Network Models | What is protocol layering ? Principles of Protocol Layering

Network Models :

What is term protocol ?
protocol defines the rules that both the sender and receiver and all intermediate devices need to follow to be able to communicate effectively. 

 why use protocols in networking ?
When communication is simple :
we may need only one simple protocol .
when the communication is complex :
we may need to divide the task between different layers, in which case we need a protocol at each layer, or protocol layering protocol layering .

What is protocol layering ?
 Protocol layering enables us to divide a complex task into several smaller and simpler tasks.

What is the importance of protocol layering?
Why do we use layering?
Protocol layering enables us to divide a complex task into several smaller and simpler tasks.

What is the advantages of protocol layering ?

• One of the advantages of protocol layering is that it allows us to separate the services from the implementation.
• A layer needs to be able to receive a set of services from the lower layer and to give the services to the upper layer .
• Another advantage of protocol layering :
• is that communication does not always use only two end systems; there are intermediate systems that need only some layers, but not all layers.
•  If we did not use protocol layering, we would have to make each intermediate system as complex as the end systems, which makes the whole system more expensive.

 Is there any disadvantage to protocol layering?
One can argue that having a single layer makes the job easier.
There is no need for each layer to provide a service to the upper layer and give service to the lower layer.

Principles of Protocol Layering :

What are Principles of Protocol Layering ?
1__First Principle:
The first principle dictates that if we want bidirectional communication, we need to
make each layer so that it is able to perform two opposite tasks, one in each direction.

2__Second Principle:
The second principle that we need to follow in protocol layering is that the two
objects under each layer at both sites should be identical.

What is Logical Connections :
 logical connection between each layer .


This means that we have layer-to-layer communication.
Maria and Ann can think that there is a logical (imaginary) connection at each layer through which they can send the object created from that layer.

We will see that the concept of logical connection will help us better understand the task of layering we encounter in data communication and networking.

  😉 thank you all my friends 😐