The reference model is a term used in software engineering which is a framework to help a better communication between networks. This is done by professionals who have knowledge in this field and consists of clearly stated instructions on how the system should work. It explains the whole structure or an important part of the structure at one time but represents the entire model in the end. It also has many terms which are commonly used while implementing the model, which itself can be of two different types known as OSI model and TCP/IP reference model. Both of them are distinct from each other although they perform the same task. The main difference between them is the name, OSI is called Open System Interconnection while TCP/IP is known as Transmission Control Protocol / Internet Protocol. There are three different upper layers in OSI which are an application, presentation, and session while there is only one such layer is TCP/IP, which is the application. The primary role of session layer in OSI is allowing two different entities to hold a conference between them, this is not possible with TCP/IP since these functions exist in the transport layer and same is the case with the presentation layer. Both of them have a different application layer, for OSI it is present in the 7th layer which is the top most, while TCP/IP has it at the upper part because it is the only tier. OSI uses FTAM, VT, MHS for the application layer while TCP/IP uses FTP, SMTP, TELNET, and DNS for the application layer. The structure of the system is different too, for the OSI there is a common application development infrastructure along with the traditional transport services present on each other which are connected to the application layer. For TCP/IP, there is only the standard transport service current which is directly related to the application ports. The ISO approach is known as the horizontal approach while TCP/IP method is called the vertical approach only the parts which perform the function are placed on each other. Some other differences between them and explanation are given in the paragraphs below.
Definition of OSI
This is known as the horizontal approach in which there are different layers such as presentation, session and application layers. The system works as a reference for other applications and does not implement any action itself, instead gives a set of guidance related to the function, therefore, it is not considered as reliable. All the layers play an important role and perform different jobs, and there is a total of 7 layers among which the application layer is the top most.
Definition of TCP/IP
This is known as the vertical approach and stands for Transmission Control Protocol / Internet Protocol. It does not have many layers and the application layer perform the core functions since presentation and session ones are absent. There are specific protocols which are present and cannot be replaced. It implements all the instructions itself through the transfer of package it not guaranteed through the transfer layer still it is regarded as the most reliable among the current systems.
Differences in a Nutshell
- OSI is known as the horizontal approach while TCP/IP is known as the vertical approach.
- There are seven different layers in the OSI model while the number of layers for TCP/IP model are four.
- OSI is independent of protocols and is generic, while TCP/IP has standard rules which help in developing the internet.
- TCP/IP model is more reliable than the OSI model.
- The packages are delivered to the transport layer of OSI while this is not an assured thing in the case of TCP/IP.
- There is a presentation and session layer in OSI model while no such layer exists in the TCP/IP model.
- OSI helps in guiding the network and acts as a reference tool while TCP/IP implements the functions which run the system.
- TCP/IP provides connectionless services through the network layer while the network layer for OSI provides both connection and connectionless services.
- TCP/IP does not fit in any other model while OSI tries to fit in other models because it is a reference.
- All the functions are distinctively separated in the OSI model while it is the opposite in TCP/IP model.
- Protocols can easily be terminated, and new ones can be introduced in the OSI model while original rules stay in the TCP/IP model.
All in all, it can be said that the three terms that have been explained above are very different from each other in the way they are used, and their origins. This article has therefore given a proper explanation of the terms so that people are able to use them properly.