The OSI reference model is that contains a set of protocols that are used to define and provide a standard for data communication between two devices in a network (Deal, 2008). Given its international standardization, this model is supported by many vendors of computer and network equipments. The OSI reference model is composed of 7 layers with specific protocols being used in each layer making it a modular model. On the other hand, the TCP/IP model is a set of protocols that can be implemented on networks such as MANs, WANs and LANs (Ciccarelli & Faulkner, 2004). The TCP/IP protocol suite does not match the seven layers of the OSI reference model but only four of them. The two models are similar in function despite the different number of layers they have. To some extent, the TCP/IP layer is not an international layer as OSI reference model.
The use of layers in network models is critical to the attainment of some benefits.
The use of layers allows the division of communication process into simpler that that makes the network easy to design and troubleshoot. A layered network makes it possible for different computer vendors to work in a standardized development process. It also makes it possible for different network equipment to communicate with one another more easily and at the same time prevent a problem to affect the whole network (Lammle, 2007). These advantages have allowed for the use of the layered approach in building of networks.
The concept of a confirmed service and a non-confirmed service appears in regard to the communication between different layers. When layers communicate to the lower layers in the same device with the other layers in a different device, the presence of request primitive and response primitive makes such a service to be a confirmed service. However, when a layer makes use of indication and request provision, such a service is termed as a non-confirmed service (Ahmad, 2003).