Data transport

                          Data transport process

Transport data by last two layer of osi-

Sure! Here’s an overview of both the Application Layer and the Presentation Layer within the context of the OSI (Open Systems Interconnection) model:

OSI Model Overview-

The OSI model is a conceptual framework used to understand and implement network communications. It divides network communication into seven layers, each with specific functions. From top to bottom, these layers are:

1. Application Layer

2. Presentation Layer

3. Session Layer

4. Transport Layer

5. Network Layer

6. Data Link Layer

7. Physical Layer

### Application Layer

**Position:** The 7th (top) layer of the OSI model.

**Function:** The Application Layer serves as the interface between the end-user applications and the network. It provides network services directly to user applications. This layer is responsible for:

- **Providing network services:** Such as file transfer, email, remote login, and data sharing.

- **User interface:** Facilitating communication between software applications and the network.

- **Resource sharing:** Enabling different applications to access network resources.

**Protocols and Services:**

- **HTTP/HTTPS:** Hypertext Transfer Protocol (Secure) used for web browsing.

- **FTP:** File Transfer Protocol used for transferring files.

- **SMTP/IMAP/POP3:** Protocols used for sending and receiving emails.

- **DNS:** Domain Name System, which translates human-readable domain names to IP addresses.

- **Telnet/SSH:** Protocols for remote login.

**Examples:**

- Web browsers

- Email clients

- File transfer tools

### Presentation Layer

**Position:** The 6th layer of the OSI model, just below the Application Layer.

**Function:** The Presentation Layer is responsible for the translation, encryption, and compression of data. It ensures that the data sent by the Application Layer of one system can be read by the Application Layer of another. Key functions include:

- **Translation:** Converts data from application formats to network formats and vice versa (e.g., character encoding).

- **Encryption/Decryption:** Ensures secure data transmission by encrypting data before transmission and decrypting it upon arrival.

- **Compression/Decompression:** Reduces the size of data to be transmitted, improving transmission speed and efficiency.

**Protocols and Services:**

- **SSL/TLS:** Secure Sockets Layer and Transport Layer Security for secure data transmission.

- **JPEG, GIF, PNG:** Image formats and their encoding/decoding processes.

- **MPEG, MP3:** Formats and protocols for audio and video data compression and transmission.

**Examples:**

- Data encryption tools

- File format converters

- Compression tools like ZIP and RAR

Summary

The Application Layer and the Presentation Layer play crucial roles in network communications. The Application Layer interfaces directly with user applications, providing necessary services and protocols for communication. The Presentation Layer ensures that the data is in a readable and secure format, handling translation, encryption, and compression.