The Network Layer: 5 Important Functions of Network Layer

Today we are going to talk about the Network layer of the OSI model & important functions of network layer. The network layer of the OSI model defines how communication occurs across different networks and determines how data is transported from one network to another.

The network layer is responsible for delivering the data packets from the source to the destination. Whereas a data link layer is helpful in delivering data packets from node to node in the same network.

The network layer is the third layer in the OSI model. It receives data from the transport layer and delivers it to the data link layer. In this article, we will know what is the functions of the network layer and how it works together with the data link layer and transport layer.

5 important functions of Network layer

The important functions of Network Layer is to send data packets from one host to another (from source to destination). It is needed to connect hosts from one network to another. Different functions are used to send data to the network layer.

Host-to-Host Delivery

We also call this host-to-host delivery as machine-to-machine delivery. In the diagram given below, a machine in one network transfers data to a machine in another network. This data transfer happens only through a medium. Therefore, a router is used between them to connect different networks.

functions of network layer

If a machine on network A needs to share data with a machine on network B, it cannot communicate directly. So it follows a path. When a network host sends data, it sends that data to Router-1 connected to that network. After that, Router-1 finds the shortest path and then sends the data to another Router-2. Router-2 again finds the shortest path and transmits that data to the destination.

This type of node-to-node delivery of data is due to the Datalink layer. But in the network layer, the delivery of data packets takes place from source to destination. This transmission of data packets happens with the help of a logical address. it is also called an IP Address.

Logical Address

The logical address is also called the IP address. Source-to-destination delivery is done with the help of a logical address. A logical address is made up of two things. One is the Network id and the other is the Host id.

This IP address is used in the network layer. When a data packet is sent from the source to the destination, only then the IP address of the source and the IP address of the destination is added to that packet. So that packet can reach its destination in the right way.

The IP address is 32 bits. The first 8 bits are called the network ID and the remaining 24 bits are called the host ID. Earlier the use of the internet was very less and there were not many companies which needed more hosts. But today’s internet users have increased and all companies are using the internet.

In view of this increasing use of the Internet, the classful addressing concept was introduced. In this, the IP address was divided into 5 parts. Like


All these IP addresses have been told in detail in the previous article. You can read it by clicking on the link given below.


Routing means how the router delivers a data packet safely to its destination. There is an important functions of network layer which is called forwarding. This means that sending a packet to the actual destination by putting it in the right path is called forwarding.

Router provisioning is very high in the network layer. Because the router itself decides which destination the data has to go to and its shortest path. We also use switches in the network layer. When there are many nodes in the network, many wires are needed to connect them all to each other. But due to the use of switches, the wire usage gets reduced.

A router is connected to many networks. When a signal comes to the router from another network. The router checks that signal internally, then decide and finds the shortest path and sends it to the actual destination. All this work of the router can be done with the help of a routing table.

Also, Read

There must be a doubt in your mind that what is the routing table. So in a network, any work is done like sending data packets, receiving, which node is sending what? Which is the shortest path to send data, all this information is stored in the routing table.

There are two types of routing tables. One is the static routing table and the other is the dynamic routing table. In a static rotating table, the user has to insert the data into the table manually. This is handled by the network administrator.

But when the network becomes large or has to manage the routing tables of many networks, then dynamic routing tables are used. With the help of a dynamic routing table, the router automatically communicates with the node and sends the data to the destination. Dynamic routing tables can be work automatically with the help of different types of routing protocols.


Fragmentation technology is used in the network layer. Like a node sends a data packet from a network. After that, the same data goes to the connecting router of that network. That router checks the data packet and sends it to another router on the path of the destination. But the data that is confirmed is not the capacity of that router. This means that the data is more than the storage capacity of the router.

Therefore, the previous router splits that data into multiple fragments and sends as much data as the other router has the capacity. After that Router 2 finds the shortest route to send the data and makes it smooth to the destination. In this way, fragmentation is used in the network layer.

Error Reporting

In the network layer of the OSI model, data transmission takes place through IP addresses. Very little error is produced in this transmission. if any error produces during the transmission, then ICMP technology is used to find out this error. The full form of ICMP is Internet Control Message Protocol.


Today we have discussed the important functions of network layer of the OSI model. I hope all of you have understood this topic clearly. If you do not understand in any place or need improvement in someplace, then you tell us in the comment box. I will try my best to solve your problem.

!!Thanks for reading this article!!

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