11. Network layer tasks and protocols

The Network Layer (ISO/OSI model - Layer 3), also known as the Internet Layer, receives fragmented data from the Transport Layer and then performs operations to enable packets to be transmitted across the network. These operations include:

·         Addressing data using IP addresses;

·         Data encapsulation, i.e. the assignment of additional information required by the network layer protocol in use;

·         Routing, i.e. selecting the best route for the parcel;

·         Decapsulation, which removes this additional information when the packet reaches its destination.

The  network communication is governed by certain rules, a communication protocol. Each layer uses its own protocol, independent of the other. The network layer, where they also appear, is no different. The most common communication protocol for this layer is IPv4. It is an open protocol. This means that it does not belong to any one company or business, so it can communicate between devices from different manufacturers. The latest version of such protocol is IPv6, which is also an open protocol.

Currently, many device and software manufacturers are using these protocols in parallel. Maybe in the future IPv6 will completely replace IPv4, but Pv4 is nowadays by far the most widely used network layer protocol.