While the link layer is responsible for transferring packets between nodes that are directly linked, the network layer transfers packets between nodes that are not directly linked and might belong to different networks.

Functionalities that help to provide network layer service

The functionalities that help the network layer transfer packets between nodes, which are not directly linked and may belong to different networks, can be divided into two main areas: the control plane and the data plane.

Control plane

The control plane is the part of the network layer that gathers all the necessary meta-information, which is needed to route data packets between nodes.

Data plane

The data plane is the part of the network layer that routes data packets between nodes, while leveraging information provided by the control plane.

Protocols

Note: There are many different protocols that are followed inside the network layer, but it is impractical to cover them all in this lesson. Hence, we will focus on the most central ones in this course.

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