The OSI Model

In the beginning, when man discovered computer networks and its importance... there was chaos. Different brilliant people created their own brilliant ways of sending data electronically from one computer to another computer. As an end result, computers made from one vendor could not directly communicate with computers made from a different vendor for they do not follow the same communication protocols. A protocol is a set of rules or an agreement that determines the format and transmission of data.

With this the ISO (International Organization for Standardization) passed a standard to different vendors a set of standards that ensure greater compatibility and interoperability of various computer network devices.

This new standard is called the Open System Interconnection Model (or OSI Model or commonly known as the 7 OSI Layers).

The 7 OSI Layers:

1. Physical


2. Data Link


3. Network


4. Transport


5. Session


6. Presentation


7. Application

The benefits of the OSI Model are:

• It reduces complexity of the entire computer network design by slicing it into 7 different areas. You can then set your focus to one area instead of the whole computer network system.


• It standardizes interfaces. You can now clearly determine which type of interface you are going to adopt for your network so that all computers can commuication with each other without problems.


• It facilitates modular engineering for you can now focus your design to one particular layer at a time.


• While one particular vendor focuses only its development or enhancements to a particular layer, others can also enhance other layers. Thus accelerates the evolution of computer networks.


• Lastly, since it reduces the complexity of the design, it also simplifies the teaching and learning of computer networking.