Answer :

The TCP$/$IP and OSI network models are both conceptual frameworks used to understand and design network protocols. Here are the key differences between them:

TCP$/$IP Model:

$$ Definition: A four$-$layer model developed by the Department of Defense to ensure reliable data transmission over the internet.

$$ Layers:

$1.$ Application Layer: Combines functionalities of OSI's Application, Presentation, and Session layers.

$2.$ Transport Layer: Corresponds to OSI's Transport layer, responsible for end$-$to$-$end communication and error handling.

$3.$ Internet Layer: Maps to OSI's Network layer, handling logical addressing and routing.

$4.$ Network Interface Layer: Encompasses OSI's Data Link and Physical layers, dealing with physical transmission of data.

OSI Model:

$$ Definition: A seven$-$layer model developed by the International Organization for Standardization to standardize network communication.

$$ Layers:

$1.$ Application Layer: Interfaces directly with end$-$user applications.

$2.$ Presentation Layer: Translates data between the application layer and the network.

$3.$ Session Layer: Manages sessions between applications.

$4.$ Transport Layer: Ensures reliable data transfer.

$5.$ Network Layer: Handles logical addressing and routing.

$6.$ Data Link Layer: Manages node$-$to$-$node data transfer.

$7.$ Physical Layer: Deals with the physical connection between devices.

Differences Between TCP$/$IP and OSI Network Models

$1.$ Number of Layers:

o TCP$/$IP Model: Has $4$ layers $($Application$,$ Transport, Internet, Network Interface$).$

o OSI Model: Has $7$ layers $($Application$,$ Presentation, Session, Transport, Network, Data Link, Physical$).$

$2.$ Layer Functions:

o TCP$/$IP Model: Combines the OSI model's Application, Presentation, and Session layers into a single Application layer. The Network Interface layer in TCP$/$IP combines the OSI's Data Link and Physical layers.

o OSI Model: Each layer has a distinct function and is more granular in its approach.

$3.$ Development and Usage:

o TCP$/$IP Model: Developed by the Department of Defense $($DoD$)$ for the ARPANET and is the foundation of the Internet.

o OSI Model: Developed by the International Organization for Standardization $($ISO$)$ as a theoretical framework to standardize networking protocols.

$4.$ Protocol Dependency:

o TCP$/$IP Model: Protocols are defined within the model itself $($e$.$g$.,$ TCP$,$ IP$).$

o OSI Model: Protocols are not specified within the model; it is a guideline for creating interoperable network protocols.

$5.$ Flexibility and Implementation:

o TCP$/$IP Model: More flexible and widely implemented in real$-$world networking.

o OSI Model: More rigid and primarily used as a reference model for understanding and designing network protocols.