# Upper OSI Layers

They are more relevant to application developers rather then network engineers.

# Layer 7 – Application Layer

It provides network services to the applications of the user. It establishes the availability of communication partners. It then synchronizes and establishes agreement on procedures for error recovery and control of data integrity.

It doesn’t include any layer.

# Layer 6 – Presentation Layer

It ensures that the information that is sent by the application layer of one system is readable by the application layer of another system: for example, it can translate among multiple data formats using a common format.

It contains layer 7.

# Layer 5 – Session Layer

It establishes, manages and terminates sessions between two communicating hosts. It also synchronizes dialog between layer 6 of the two hosts and manages their data exchange.

It also offers efficient data transfer, Class of Service (CoS) and exception reporting of upper layers problems.

It is contained by layer 5 and it contains layer 6.