💻Information Systems Unit 4 – Data Communication and Networking

Key Concepts and Terminology

• Data communication involves the exchange of data between two devices via some form of transmission medium (copper wire, optical fiber, wireless)
• A computer network consists of a collection of computing devices that can communicate with each other and share resources
  • Resources can include files, printers, applications, and services
• Bandwidth measures the amount of data that can be transmitted over a communication channel per unit of time (bps, Kbps, Mbps, Gbps)
• Latency refers to the delay between the time data is sent from the source and the time it is received at the destination
• Throughput represents the actual amount of data that is successfully transmitted over a communication channel per unit of time
• Network topology describes the physical or logical layout of a network (bus, star, ring, mesh)
• Protocol defines a set of rules, formats, and procedures for communication between devices in a network (TCP/IP, HTTP, FTP)

Network Models and Architectures

• The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the communication functions of a computing system into seven abstraction layers
  • Layers include physical, data link, network, transport, session, presentation, and application
  • Each layer performs specific functions and communicates with the layers above and below it
• The TCP/IP model is a simplified version of the OSI model and consists of four layers (link, internet, transport, application)
• Client-server architecture is a distributed computing model where clients request services from a central server
  • Examples include web browsers (clients) accessing web pages from a web server
• Peer-to-peer (P2P) architecture allows each node in the network to act as both a client and a server, sharing resources directly with other nodes
  • Used in file-sharing applications (BitTorrent) and blockchain networks (Bitcoin)
• Three-tier architecture separates the presentation, application processing, and data management functions into separate tiers
  • Commonly used in web applications with a web browser (presentation tier), application server (application tier), and database (data tier)

Data Transmission Basics

• Data transmission can occur in three modes: simplex (one-way communication), half-duplex (two-way, but not simultaneous), and full-duplex (two-way, simultaneous)
• Analog transmission represents data using continuous signals that vary in amplitude, frequency, or phase
  • Examples include voice signals over telephone lines and radio waves
• Digital transmission represents data using discrete signals with a limited number of defined values (binary: 0 and 1)
  • Used in computer networks, as digital data is more reliable and easier to process than analog data
• Synchronous transmission sends data in a continuous stream, with the sender and receiver synchronized using a clock signal
  • Efficient for large amounts of data, but requires a dedicated communication channel
• Asynchronous transmission sends data in small packets, with start and stop bits to indicate the beginning and end of each packet
  • More flexible and cost-effective than synchronous transmission, as it does not require a dedicated channel
• Multiplexing techniques (TDM, FDM, WDM) allow multiple signals to share the same communication channel by dividing it into separate time slots, frequency bands, or wavelengths

Network Protocols and Standards

• IP (Internet Protocol) is responsible for addressing and routing data packets across the internet
  • IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses to support more devices
• TCP (Transmission Control Protocol) provides reliable, connection-oriented data delivery between applications
  • Establishes a virtual connection, ensures data integrity, and manages flow control
• UDP (User Datagram Protocol) offers a connectionless, unreliable data delivery service
  • Used for real-time applications (VoIP, video streaming) where speed is more important than reliability
• HTTP (Hypertext Transfer Protocol) is the foundation of data exchange on the World Wide Web
  • Defines how web browsers request resources from web servers and how servers respond
• FTP (File Transfer Protocol) enables the transfer of files between computers over a network
• SMTP (Simple Mail Transfer Protocol) is used for sending and receiving email messages
• Wi-Fi standards (802.11a/b/g/n/ac/ax) define the protocols and specifications for wireless local area networks (WLANs)

Network Hardware and Infrastructure

• Network interface cards (NICs) connect a computer to a network and have a unique MAC (Media Access Control) address for identification
• Switches operate at the data link layer and forward data packets between devices within a network based on MAC addresses
  • Managed switches offer advanced features like VLANs, QoS, and port mirroring
• Routers operate at the network layer and forward data packets between different networks based on IP addresses
  • Use routing tables and protocols (RIP, OSPF, BGP) to determine the best path for data transmission
• Firewalls monitor and control incoming and outgoing network traffic based on predetermined security rules
  • Can be hardware-based (standalone appliance) or software-based (running on a server or computer)
• Modems (modulator-demodulator) convert digital signals from a computer into analog signals for transmission over telephone lines, and vice versa
• Wireless access points (WAPs) allow wireless devices to connect to a wired network using Wi-Fi
• Cables used in networks include coaxial cable, twisted pair (UTP/STP), and fiber optic cable
  • Choice depends on factors like bandwidth, distance, cost, and environment

Wireless and Mobile Networks

• Wireless networks use radio waves, microwaves, or infrared signals to transmit data without physical connections
  • Enable mobility, flexibility, and easier installation compared to wired networks
• Cellular networks (2G, 3G, 4G, 5G) provide wide-area wireless communication for mobile devices
  • Use a network of base stations and cell towers to cover large geographic areas
• Bluetooth is a short-range wireless technology for connecting devices (headphones, keyboards, smartwatches) within close proximity
• NFC (Near Field Communication) allows smartphones and other devices to establish radio communication by bringing them close together or touching them
  • Used for contactless payments, access control, and data exchange
• Satellite communication uses orbiting satellites to relay data signals between Earth-based stations
  • Enables global coverage and communication in remote areas, but has higher latency and cost compared to terrestrial networks
• IoT (Internet of Things) refers to the growing network of connected devices (sensors, appliances, vehicles) that can collect and exchange data
  • Enables applications like smart homes, industrial automation, and remote monitoring

Network Security and Encryption

• Network security aims to protect the confidentiality, integrity, and availability of data and resources in a network
• Encryption is the process of converting plaintext into ciphertext using an encryption algorithm and a secret key
  • Prevents unauthorized access to sensitive data during transmission or storage
• Symmetric encryption uses the same key for both encryption and decryption (AES, DES)
  • Faster and more efficient than asymmetric encryption, but requires secure key exchange
• Asymmetric encryption (public-key cryptography) uses a pair of keys: a public key for encryption and a private key for decryption (RSA, ECC)
  • Eliminates the need for secure key exchange, but is slower than symmetric encryption
• Digital signatures use asymmetric encryption to verify the authenticity and integrity of a message or document
• VPN (Virtual Private Network) creates a secure, encrypted tunnel between a remote user and a private network over the internet
  • Allows secure access to corporate resources and protects data from interception
• Firewall rules and access control lists (ACLs) enforce network security policies by allowing or blocking specific traffic based on criteria like IP addresses, ports, and protocols
• Intrusion detection systems (IDS) and intrusion prevention systems (IPS) monitor network traffic for suspicious activities and potential security threats

Emerging Trends in Networking

• Software-defined networking (SDN) separates the network control plane from the data plane, enabling centralized, programmable network management
  • Offers greater flexibility, scalability, and automation compared to traditional network architectures
• Network function virtualization (NFV) decouples network functions (routing, firewalling, load balancing) from proprietary hardware and runs them as software on virtualized infrastructure
  • Reduces costs, improves agility, and enables faster deployment of new services
• Edge computing brings computation and data storage closer to the sources of data (IoT devices, sensors) to reduce latency and bandwidth requirements
  • Enables real-time processing and decision-making for applications like autonomous vehicles and industrial automation
• 5G networks promise higher speeds, lower latency, and massive device connectivity compared to previous generations of cellular networks
  • Will enable new use cases like virtual reality, remote surgery, and smart cities
• Wi-Fi 6 (802.11ax) improves upon previous Wi-Fi standards by offering higher throughput, better performance in dense environments, and increased energy efficiency
• Quantum computing has the potential to revolutionize cryptography and network security by breaking current encryption algorithms
  • Research is ongoing to develop quantum-resistant cryptographic methods (post-quantum cryptography)
• Blockchain technology can be used to create decentralized, secure, and transparent networks for applications like supply chain management, identity verification, and secure data sharing