Network Layer

Network layer is also known as layer 3 because it is third of the seven-layer OSI model of computer networking. The duty of the this particular layer becomes to route pockets delivery including to route through intermediate routers, where the data link layer is responsible for media access control, flow control and error checking. This layer offers the practical and procedural means of transferring variable length data sequences from a source to a destination host through a few networks while maintaining the quality of service functions.

The purpose of the Network Layer

The main function of the network layer is connection model, host addressing and massage forwarding. In the connection model or the connectionless communication a frame can travel from a sender to a recipient without the recipient having to send recognition. The other connection-oriented protocols subsist at other higher levels of that model. In host addressing, all the host in the network requires to have a unique decides where it is located. This address will usually be allotted from a hierarchical system. This is because on the internet addresses are called as internet protocol addresses.

Messages Sent to Various Uses

Several networks are divided into sub-networks and connected to the networks for wide range of communications, networks bring into play specialized hosts known as gateways or routers to forward packets between networks. In mobile applications these are of great interest because a user moves to different locations and so messages should reach him wherever he goes. Inside the service layering semantics of the OSI network architecture the network layer reacts to check requests from the transport layer and issues check requests to the data link layer.

The Connection with TCP/IP Model

The network layer is well related to the TCP/IP model. And this model has a layer known as internet layer which is situated above the link layer. In texts and written materials the internet layer is equated with OSI’s network layer. But it can be misleading as the permitted characteristics of protocols placed here into these layers are different in the two models. The internet layer of TCP/IP is actually a subset of functionality of the network layer. This only explains one kind of network build up, the internet.

In common, straight or strict comparisons of different models must be avoided, for layering in TCP/IP is not a fundamental criterion and the internet engineering task force considers it to be harmful.

Questions:

• What is network layer?
• What are the uses of network layer?