It is typically measured at a reference point below the network layer and above the physical layer.

The protocol (network layer) address is that of the destination host.

Its capabilities and structure are those typically associated to such network layers, including routing.

The security architecture is distributed among the network layers as follows:

Information frames, or I-frames, transport user data from the network layer.

Windows 3.1 did not even have a network layer installed by default.

But as no acknowledgement mechanism is present in the network layer, the client does not know whether the data has reached the destination successfully.

Hence some remedial measures should be taken by the network layer to avoid these kind of situations.

These kinds of functionality must then be provided by higher network layers.

Class 0 contains no error recovery, and was designed for use on network layers that provide error-free connections.