people to communicate efficiently across the globe. VoIP (Voice over Internet Protocol): Services like Skype, Zoom, and WhatsApp use network protocols to provide voice and video calls over the internet. 2. Data Sharing and Collaboration: File Sharing: Networks enable the transfer and sharing of files between users or systems, whether through cloud storage services like Google Drive or traditional file transfer protocols. Collaborative Tools: Platforms like Microsoft Teams and Google Workspace allow multiple users to work on documents, spreadsheets, and presentations simultaneously. 3. Internet Access: Web Browsing: Networks connect users to the World Wide Web, providing access to information, services, and resources online. Streaming Services: Services like Netflix, Hulu, and Spotify use networks to deliver video and audio content on demand. 4. Remote Access: Remote Desktop: Network protocols allow users to access and control their desktop computers from remote locations, which is crucial for remote work. Virtual Private Networks (VPNs): VPNs provide secure access to a private network over the internet, often used for secure remote work and accessing restricted resources. 5. Business Operations: Enterprise Networks: Companies use internal networks to support operations, manage resources, and enable communication between departments. Customer Relationship Management (CRM) Systems: Networks facilitate the integration and management of customer data, improving service and interaction. 6. E-Commerce: Online Shopping: Networks enable online transactions, allowing users to browse, purchase, and pay for goods and services over the internet. Payment Gateways: Secure network connections process payments and transactions, ensuring the safety and reliability of online financial exchanges. 7. Entertainment and Gaming: Online Gaming: Networks support multiplayer online games, allowing players to connect, compete, and collaborate across distances. Social Media: Platforms like Facebook, Twitter, and Instagram rely on networks to connect users and facilitate social interactions and content sharing. 8. Education and Training: E-Learning: Networks support online courses, virtual classrooms, and educational resources, enabling remote learning and access to knowledge. Training Simulations: Networks facilitate simulations and interactive training programs for various fields, from healthcare to aviation. 9. Healthcare: Telemedicine: Networks enable remote consultations between patients and healthcare providers, improving access to medical care. Electronic Health Records (EHRs): Secure network systems manage and share patient records across healthcare facilities. 10. Smart Technologies: IoT (Internet of Things): Networks connect smart devices and sensors, enabling automation and data collection in homes, cities, and industries. Smart Cities: Networks support smart infrastructure, including traffic management, utilities, and public services. 11. Research and Development: Distributed Computing: Networks enable collaborative research and computational tasks across multiple systems, often used in scientific research and large-scale simulations. TYPES OF COMMUNICATION TYPES OF COMMUNICATION/ TRANSMISSION Simplex Mode In Simplex mode, the communication is unidirectional, as on a one-way street. Only one of the two devices on a link can transmit, the other can only receive. The simplex mode can use the entire capacity of the channel to send data in one direction. The radio station is a simplex channel as it transmits the signal to the listeners but never allows them to transmit back. Example: Keyboard and traditional monitors. The keyboard can only introduce input, the monitor can only give the output. Half-Duplex mode In a Half-duplex channel, direction can be reversed, i.e., the station can transmit and receive the data as well. Messages flow in both the directions, but not at the same time. The entire bandwidth of the communication channel is utilized in one direction at a time. In half-duplex mode, it is possible to perform the error detection, and if any error occurs, then the receiver requests the sender to retransmit the data. A Walkie-talkie is an example of the Half-duplex mode. In Walkie-talkie, one party speaks, and another party listens. After a pause, the other speaks and first party listens. Speaking simultaneously will create the distorted sound which cannot be understood. Full-duplex mode In Full duplex mode, the communication is bi-directional, i.e., the data flow in both the directions. Both the stations can send and receive the message simultaneously. Full-duplex mode has two simplex channels. One channel has traffic moving in one direction, and another channel has traffic flowing in the opposite direction. The Full-duplex mode is the fastest mode of communication between devices. The most common example of the full-duplex mode is a telephone network. When two people are communicating with each other by a telephone line, both can talk and listen at the same time.  Types of connection 1. Point to point A point-to-point connection provides a dedicated link between two devices. The entire capacity of the link is reserved for transmission between those two devices. Most point-to-point connections use an actual length of wire or cable to connect the two ends, but other options, such as microwave or satellite links, are also possible which are shown in the following figure. 2.Multipoint: A multipoint (also called multidrop) connection is one in which more than two specific devices share a single link as shown in the following figure.  Types of Computer Networks (Based on network span or geographical spread) 1. Personal Area Network (PAN) PAN is the most basic type of computer network. It is a type of network designed to connect devices within a short range, typically around one person. It allows your personal devices, like smartphones, tablets, laptops, and wearables, to communicate and share data with each other. PAN offers a network range of 1 to 100 meters from person to device providing communication. Its transmission speed is very high with very easy maintenance and very low cost. This uses Bluetooth, IrDA, and Zigbee as technology. Examples of PAN are USB, computer, phone, tablet, printer, PDA, etc.  2. Local Area Network (LAN) LAN is the most frequently used network. A LAN is a computer network that connects computers through a common communication path, contained within a limited area, that is, locally. A LAN encompasses two or more computers connected over a server. The two important technologies involved in this network are Ethernet and Wi-fi. It ranges up to 2km & transmission speed is very high with easy maintenance and low cost. Examples of LAN are networking in a home, school, library, laboratory, college, office, etc.  3. Campus Area Network (CAN) CAN is bigger than a LAN but smaller than a MAN. This is a type of computer network that is usually used in places like a school or colleges. This network covers a limited geographical area that is, it spreads across several buildings within the campus. CAN mainly use Ethernet technology with a range from 1km to 5km. Its transmission speed is very high with a moderate maintenance cost and moderate cost. Examples of CAN are networks that cover schools, colleges, buildings, etc. 4. Metropolitan Area Network (MAN) A MAN is larger than a LAN but smaller than a WAN. This is the type of computer network that connects computers over a geographical distance through a shared communication path over a city, town, or metropolitan area. This network mainly uses FDDI, CDDI, and ATM as the technology with a range from 5km to 50km. Its transmission speed is average. It is difficult to maintain and it comes with a high cost. Examples of MAN are networking in towns, cities, a single large city, a large area within multiple buildings, etc. MAN (Continued) 5. Wide Area Network (WAN) WAN is a type of computer network that connects computers over a large geographical distance through a shared communication path. It is not restrained to a single location but extends over many locations. WAN can also be defined as a group of local area networks that communicate with each other with a range above 50km. Here we use Leased-Line & Dial-up technology. Its transmission speed is very low and it comes with very high maintenance and very high cost. The most common example of WAN is the Internet. WAN (Continued) Comparison of Different Computer Networks Parameters PAN LAN CAN MAN WAN Personal Area Local Area Campus Area Metropolitan Area Full Name Network Network Network Network Wide Area Network Bluetooth, Leased Line, Dial- Technology IrDA,Zigbee Ethernet & Wifi Ethernet FDDI, CDDI, ATM Up Range 1-100 m Upto 2km 1 – 5 km 5-50 km Above 50 km Transmission Very High Very High High Average Low Speed Ownership Private Private Private Private or Public Private or Public Maintenance Very Easy Easy Moderate Difficult Very Difficult Cost Very Low Low Moderate High Very High  Types of Computer Networks (Based on Design and Implementation) 1) Client-Server Network 2) Peer to Peer Network  In a client–server network, there is at least one dedicated central server that controls the network, and a number of clients connect to the server to carry out specific tasks. A client-server network can have more than one central server, each performing a specific function. Functions may include user access, data storage, internet connection management, and network traffic monitoring, among others. Multiple clients connect to one central server. A client is a computer or computer-controlled device that provides users with access to data on the remote server. Types of clients include smartphones, desktop computers, and laptops. This network architecture facilitates efficient communication and resource sharing between the central server and connected clients, enabling seamless task execution and data access across various devices.  In a peer-to-peer network, there is no central server controlling the network. Instead, all the computers in the network are connected to one another and share resources such as files, applications, and programs. In a peer-to-peer network, each computer can function as either a client or a server, enabling it to request or provide services. Each computer is referred to as a peer and possesses the same capabilities and access rights. No peer has control over another. For example, a printer connected to one computer can be utilized by any other computer on the network. Similarly, one computer in the network can access or delete data from other computers. Since resource management and network security are not controlled centrally, it is essential to have local backups for each computer. Peers can communicate directly with each other, and there are no restrictions when adding a device to a peer- to-peer network.  Types of Computer Networks (Based on Communication Channel) 1. Wired Computer Networks: Definition: Wired computer networks use physical cables to connect devices and transmit data. These networks are known for their stability, reliability, and high speeds, as the physical connections help minimize interference and signal degradation. Typical Use Cases: Ideal for environments requiring consistent and high-speed connections, such as in offices, data centers, and large buildings. 2. Wireless Computer Networks: Definition: Wireless computer networks use radio waves or infrared signals to connect devices without physical cables. They offer greater flexibility and mobility, allowing devices to connect from various locations within the network’s coverage area. Typical Use Cases: Suitable for mobile and flexible environments like homes, public spaces, and on-the-go applications where cabling is impractical.