Explain network layer in details.

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  Solution :-

 Network layer:

  • The network layer in a network model is responsible for the source-to-destination delivery of a packet, possibly across multiple network models (links). 
  • The network layer in a network model ensures that each packet gets from its point of origin to its final destination.
  • If two systems are connected to the same link, there is usually no need for a network layer in a network model. 
  • However, if the two systems are attached to different network models (links) with connecting devices between the network models (links), there is often a need for the network layer in network model to accomplish source-to-destination delivery. 
  • Following Figure shows the relationship of the network layer to the data link and transport layers in a network model.
        Figure: Network layer in a network model

  • The network layer in a network model is responsible for the delivery of individual packets from the source host to the destination host.
Other responsibilities of the network layer in a network model include the following:

1. Logical addressing:

The physical addressing implemented by the data link layer handles the addressing problem locally. If a packet passes the network boundary, we need another addressing system to help distinguish the source and destination systems.

The network layer in network model adds a header to the packet coming from the upper layer that, among other things, includes the logical addresses of the sender and receiver.

2. Routing:

When independent network models or links are connected to create internetworks (network of networks) or a large network model, the connecting devices (called routers or switches) route or switch the packets to their final destination. 

One of the functions of the network layer in network model is to provide this mechanism.


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