Network Topologies, Classifications, and Signal Concepts

Posted on Aug 21, 2024 in Computers

Network Topologies

Star Topology

  • All devices are connected to a central hub or router.
  • The central node is typically a hub or switch.
  • Allows for quick communication between nodes.
  • If the central node fails, the entire network is disconnected.

Extended Star Topology

  • Used when more connections are needed than a single star topology can provide.
  • Similar to the star topology, but each node connected to the central node can also act as the center of another star.
  • Shorter cabling and limits the number of devices that need to connect to a single central node.
  • Hierarchical structure.

Tree Topology

  • Similar to the extended star topology but with a central node acting as a backbone.
  • The backbone link node, usually a hub or switch, branches out to other nodes.
  • The backbone link is a trunk cable with layers of branching, creating a hierarchical flow of information.
  • A host server is typically connected to the other end of the backbone link.

Full Mesh Topology

  • Each node has a direct link to every other node.
  • If one link fails, information can be rerouted through other links.
  • Allows for multiple routes for data transmission.
  • Only practical for small networks due to the high number of links required.

Irregular Topology

  • Lacks a defined pattern of links and nodes.
  • Common in networks in their early stages or those that are poorly planned.

Network Classifications Based on Scale

Local Area Network (LAN)

  • Private networks within a building or a limited area of a few kilometers.
  • Used to connect personal computers and workstations in offices and factories for resource sharing (e.g., printers, scanners).
  • Limited in size, enabling predictable transmission times and simplified administration.
  • Operate at speeds up to 1 Gbps with low latency.
  • Commonly use star and tree topologies.

Metropolitan Area Network (MAN)

  • Larger than LANs, covering a metropolitan area such as a city.
  • Can connect multiple offices or a whole city.
  • Can be private or public.
  • Span up to a few tens of kilometers and operate at speeds around 10 Gbps.

Wide Area Network (WAN)

  • Cover a large geographical area, such as a country or continent.
  • Can span hundreds of kilometers.
  • Operate at speeds close to 1 Tbps.

UD2. Media: Concepts and Requirements

Mathematical Concepts

  • Superposition Principle: The effect of multiple signals combined is equal to the sum of the effects of each signal individually: f(x + y) = f(x) + f(y)
  • Fourier Analysis: Any continuous and differentiable function can be decomposed into a sum of simpler terms, often represented as an infinite series of sine waves. This series is infinite for periodic functions and becomes an integral for non-periodic functions.

Sine Signals

  • Mathematical notation: f(t) = am * sin(ωt + φ)
  • t: Independent variable representing time (seconds).
  • ω: Angular frequency (radians/second).
  • φ: Phase shift (degrees or radians; 360° = 2π radians).
  • Example: f (frequency) = 50 Hz = 50 cycles per second, ω = 2π * f = 100π rad/sec.
  • am: Maximum signal amplitude.
  • F = ω / 2π: Frequency. Number of cycles per second (Hertz).
  • T = 2π / ω: Period. Time to complete one cycle (seconds).
  • φ: Phase. Horizontal shift of the signal (radians).
  • Sine signals are periodic with a period of 2π radians.