15.4.5 Packet Forwarding In Perspective
Although routers are often viewed as complex devices, their fundamental task is remarkably simple. They examine the destination IP address of each packet and forward it toward the appropriate next network.
The complexity of the Internet arises not from the forwarding process itself, but from the enormous number of interconnected networks through which packets may travel. Every router performs the same basic function, allowing billions of devices to communicate using a common network-layer protocol despite employing many different physical communication technologies.
The following section examines how routers determine the best path through an internetwork by constructing and maintaining routing tables.
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