The previous unit was a study of the data plane of the network layer. We learned how a transport layer segment is put into a packet for transmission from origin to destination, and how a packet is forwarded to the next hop.
Unit 5 deals with the control plane of the network layer. It illustrates how a transport layer segment is routed among routers from origin to destination. It also discusses a variety of routing algorithms and how network layer components and services are configured and managed.