Ch 13 14 Session and Presentation Layers Laboratorium

Ch 13 & 14. Session and Presentation Layers Laboratorium Telematika - ITB Cisco Regional Networking Academy Semester 1 Version 2. 1. 1 Duration: 30 minutes

Overview n Session Layer n Presentation Layer

Session Layer Functions n n Establishes, manages, and terminates sessions between applications. Starting, stopping, and resynchronizing sessions (dialogue separation).

Two Modes of Communication n Two-way alternate communication. u The two parties take turns sending messages to avoid interrupting each other. u Determining which role to play is called dialogue control. n Two-way simultaneous communication. u The two parties talk whenever it wishes. u Receiver always assume that more information is always on the way.

Dialogue Separation n n Dialogue separation is the orderly initiation, termination, and managing of communication. Checkpoints are used for synchronization. u Auto. Saving a word processor document periodically is a form of checkpoint. n Two very important checkpoints: u Orderly initiation -- to start a session u Termination of the conversation -- to end a session.

Session Layer Protocols

Presentation Layer Functions n Allows communication between applications on diverse computer systems in a manner that's transparent to the applications.

Three Main Functions n Data formatting u Example: Extended Binary Coded Decimal Interchange Code (EBCDIC), American Standard Code for Information Interchange (ASCII), and Unicode. n Data encryption u Example: Pretty Good Privacy (PGP), Privacy Enhanced Mail (PEM), and Secure MIME. n Data compression u Example: ZIP, RAR, Stac, and V. 42 bis

Presentation Layer Formats n The Presentation Layer translates between different representations.

Hypertext Markup Language (HTML) n A format language to create web pages. u Directs a Web browser on a particular Web page to produce the appearance of the page in a specific manner. u Specifies locations for the placement of text, files, and objects that are to be transferred from the Web server to the Web browser.

The End