The network layer supervises the handling of the packets by the underlying physical networks. We define this handling as the delivery of a packet.
Direct Versus Indirect Delivery
The delivery of a packet to its final destination is accomplished by using two different methods of delivery, direct and indirect
In a direct delivery, the final destination of the packet is a host connected to the same physical network as the deliverer. Direct delivery occurs when the source and destination of the packet are located on the same physical network or when the delivery is between the last router and the destination host. The sender can easily determine if the delivery is direct. It can extract the network address of the destination (using the mask) and compare this address with the addresses of the networks to which it is connected. If a match is found, the delivery is direct.
If the destination host is not on the same network as the deliverer, the packet is delivered indirectly. In an indirect delivery, the packet goes from router to router until it reaches the one connected to the same physical network as its final destination.