The J277 Specification requires you to have an understanding of what layers are and why they are used.
You do not need to learn specific layers or their purpose.
What Are Layers?
Protocols are broken-down into layers. Each layer has one specific job. When its job is done, it passes the result down to the next layer.
When the data has passed through all the layers, it will be ready to be transmitted.
When data is received, it is passed up the layers until is has been returned to its original format.
This example shows the TCP/IP layers. It may help you to understand the concept, but you do not need to learn these layers or their purpose.
Why Use Layers?
- Breaking-down tasks into smaller parts makes them easier to design and understand
- It is easier to find and fix problems
- Changes to one layer do not affect the other layers
- Different developers can create or edit layers independently of each other
Layers are a good example of abstraction, which will be looked at in Topic 2.1: Algorithms.
Example
Looking at the diagram near the top of the page, if one of the layers needed to be updated, it could be worked on without needing to interfere with any of the other layers.