The network layer comes after the data link layer in the OSI model. After the data link layer packages information and data, the network layer does its part by sending this package across the network. There are several different ways in which protocols in the network layer make this sending of data possible.
Because the term “data” can feel a little too abstract and be hard to visualize, let’s think of the network layer in terms that everyone can understand. We all know the tale of Little Red Riding Hood, the little girl who was plagued by a wolf on her trip to her grandmother’s house. Let’s imagine you are Little Red Riding Hood, and you’ve been given a letter to take to your grandmother. We can do away the wolf (sorry, our example can’t be that exciting), but we can keep everything else.
When you are given this letter and charged with its delivery, you are like the network layer. The network layer is charged with sending off information in an intelligent and efficient manner. What does this really mean? Let’s look at it again.
When you get the letter to take to your grandmother’s, the first thing you may do is look and double check the address. This is what the network layer does, as it determines where data must be sent across the network. What next? What would you do?
Like most people, the first thing you’d probably do is determine the fastest and most efficient route to get to your grandmother’s house. The network layer also is in charge of this responsibility, as it makes sure that data transmitted over the network travels in the fastest route possible. In order to do this, it uses a process called “discovery” to gather information across the network and determine the best path for the information to take.
And, finally, let’s imagine that when you get to your grandmother’s home, the letter is too thick to go through her mail slot. Because you don’t want to leave it outside, and she won’t answer her door, you decide that you will use a second envelope and break the letter into two smaller letters that can fit through the door.
The network layer also does this. Because some computers cannot receive data at the same rate as others can send it, the network layer also is charged with the task of breaking data into smaller pieces that can be accepted by the receiving computer. In this way, the network layer functions to send data.