JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA 2022 COMPUTER NETWORKS Previous Question Paper (March/April - 2022 - R17)

The OSI (Open Systems Interconnection) model and the TCP/IP (Transmission Control Protocol/Internet Protocol) model are both conceptual frameworks used to describe network communication, but they differ in design philosophy, layering, and practical implementation.

Key differences include:

• Layering Structure: The OSI model is a strict 7-layer reference model, whereas TCP/IP is a 4-layer model that collapses the top three OSI layers (Application, Presentation, Session) into a single Application layer and the bottom two (Data Link, Physical) into a Network Access layer.
• Design Philosophy: OSI was created as a generic, protocol-independent standard to facilitate interoperability between different systems. TCP/IP was designed specifically for the ARPANET and the modern Internet, prioritizing practical implementation and robustness over strict theoretical layering.
• Protocol Dependency: The OSI model is protocol-independent, serving as a guideline for designing networks. The TCP/IP model is protocol-dependent, as it was built specifically around the TCP and IP protocol suite.
• Usage: The OSI model is primarily used as a pedagogical tool for understanding network architecture and troubleshooting. The TCP/IP model is the actual architecture that powers the global Internet and modern networking hardware.

Transmission media are the physical pathways used to carry information from a sender to a receiver. They are broadly categorized into guided (wired) and unguided (wireless) media.

1. Guided Media (Wired)

• Twisted Pair Cable: Consists of two insulated copper wires twisted together.
  Merits: Inexpensive, easy to install.
  Demerits: Susceptible to electromagnetic interference, limited bandwidth and distance.
• Coaxial Cable: Consists of a central conductor surrounded by an insulating layer and a metallic shield.
  Merits: Higher bandwidth than twisted pair, better noise immunity.
  Demerits: Bulky, more expensive than twisted pair.
• Fiber Optic Cable: Uses light pulses through glass or plastic cores.
  Merits: Extremely high bandwidth, immune to electromagnetic interference, low signal attenuation.
  Demerits: Expensive, requires specialized installation and fragile handling.

2. Unguided Media (Wireless)

• Radio Waves: Omnidirectional waves used for long-distance communication (e.g., AM/FM radio).
  Merits: Can travel long distances, penetrates buildings.
  Demerits: Susceptible to interference, limited security.
• Microwaves: Unidirectional waves used for point-to-point communication.
  Merits: High data rates, suitable for long-distance terrestrial and satellite links.
  Demerits: Line-of-sight required, affected by weather conditions.
• Infrared: Short-range communication used for line-of-sight applications (e.g., remote controls).
  Merits: Secure within a room, no licensing required.
  Demerits: Cannot penetrate walls, limited range, affected by sunlight.