TCP/IP Model and OSI Model

The TCP/IP model and the OSI model are two different models used to describe network communication. The TCP/IP model is used for the internet and the OSI model is used for general communication. Both models have layers that describe the different aspects of network communication.

Layers of TCP/IP Model

The TCP/IP model has four layers, which are as follows:

1. Application Layer: The Application Layer is responsible for providing services to the user. It includes protocols such as HTTP, FTP, SMTP, and Telnet.

2. Transport Layer: The Transport Layer is responsible for providing reliable communication between applications. It includes protocols such as TCP and UDP.

3. Internet Layer: The Internet Layer is responsible for providing logical addressing and routing of packets. It includes protocols such as IP, ICMP, and ARP.

4. Network Interface Layer: The Network Interface Layer is responsible for providing physical addressing and access to the network media. It includes protocols such as Ethernet and Wi-Fi.

Layers of OSI Model

The OSI Model has seven layers, which are as follows:

1. Application Layer: The Application Layer is responsible for providing services to the user. It includes protocols such as HTTP, FTP, SMTP, and Telnet.

2. Presentation Layer: The Presentation Layer is responsible for translating data from the application layer into a format that can be understood by the network. It includes protocols such as JPEG and MPEG.

3. Session Layer: The Session Layer is responsible for establishing, maintaining, and terminating sessions between applications. It includes protocols such as NetBIOS and RPC.

4. Transport Layer: The Transport Layer is responsible for providing reliable communication between applications. It includes protocols such as TCP and UDP.

5. Network Layer: The Network Layer is responsible for providing logical addressing and routing of packets. It includes protocols such as IP, ICMP, and ARP.

6. Data Link Layer: The Data Link Layer is responsible for providing physical addressing and access to the network media. It includes protocols such as Ethernet and Wi-Fi.

7. Physical Layer: The Physical Layer is responsible for transmitting raw data over a physical medium. It includes protocols such as RS-232 and V.35.

Missing Layer in TCP/IP Model

The Session Layer is missing in the TCP/IP model. This layer is responsible for establishing, maintaining, and terminating sessions between applications. The TCP/IP model does not have this layer because it assumes that the applications will handle these functions themselves. However, some TCP/IP protocols such as FTP and Telnet perform session management functions at the application layer.

Conclusion

In conclusion, the TCP/IP model and the OSI model are two different models used to describe network communication. The TCP/IP model has four layers, while the OSI model has seven layers. The Session Layer is missing in the TCP/IP model, but some protocols perform session management functions at the application layer.