Page 751 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

Transport Layer Security (TLS)

Session Layer

The Session layer (layer 5) is responsible for establishing,
maintaining, and terminating communication sessions between two

computers. It manages dialogue discipline or dialogue control
(simplex, half-duplex, full-duplex), establishes checkpoints for
grouping and recovery, and retransmits PDUs that have failed or been
lost since the last verified checkpoint. The following protocols operate
within the Session layer:

Network File System (NFS)

Structured Query Language (SQL)

Remote Procedure Call (RPC)

Communication sessions can operate in one of three different
discipline or control modes:

Simplex One-way communication

Half-Duplex Two-way communication, but only one direction can
send data at a time

Full-Duplex Two-way communication, in which data can be sent in

both directions simultaneously

Presentation Layer

The Presentation layer (layer 6) is responsible for transforming data
received from the Application layer into a format that any system
following the OSI model can understand. It imposes common or
standardized structure and formatting rules onto the data. The
Presentation layer is also responsible for encryption and compression.
Thus, it acts as an interface between the network and applications.

This layer is what allows various applications to interact over a
network, and it does so by ensuring that the data formats are
supported by both systems. Most file or data formats operate within
this layer. This includes formats for images, video, sound, documents,
email, web pages, control sessions, and so on. The following list