OSI Layer 6: Presentation Layer

Definition

The Presentation Layer (sometimes called the Syntax Layer) acts as the data translator between the application format and the standard network transmission format. It ensures that data sent from the application layer of one system is readable by the application layer of another.

Key Functions

1. Data Translation & Formatting: Converting character encodings (e.g., ASCII, EBCDIC, UTF-8).
2. Encryption & Decryption: Securing data before transmission and decrypting upon receipt (TLS/SSL cryptographic operations).
3. Data Compression: Reducing the volume of data transmitted over the network (Gzip, Deflate, JPEG, MPEG).
4. Serialization: Formatting complex objects (JSON, Protocol Buffers, ASN.1).

Protocol Data Unit (PDU)

• Data / Formatted Data

Adjacent Layers

• Receives data from OSI Layer 7: Application Layer and passes formatted data to OSI Layer 5: Session Layer.