Network Layer

The network layer is the fifth layer above the Open System Interconnection (OSI) model that controls the operation of the subnet.

It manages settings and options related to:-

  • Network addressing,
  • sub-networks, and
  • Inter-working

The network layer is responsible for routing data packages running inside or outside the subnet from source to destination. Two different subnets may have different addresses or may have non-compatible addressing types, or it may be that two different subnets may have different such protocols.

The layer has to deliver packages from source to destination within different subnets, taking into account all the different protocols and different addressing schemes that are not compatible with each other.

In broadcast networks where the routing traffic is heavy, the network layer is either very thin or non-existent. It divides the outgoing data packets into messages and also divides the incoming data packages into smaller messages to reach the upper level.

There is no need for a network layer when two computers are connected or connected by the same link.
It transmits the signal through different channels to the other side and acts as a network controller.

Feature of network layer

Now we will learn about some features of the network layer:-

  • It takes care of the quality of management of network service.
  • Balances traffic load and performs link management functions.
  • Performs security-related tasks.
  • Its main function is to maintain the connection or communication between different protocols and subnets.

Functions of network

  • logical addressing
  • Routing
  • fragmentation and reassembly
  • Path Determination

logical addressing:-

There are two types of network addresses in the Internet world, the first is the data link layer addressing and the second is the logical addressing which is in the network layer.

While in the data link layer the physical address is defined by the MAC address, in the layer of OSI this is done through IP addresses. This IP address is also called a logical address.


Routing is the process of passing data packets from source to destination. The network traveling between source and destination is called routing, which you can understand as:-

  • When we do some search on the Internet, then we enter the URL on the browser, which means that the browser sends your search request to the HTTP server, which in turn sends you some data.
  • Because the server is located outside of your local area network (LAN), your request is routed through the default gateway or by your service provider.
  • This process of sending data requests to the server of the destination is called routing, which is done at the network layer.

fragmentation and reassembly:-

The layer sends a message to the data link layer for successful data transmission. The form in which the network layer receives data is called packets while the data that the data link layer sends is called frames.

The network layer has to fragment and reassemble the data because some data link layer techniques cannot handle large length messages.

For this reason, if the data packet that the network layer wants to send is very large, then the network layer has to break that data into smaller packets and those pieces are sent to the data link layer one by one.

After that when they reach the destination they are reassembled again to put them together in sequence.

Path Determination:-

Thousands of topologies exist on the Internet to connect two different computer systems. Some of them may be private networks through which you may have to spend on sending your data.

In between, some networks can be very busy. But the network layer is smart enough to catch such things within a fraction of a second.

Network layer protocols

Internet Control Manage Protocol(ICMP):–

It is used by network devices such as routers to send all types of fault messages. This fault message may indicate that the data has not reached the destination device or that the requested service is not available.

Internet Group Management Protocol (IGMP):–

used by hosts or adjacent routers in an IPv4 network. This establishes the membership of the multicast group.

Internet Protocol Security (IPsec):–

This secure internet protocol is used for communication, when we send data, then the data reaches the destination only through IP, meanwhile, IPsec is needed to secure the data traveling. is

Routing Information Protocol (RIP):–

It tells the routing metrics by hop count.

Issues with network layer

Here we are mentioning to you what are the issues and what are the issues in the organization layer:

  • decide how the parcel is to be conveyed from the source to the objective. Courses can be founded on static tables that are wired across the organization. They can likewise be dynamic.
  • If there are an excessive number of parcels inside the subnet, they can get in one another’s way. They can make a bottleneck. Controlling such blockage is additionally the obligation of the organization layer itself.
  • Giving nature of administration is its greatest obligation. It implies postponement, time or jitter and so forth
  • Different organizations may have diverse tending to, might be not able to acknowledge bigger bundles, or may have various conventions. The organization layer needs to deal with this so the exchange is progressed nicely.

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