What is the abstraction for processes at the application layer to connect to the network via the transport layer?

The abstraction for processes at the application layer to connect to the network via the transport layer is known as a socket.

Here are the steps to explain this:

1. The application layer is the topmost layer in the OSI model, which provides services to the software applications so they can communicate with other applications on a network. The application layer doesn't transmit data, it's used for setting up, managing, and terminating communication sessions.

2. The transport layer is responsible for end-to-end communication over the network. It provides services such as connection-oriented data stream support, reliability, flow control, and multiplexing.

3. A socket is an endpoint in a communication flow between two programs running over a network. Sockets provide a programming interface for network communication. In the context of the internet protocol suite, they are an abstraction layer between the transport layer and the application layer.

4. When an application wants to send or receive traffic, it opens a socket, which, in turn, has a specific port number. This socket is then bound to the IP address of the machine where the application is running.

5. The combination of an IP address and a port number is known as a socket address, and this is what allows the transport layer to deliver data to the correct application.

6. Therefore, the socket serves as the abstraction for the process at the application layer to connect to the network via the transport layer.