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The next layer is the third layer of the U.S. reference model, the network layer.

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The network layer provides the means of transferring variable length network packets from a source to

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a destination host via one or more networks.

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In other words, the network layer is responsible for packet forwarding, including routing through

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intermediate routers.

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Within the service learing semantics of the U.S. network architecture, the network layer responds to

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the service requests for the transport layer and issues service requests do the data link layer.

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So here are the functions of the network layer.

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Connection, less communication.

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For example, IP is connection was in that data packet can travel from a center to a recipient without

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the recipient having to send an acknowledgement.

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Connection oriented protocols exist at other higher levels of the U.S. model.

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Host addressing.

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Every host in the network must have a unique address that determines where it is on the Internet, addresses

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are known as IP addresses, right?

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Message forwarding, since many networks are partitioned into sub networks and then connect to other

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networks for a wide area, communications networks use specialized hosts called gateways or routers

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to forward packets between networks.