Data Communication Networks Day 1

Data Communication Network

• The presentation is about data communication networks, covering various aspects from terminology to types, physical structures, and devices.
• Day 1 of a course on this topic.

Network Terminologies

• Networking: Connecting multiple devices (computers, printers) to share information.
• Data Communication: The process of sharing information.
• Network: A collection of interconnected devices/computers/IP addresses/hosts.
• Computer Network: A group of computers connected to share information.
• Node: Any device connected to the network - computer, printer, etc.
• Network Interface Card (NIC): The circuit board connecting computers to the network (e.g., Ethernet card).

Components of Data Communication

• Protocol: Set of rules for communication.
• Sender: Device initiating transmission.
• Message: Information being sent.
• Medium: Path for transmission (e.g., cable, airwaves).
• Receiver: Device receiving information.

Need of Network/Applications of Network

• Information Sharing: Sharing data between users.
• Enhance communication: Faster and more efficient communication.
• Share resources: Sharing printers, files, etc.
• Facilitate centralized management: Managing resources centrally.
• Remote computing: Accessing resources from a distance.

Network Criteria

• Performance: Measured by delay and throughput (speed).
• Reliability: Measured by frequency of failure and time to recover.
• Security: Protecting data from corruption and malicious users.

Network Types

• Wired: Uses cables to transfer data.
  • Cable Types: Coaxial, Twisted Pair, Fiber Optics.
    • Cat1 to Cat8: Different types of copper cable with different speeds.
• Wireless: Uses electromagnetic waves for data transfer.
  • Medium: Air (EM Waves).
  • Cable types: PAN, WLAN, WAN (GSM).

Media (Transmission Medium)

• Guided: Data transmitted through physical cables (e.g., copper wires, fiber optics).
• Unguided: Data transmitted through free space (e.g., radio waves, microwaves).

Transmission Modes / Data Flow Direction

• Simplex: One-way communication (Keyboard).
• Half-Duplex: Two-way communication but not simultaneous (Walkie-talkie).
• Full-Duplex: Two-way communication simultaneously (Telephone).

Twisted Pair

• Most common in wired networks, wires are twisted for better signal transmission.
• Shielded (STP): Wires shielded against noise.
• Unshielded (UTP): Wires bundled together in a protective sheath.

Coaxial Cable

• Used for cable TV and LANs, better shielding than twisted pair, carries signals further and faster.
• Can be used for both analog and digital signals.

Optical Fiber

• Thin glass or plastic threads carrying light signals for data transmission.
• Immune to electromagnetic interference - suitable for noisy, industrial environments.
• Three Layers: Core, Cladding, Protective Buffer.

Switching

• Technique for choosing the best route for data transmission in large networks.
• Methods of Switching: Circuit, Message, Packet.

Circuit Switching

• Establishes a dedicated path between sender and receiver until the connection is terminated.
• Operates similarly to a telephone connection.

Message Switching

• No dedicated path, message routed through intermediate nodes.
• Information about the destination is part of the message's header.
• Uses store-and-forward methodology.

Packet Switching

• Messages broken into smaller packets, each transmitted individually with sequence numbers and addresses for correct assembly.
• Each packet can find the shortest path.
• Ensures packets are reassembled without error at destination.

Multiplexing

• Combining multiple signals into a single channel (e.g., combining several phone calls into a single cable).
• Methods: Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM).
  • FDM: Different frequencies used to transport different data.
  • TDM: Same channel split into time slots for different signals.

Network Classification

• Geographic: LAN (Local Area Network), MAN (Metropolitan Area Network), WAN (Wide Area Network).

• Component Roles: Peer-to-peer, server-based (client-based).

• LAN: Small geographical area (building, campus), Wired or Wireless, twisted pair, coaxial, or fiber optics.

• MAN: Larger than a LAN (city), high-speed connections (e.g., fiber optic).

• WAN: Largest (country, world), long-distance, includes Internet.

ARP (Address Resolution Protocol)

• Protocol for translating IP addresses to MAC addresses (hardware addresses) and vice-versa.
• Essential for communication between different network segments.
• Protocol that asks the destination for its address.
• Broadcast: Sending an address request to every device on a local segment.

Network Classification by Component Roles

• Possible configurations for networks: Peer-to-peer, Client Based, Server-Based.

Network Physical Structure

• Types of Connection: Point-to-point (one-to-one) / Multipoint (one-to-many).
• Physical Topology: Geometric representation of network nodes and connections; including Mesh, Star, Bus, Ring.

Network Devices / Internetworking Devices

• Hubs, Repeaters, Bridges, Switches, Routers, Gateways

Network Interface Card (NIC)

• Hardware for connecting a device to a network.
• Every NIC has a unique MAC address.
• Converts between digital and electrical signals.

Ethernet Frame Format

• Preamble, SFD, Destination MAC, Source MAC, Type, Data, FCS.