Computer Networks Lecture #2

Lecture #2: Computer Networks

• Lecture presented by Dr. Abdelaziz Mohamed
• Covers computer networks, applications, characteristics, media, protocols, and hardware.

Overview

• Defines computer networks and common communications applications.
• Includes networking concepts and terminology.
• Discusses technical issues, data transmission characteristics, and transmission media types.
• Explains communication protocols and networking standards.
• Explores various hardware types used in computer networks.

What is a Network?

• A network is a connected system of objects or people.
• A computer network is a collection of computers and other devices connected to share hardware, software, data, and communicate electronically.
• Computer networks are merging with telephone and other communication systems.
• Networks range from small private networks to the Internet.
• Computer networks are essential in most businesses.

Networking Applications

• Cellular (cell) Phones: Functionality depends on being within range of a cell tower; dual-mode phones can seamlessly switch between Wi-Fi and cellular networks.
• Dual-mode Phones: Enable users to make calls using multiple communication networks.
• Satellite Phones: Use satellite technology, commonly used by soldiers, journalists, wilderness guides, and researchers.
• Television and Radio Broadcasting: Deliver TV and radio content to the public using cable, satellite, and private closed-circuit TV networks.
• Global Positioning System (GPS) Applications: Use satellites and receivers to determine geographic location (GPS receivers).
• Monitoring Systems: Use networking technology to monitor the status or location of objects; RFID- and GPS-based systems monitor location, with examples including vehicle and child monitoring systems and home healthcare monitors.
• Multimedia Networking: Distributing digital multimedia content typically through a home network. Networking capabilities are built into devices like digital media receivers and streamers, allowing content to be viewed at a more convenient location; examples include Slingbox. Sensor networks are also used in applications such as home automation.
• Videoconferencing, Collaborative Computing, and Telecommuting: Use computers, video cameras, microphones, and networking technologies to conduct face-to-face meetings; telepresence videoconferencing systems more closely mimic real-time meetings.
• Telemedicine: Uses networking technology to provide medical information and services, including remote monitoring, consultations, and diagnosis.
• Telesurgery: Robot-assisted surgery where the doctor's location is different from the patient and robot; necessary for long-term space exploration.

Network Characteristics

• Wired vs. Wireless Networks: Wired networks use cables to connect devices (schools, businesses, government); wireless networks use radio waves (homes, schools, businesses).
• Network Topologies: Indicate how devices are arranged; Star Networks connect all networked devices through a central device/server; if the central device fails, the network fails.
• Bus Networks rely on a central cable to connect all network devices.
• Mesh Networks employ multiple connections among devices, enabling messages to follow various paths.
• Peer-to-Peer (P2P) Networks: Do not use a central server; all computers on the network function at the same level; users have direct access to all devices on the network; less complicated and less expensive to implement than client-server networks; internet P2P computing involves content exchange directly between users.
• Network Size and Coverage Area: Personal Area Networks (PANs) connect personal devices located close together; Local Area Networks (LANs) connect devices in a small geographic area; Metropolitan Area Networks (MANs) cover metropolitan areas; Wide Area Networks (WANs) cover a large geographic area.
• Intranets and Extranets: Intranet is a private network for employees; similar to the Internet; Extranet is a company's network accessible by authorized outsiders.
• Virtual Private Networks (VPNs): Secure paths over the Internet that provide authorized access to a private network.
• Data Transmission Characteristics:
  • Simplex: Data travels in one direction only.
  • Half-Duplex: Data can travel in either direction, but only one way at a time.
  • Full-Duplex: Data travels in both directions simultaneously.
  • Delivery Methods:
    • Circuit-Switching: Uses a dedicated circuit for communication.
    • Packet-Switching: Sends data as individual packets for transmission and reassembly.
    • Broadcasting: Sends data to all nodes within range; the recipient retrieves the data.
  • Serial: Data is sent one bit at a time.
  • Parallel: Data is sent as a byte with each bit along a different path.
  • Synchronous: Data is transferred at regular intervals.
  • Asynchronous: Data is sent when ready, with start and stop bits.
  • Isochronous: Data is sent at the same time as other data.

Summary

• Covers networking applications, network characteristics, data transmission characteristics, networking media, communications protocols, and networking standards.

Join Dr. Abdelaziz Mohamed in Lecture #2 as he delves into the world of computer networks. This session covers key concepts such as applications, media, protocols, and hardware essential for understanding networking systems. Perfect for anyone looking to deepen their knowledge of computer and communication technologies.