Endsystems

Endsystems, also known as hosts, are the devices that initiate or receive data in a network. They are the source and destination points of network communication. Examples of endsystems include computers, smartphones, servers, and the Internet of Things (IoT) devices. These devices run applications that generate or consume the network traffic.

The primary role of an endsystem is to provide services to users or other endsystems. For instance, a web server endsystem hosts websites and serves them to client endsystems, such as web browsers running on laptops or smartphones. Similarly, a mail server endsystem handles the sending and receiving of emails for its users. The operating system of an endsystem plays a crucial role in managing network resources and running the applications that facilitate communication.

Endsystems interact with the network through network interface controllers (NICs) and software protocols. When an endsystem needs to send data, it typically uses application-layer protocols to format the data and then passes it down through the transport layer and network layer protocols for addressing and routing. The data is then sent over the physical network medium. Conversely, when an endsystem receives data, it passes through the network layers in reverse order, with the application layer ultimately processing the data. The specific protocols used depend on the type of communication and the applications involved.