Communication Networks -14 -Application and Presentation Layers.pdfVIP

Module 4 Standards Version 1 ECE , IIT Kharagpur Lesson 14 Application Presentation Layers Version 1 ECE , IIT Kharagpur LESSON OBJECTIVE General This lesson is designed to give the reader an overview of the standards followed in the topmost layers of the OSI reference model viz. Application layer and Presentation layer. Specific On completion of this lesson, the learner shall be able to 1. Understand the working of Telnet protocol. 2. Identify the applications of FTP. 3. Outline the procedure of HTTP. 4.7.1 INTRODUCTION This lesson continues our exploration of networking standards by examining high level internet services and the application and presentation layer standards that support them. These services determine how users pursue the internet. We will see that these high level services provide increased communication functionality and allow users and programs to interact with automated services on remote machines and with remote users. We shall now look at TELNET, FTP and HTTP in detail. 4.7.2 TELNET PROTOCOL The TCP/IP protocol suite includes a simple remote terminal protocol called TELNET that allows users to log in to a computer across the internet. TELNET establishes a TCP connection and then passes keystrokes from the user’s keyboard directly to the remote computer as if they had been typed on a keyboard attached to the machine. TELNET also carries output from the remote machine back to the user’s sc