The lowest level protocols are placed at the bottom, creating the foundation upon which higher levels, or coatings, are placed. The OSI Reference Model, for example, includes seven layers, each of which is interrelated, providing assistance to those above and below.
The collection of protocols used in a communications network. A protocol stack is a defined hierarchy of software layers, starting from the application layer at the top (the source of the data being sent) to the data link layer at the bottom
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