The network layer addressing scheme involves assigning a logical address to a network device. The most commonly used network layer protocol for creating these addresses is the Internet protocol, or IP, which typically works in conjunction with the transmission control protocol, or TCP.
An addressing system is necessary to ensure proper delivery of network messages from one device to another. Instead of using a physical address, the network layer uses logical addresses called IP addresses to uniquely identify and access interconnected computers.
An IP address is divided into two sections: hostid and netid. Hostid corresponds to the host computer or device, while netid corresponds to the network. Computers that belong in the same network have the same netid. Complex networks are usually broken down into more manageable ones through a process known as subnetting. This method provides a transitional hierarchical level in the addressing scheme of the network layer.