the open systems interconnection model (osi model) is a
a layer serves the layer above it and is served by the layer below it. for example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that constitute the contents of that path. two instances at the same layer are visualized as connected by a horizontal connection in that layer.
the model is a product of the open systems interconnection project at the