Network layer

In the seven-layer OSI model of computer networking, the network layer is layer 3, the layer responsible for packet forwarding, including routing through intermediate routers. It transfers variable-length packets from a source host to a destination host across one or more networks, answering service requests from the transport layer above and issuing service requests to the data link layer below. Its functions include connectionless communication, hierarchical host addressing, which on the Internet takes the form of IP addresses, and the forwarding of packets between networks by gateways or routers. The Internet layer of the TCP/IP model is often equated with it, but that comparison is misleading, because the Internet layer covers only a subset of the functionality of the OSI network layer.