Layer 6: The Presentation Layer

The Presentation Layer is responsible for managing the way that data is encoded. Not every computer system uses the same data-encoding scheme, and the Presentation Layer is responsible for providing the translation between otherwise incompatible dataencoding schemes, such as American Standard Code for Information Interchange (ASCII) and Extended Binary Coded Decimal Interchange Code (EBCDIC).

The Presentation Layer can be used to mediate differences in floating-point formats; number formats, such as one’s complement and two’s complement; and byte ordering; as well as to provide encryption and decryption services.

The Presentation Layer represents data with a common syntax and semantics. If all the nodes used and understood this common language, misunderstanding in data representation could be eliminated. An example of this common language is Abstract Syntax Representation, Rev 1 (ASN.1), an OSI recommendation. In fact, ASN.1 is used by the Simple Network Management Protocol (SNMP) to encode its high-level data.