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Interfaces Between Layers

The passing of the data and network information down through the layers of the sending device and back up through the layers of the receiving device is made possible by an interface between each pair of adjacent layers. Each interface defines the information and services a layer must provide for the layer above it. Well-defined interfaces and layer functions provide modularity to a network.

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(Fonte: Forouzan, B.A. (2007) Data Communications and Networking. 4th Edition, McGraw Hill Higher Education, New York)

I. Choose the only correct statement, according to the text: