Layer 3, the OSI model’s network layer, is also known as logical addresses. This layer provides an end-to-end logical addressing mechanism allowing a data packet to be routed over several Layer 2 networks (Ethernet, Token Ring, Frame Relay, etc.).
In bigger systems, there are frequently intermediate nodes between any two end systems. The network layer provides the link that allows the layers above to deliver packets regardless of whether the end system is on the local LAN or several hops distant. Routers and gateways are network layer devices.