Basic Concept OSI Layer

Every people who wants to join in networking world must understand what is OSI layer.
we must overcome this concept, because OSI layer is the basic in networking.

What is OSI?
OSI(Open Systems Interconnection) is model product of OSI effort at the ISO. OSI is a resolution of standard and characteristic of a communications system in terms of abstraction layer.
which mean OSI is a model abstraction to help us know and differentiate the function network device and the system work.

OSI layer is consist of 7 layer:
1. Application Layer
2. Presentation Layer
3. Session Layer
4. Transport Layer
5. Network Layer
6. Data Link Layer
7. Physical layer

Every layer has own specific responsibility for process data communication.
For example, one layer has responsibility to create connection between each other media, and the other layer has responsibility to correct if “error” happen during transfer data.
There are a few theory about this OSI layer. Some people difference this 7 layer in two groups (Upper Layer and Lower layer).
Upper layer is consist of Application Layer, Presentation Layer, Session layer.
Lower layer is consist of Transport layer, Network Layer, Data Link layer, Physical layer.

Upper layer is describe on application that user use and how the file being represented on computer.
For network engineer, the main part is lower layer.
lower layer is the main of data communication.

The main purpose of using model OSI is to help network desainer to understand function of each layer that have connection with communication data flow. Include type of network protocol and method of transmission

I will describe the function of each layer in other subject.
May this post can help u understand the OSI layer.