Jawaharlal Nehru Technological University Hyderabad B.Tech IV INTERNETWORKING Previous Question Paper (July - 2021 - R15)

In the TCP/IP protocol suite, the identical objects at the sender and receiver sites for a logical connection at the application layer are known as processes. When two application-layer entities communicate, they do not communicate directly with each other; rather, they communicate through their respective operating systems using sockets.

A process is an instance of an application program running on a host. For a logical connection to be established, the following components are involved:

1. Socket Address: Each process is identified by a unique socket address, which is a combination of an IP address and a port number.
2. Client-Server Model: One process acts as the client (initiating the connection) and the other as the server (listening for connection requests).
3. Logical Communication: Although the physical data travels through various layers (Transport, Network, Data Link, and Physical), the application layer perceives a direct, logical path between the two processes.
4. Interface: The socket serves as the interface between the application process and the transport layer (TCP or UDP). The application sends data into the socket, and the transport layer handles the segmentation, addressing, and reliability required to deliver that data to the corresponding socket of the peer process.

Essentially, the application layer views the connection as a peer-to-peer exchange between two processes, abstracting away the underlying complexities of the network infrastructure.