For two different systems to communicate with each other and exchange data within a network, it is essential to ensure that they are good addressing. The network layer therefore offers various services and functions for this purpose, as many solutions as it makes available in particular to the transport layer (ie the fourth level).
The main mission of this « network layer » therefore includes the networking that gave it its name, as well as establishing and removing connections. Secure system connections are therefore linked to each other, even if this means going through several networks. If so, the network layer chooses the path and then provides succeeding levels with a transparent connection between the source and the target system.
Other network layer functions include flow control, error analysis and troubleshooting, and physical connection monitoring. Flow control makes it possible, among other things, to buffer the data transferred if the data flow is interrupted at the recipient. To achieve this, the OSI network layer adapts the size of the data packets according to the particularities of the network concerned, to allow a transfer as harmonious as possible.
For packet-oriented services, the network layer also supports the limitation of traffic problems. The network layer works with both connectionless and connection-oriented networks, but it can only work with one type of network at a time.
