What are the steps of encapsulation?

Answer 1

Encapsulation is the process of adding header information to the layers' data "payload". As the "payload" is passed from one TCP/IP (or OSI) layer to the next, encapsulating layer information is wrapped around the data. So, for example, if the application layer produces a data payload for transmission, it encapsulates it with application-layers headers, which then gets passed to the presentation layer. The presentation layer does the same and so down the protocol stack before transmission across the physical media. At the destination, the process is reversed by way of de-encapsulation where the headers are stripped-off by each matching layer at the destination.

1. Application, Presentation and Session layers create data. {Encapsulation headers added by layers}

2. Transport layer coverts data into segments for transport across the network. {Encapsulation headers added by layer}

3. Network layer converts segments into packets (or Datagrams). {Encapsulation headers added by layer}

4. Data Link layer converts packets (and datagrams) into Frames and the Data Link header is added. {Encapsulation headers added by layer}

5. Physical - frames are converted into bits for transmission over the physical media.{Encapsulation headers added by layer}

Answer 2

The ability to make changes in your code without breaking the code of all others who use your code is a key benefit of encapsulation. You should always hide implementation details. To elaborate, you must always have your variables as private and then have a set of public methods that others can use to access your variables. Since the methods are public anyone can access them, but since they are in your class you can ensure that the code works the way that is best for you. So in a situation that you want to alter your code, all you have to do is modify your methods. No one gets hurt because i am just using your method names in my code and the code inside your method doesnt bother me much.