In packet-switched networks, end-to-end connections between two terminals are established by transmitting data packets from a sending station to a receiving station. The stations must be uniquely identifiable via their network addresses.
Between the two stations are routers that forward the data packets according to their routing tables from the sending station via the first router to the second, to the third, and so on, until the last router delivers the data packets to the receiving station on their way through the data packet network.
Routing tables are created by routing protocols for path discovery and may vary depending on the routing protocol. In static routing, the routing path is fixed. The routing table contains the destination address of the network, the subnet mask, the addresses of the gateway and the interface. In dynamic ro uting, the routing tables are updated by current routing information. The updating is done by routing protocols that enter the information. This can be information about the links of the networks, or the end devices and the hops with the IP addresses belonging to them, or the routing metrics with which the route was defined.