Editing OSI model (section)

===Layer 3: Network layer===
{{main|Network layer}}
The network layer provides the functional and procedural means of transferring [[network packet|packets]] from one node to another connected in "different networks". A network is a medium to which many nodes can be connected, on which every node has an ''address'' and which permits nodes connected to it to transfer messages to other nodes connected to it by merely providing the content of a message and the address of the destination node and letting the network find the way to deliver the message to the destination node, possibly [[routing]] it through intermediate nodes. If the message is too large to be transmitted from one node to another on the data link layer between those nodes, the network may implement message delivery by splitting the message into several fragments at one node, sending the fragments independently, and reassembling the fragments at another node. It may, but does not need to, report delivery errors.

Message delivery at the network layer is not necessarily guaranteed to be reliable; a network layer protocol may provide reliable message delivery, but it does not need to do so.

A number of layer-management protocols, a function defined in the ''management annex'', ISO 7498/4, belong to the network layer. These include routing protocols, multicast group management, network-layer information and error, and network-layer address assignment. It is the function of the payload that makes these belong to the network layer, not the protocol that carries them.<ref>{{cite ISO standard|csnumber = 14258|title = ISO/IEC 7498-4:1989 – Information technology – Open Systems Interconnection – Basic Reference Model: Management framework|date = 15 November 1989|access-date = 16 November 2024|website = ISO Standards Maintenance Portal|publisher = ISO Central Secretariat.|author = International Organization for Standardization|author-link = International Organization for Standardization}}</ref>