What Layer Is A Router?

What Layer Is A Router? 

Open Systems Interconnection Model also known as the OSI model is a structure that is used to explain how the networking system functions and its components. It describes the way a computer functions within a fixed set of rules and what is needed to establish a connection between different hardware and software. It is defined with 7 different layers. So in which layer of OSI model does a router fall into?

A router falls into the third layer of the OSI model. Which is also known as the Network Layer. This layer has to deliver the data from the source to its destination and back. As we know the router helps to exchange data packets from one host to another host, it falls under the network layer.

In order to understand the layer under which the router falls, it is required to understand the whole OSI model at first. The different layers each have their own functions and all these functions together grant the final output users get from computing. The network layer where routers fall into is a part of the seven layers that build up this whole OSI model. Let’s discuss the OSI model to get a better idea and also see how the router falls under the network layer.

What Is the OSI Model?

The OSI model is a theoretical structure that shows how the different segments contribute to the output. It was created by the International Organization for Standardization (ISO) in 1982 when networking systems were yet to be modernized. The components within have since changed a lot over the years due to digitalization but the model is still in use to explain how the networking system works. 

The Layers of OSI Model

The OSI model is broken into 7 layers which interprets how the networking system works as a whole. All these layers are explained below:

Physical Layer

The physical layer is the first layer of the OSI model. This layer consists of the hardware which is required to send and receive the base data that are passed by the electrical wires and the optical wires and are transmitted across the layers. The data can be radio frequencies, voltage, cabling, and other pin layouts. The hardware in the physical layer is generally the network hubs, modem, adapters, receivers, repeaters, wires, and cables.

Data Link Layer 

The Data Link Layer is the layer where node-to-node data transfer takes place. Here the data are packaged into frames and are sent to the directly connected nodes. If the physical layer has any errors, data link errors also help to correct them. There are two sub-layers of the Data link layer. Media access control (MAC) provides the control of flow over transmission in a network. Logical link control (LAC), identifies errors at the physical layer and corrects them.

Network Layer

The Network Layer is the third layer of the OSI model. In this layer, the data is sent and received between hosts in the form of packet data. The source and the destination of the data are denoted by the IP addresses and based on this, the data is located and transferred. Routers are the heart of the network layer, as this device routes the whole exchange of information between the hosts. The router works as the messenger in the network system.

Transport Layer

The Transport layer is the fourth layer of the OSI model. This layer looks over the data delivery management and checks the error inside the data packets. This layer analyses and regulates the packet’s size, order, and contents and helps to deliver it to the system and the hosts. TCP or the Transmission Control Protocol is the best example of the transport layer.

Session Layer

The fifth layer of the OSI model is the session layer. The session layer looks at the connection between two different computers or systems. It manages the time of connection and looks over the whole process till the termination. It also reconnects and authenticates the connections. This layer can be noticed when we are browning a website, as the whole session we are active in the website falls under this layer.

Presentation Layer

The presentation layer is the sixth layer in the model. It receives the data and decrypts it. It translates the data based on the syntax that is accepted by the application. This layer is the text that the users see after loading a website or any application.

Application Layer

The application layer is the last layer of the OSI model. This layer is where the users interact with the software directly and control the whole process. An example of this layer is the web browser where the users browse different websites and connect to the eternal hosts.

What Layer Is A Router?

As mentioned in the different layers of the OSI model, a router is in the third layer or the Network layer. This layer is the most essential layer for forming a connection with other hosts or users. The modern world where the information is passed from one place to another very swiftly is made possible by the usage of the network layer. And the router is the main driving force of this layer.

A router sends and receives data packets from one network system to another network system. It also dictates the source nat and the destination nat. The router has its IP address which helps it to connect to other routers easily.  This makes network-to-network communications swift and easy. The firewall is also enabled in this layer with the help of a router for a safer connection. The router also controls how different users are going to access the networks.

Using a router, multiple users can connect to the outer network system. The whole network system depends on the router for routing the data packets from the user to its destination, As can be seen, the network layer’s main duty is to receive and send the data packets to its destination, it can be easily understood how the router falls in the third layer of the OSI system. 

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