We know that the route lookup process is the process of finding the next hop for a data packet! IP routing forwards packets hop-by-hop toward the destination. The so-called next hop is the corresponding interface IP address of a router directly connected to the current one. This is a logical understanding. However, IP routing provides another method: the next hop does not necessarily have to be directly connected. It can ignore the “nearby topology” of the current router and directly point to a relatively distant topology, as shown in the figure below:
