Introduction-to-Computer-Networks (1).pptx

Introduction-to-Computer-Networks (1).pptx

• 1.
  Introduction to Computer Networks Networksconnect computers to share information and resources. This presentation explores the fundamentals of computer networking, from historical development to modern applications, protocols, and architecture models.
• 2.
  Network Definition &Historical Development What is a Network? "A group of computers & other devices such as printers, workstations, and servers that are linked together to share information and resources." Networking refers to the concepts of connected computers and devices sharing information, resources, or both. Historical Development In the mid-1960s, mainframe computers were standalone devices. The Advanced Research Projects Agency (ARPA) developed ARPANET in 1967 to connect research computers. By 1969, ARPANET connected four nodes (UCLA, UCSB, SRI, University of Utah) using Interface Message Processors (IMPs) and Network Control Protocol (NCP).
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  Uses of ComputerNetworks Resource Sharing • File sharing between network users • Hardware sharing (printers, drives) • Program sharing (applications) • Internet connection sharing Communication • Electronic mail • Newsgroups • Video conferencing • Person-to-person communication Data Management • Centralized data storage • User access control • Data security • Information sharing Entertainment & Home Use • Internet access • Interactive entertainment • Electronic commerce • Access to remote information
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  Network Design Criteria Performance Measuredby transit time (message travel time) and response time (time between inquiry and response). Also affected by software efficiency, number of users, and hardware capability. Reliability Determines frequency of network failures. More failures mean less reliability. Critical for business operations and data integrity. Scalability Network's ability to grow and accommodate new users and technologies without performance degradation. Essential for evolving organizations. Security Protection of data from unauthorized access. Includes authentication, encryption, and access controls to prevent eavesdropping and data alteration. Routing Selecting optimal paths for data transmission based on cost and time. Various algorithms determine the most efficient routes. Flow Control Prevents receiver overflow when sender produces data faster than receiver can process it. Ensures smooth data transmission.
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  Data Transmission &Service Types Data Transmission Modes Connection-Oriented vs. Connectionless Services Connection-Oriented • Establishes connection before data transfer • Follows sequence: connect, send, release • More reliable with error checking • Example: TCP protocol Connectionless • No connection establishment required • Similar to postal service • No delivery guarantee • Example: UDP protocol Service Primitives: LISTEN, CONNECT, RECEIVE, SEND, and DISCONNECT operations enable communication between layers.
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  Protocol Hierarchies Networks uselayered protocols where each layer offers services to higher layers while hiding implementation details. This concept is similar to information hiding and object-oriented programming. A protocol is an agreement between communicating parties on how communication proceeds. Processes in corresponding layers on different machines are called peers. Key Concepts • Virtual communication occurs between peer layers • Physical communication happens only at the lowest layer • Each layer adds headers to messages as they pass down • Headers contain control information for peer layers • A set of layers and protocols is called a Network Architecture • A list of protocols used by a system is called a protocol stack
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  OSI Reference Model TheOpen Systems Interconnection (OSI) model, released by ISO in 1984, is a seven-layer framework that standardizes network communication processes. Application (7) User interface, file transfer, email (FTP, HTTP, SMTP) Presentation (6) Data formatting, encryption, compression (ASCII, JPEG, MPEG) Session (5) Dialog control, synchronization Transport (4) End-to-end connections, reliability (TCP, UDP) Network (3) Routing, addressing, packet forwarding (IP) Data Link (2) Media access, error detection (Ethernet, WiFi) Physical (1) Bits transmission, cables, signals
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  TCP/IP Model TCP/IP (TransmissionControl Protocol/Internet Protocol) was developed by the Department of Defense's Project Research Agency (ARPA) and is the foundation of the modern Internet. 1 Application Layer Provides network services to applications. Includes protocols like TELNET, FTP, SMTP, and DNS for various communication functions. 2 Transport Layer Handles data transmission paths, multiplexing, and segmentation. Ensures proper sequencing of packets and adds header information. 3 Internet Layer Enables packet routing across networks. Uses IP to deliver packets independently to their destination, regardless of order. 4 Host-to-Network Layer Lowest layer that connects hosts to the network. Varies between different network types and hardware configurations. Advantages of TCP/IP • Operates independently • Highly scalable • Client/server architecture • Supports multiple routing protocols • Enables computer-to-computer connections Limitations • Transport layer doesn't guarantee packet delivery • Limited to specific applications • Difficult protocol replacement • Services, interfaces, and protocols not clearly separated