On the Open Systems Interconnection, OSI, reference model, the Internet Protocol, IP, resides on layer three, which is called the Network layer. The Transport Control Protocol, TCP, resides on layer four, which is called the Transport layer. The OSI reference model has seven layers that are divided into two groups called the upper layers and the lower layers.
The OSI reference model outlines how applications and devices should communicate: It divides all processes required for effective communications into logical groups called layers.
The first three layers are called the upper layers and define how software and applications communicate with each other and users. The Network layer is responsible for tracking and addressing devices on a network. This layer determines the best route to move data between devices that are not locally attached to each other, by sending a data packet to the destination device.
The last four layers are called bottom layers, and they control data that is transmitted between devices in a network. The Transport layer segments and reassembles data into a data stream. This layer provides end-to-end data transport services, such as establishing logical connections between the sending device and the destination device. It also hides details of any network-dependent information from higher layers by providing transparent data transfer.