JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III COMPUTER NETWORKS Previous Question Paper (February - 2022 - R18)

The OSI model is a conceptual framework that defines seven layers, while the TCP/IP model is a practical implementation with four layers. Key differences include:

• Layer Structure: OSI has 7 layers (Physical, Data Link, Network, Transport, Session, Presentation, Application), whereas TCP/IP merges the top three OSI layers into one Application layer and the bottom two into a Network Access layer.
• Approach: OSI was developed as a theoretical standard, while TCP/IP was developed based on existing protocols.
• Reliability: OSI defines both connection-oriented and connectionless communication at the Network layer, while TCP/IP supports connectionless at the Network layer and both at the Transport layer.
• Flexibility: TCP/IP is more robust and widely used in modern internet architecture compared to the more rigid OSI model.

Transmission media are the physical paths between transmitters and receivers. They are categorized into two main types:

1. Guided Media (Wired): Signals are directed along a physical path.
   • Twisted Pair: Consists of two insulated copper wires twisted together to reduce crosstalk and electromagnetic interference. Used in telephone lines and LANs.
   • Coaxial Cable: Features a central conductor, an insulating layer, a metallic shield, and an outer jacket. It provides high bandwidth and better noise immunity, used for cable TV and broadband.
   • Fiber Optics: Uses light pulses through glass or plastic cores to transmit data. It offers extremely high bandwidth, low attenuation, and immunity to electromagnetic interference.
2. Unguided Media (Wireless): Signals are transmitted through free space using electromagnetic waves, including radio waves, microwaves, and infrared.

A conceptual sketch involves a source device connected to a destination device via a medium, where guided media are represented by lines (cables) and unguided media are represented by waves radiating through the air.