Topology Overview: Mesh and Star Topologies

May 31, 2024

Lecture on Topology

Introduction to Topology

  • Topology describes the arrangement of devices in a network.
  • Common types: Mesh, Star, Bus, Ring, Hybrid.
  • Important for UGC NET exams.
  • Simple concept, but questions can be tricky.

Mesh Topology

Features

  • All devices are interconnected.
  • Diagram example with 4 devices and extended to 5 devices.

Important Questions

  1. Number of Cables
    • Formula: nC2 or n(n-1)/2
    • Example: 4 devices → 6 cables. For 10 devices → 45 cables.
  2. Number of Ports
    • Formula for each device: n - 1
    • Example: 4 devices → 3 ports each. For 5 devices → 4 ports each.
    • Total number of ports: n(n-1).
  3. Reliability
    • Mesh topology is highly reliable.
    • Multiple paths for data transfer.
    • High reliability compared to other topologies.
  4. Cost
    • High due to large number of cables.
    • Example: 10 devices require 45 cables.
  5. Security
    • High security since communication is direct and isolated.
  6. Maintenance
    • High maintenance due to numerous cables.

Communication Type

  • Supports point-to-point communication.
  • No sharing of cables between devices.

Star Topology (Hub Topology)

Features

  • Centralized device called Hub.
  • Hub is a multi-port device.
  • Devices connected through the hub.

Important Questions

  1. Number of Cables
    • N cables for N devices.
    • Example: 4 devices → 4 cables.
  2. Number of Ports
    • One port per device.
    • Example: 4 devices → 1 port each.
    • Total ports: n.
  3. Reliability
    • Single point of failure (hub).
    • Less reliable as compared to Mesh.
  4. Cost
    • Less than Mesh due to fewer cables.
    • Hub cost is significant but overall less than Mesh.
  5. Security
    • Security can be configured but by default, hub broadcasts to all devices.
    • Generally less secure compared to Mesh.

Communication Type

  • Supports point-to-point communication.
  • No sharing of cables between devices.

Conclusion

  • Discussed Mesh and Star topologies.
  • Upcoming lecture on other topologies.

References

  • Video link for more information about the hub.