Consists largely of hardware.

Provides a solid electrical and mechanical medium to transmit the data.

Transmits bits. Not logical packets, datagrams, or segments.

Also has to deal with mechanical specifications about the makeup of the cables and the design of the connectors.

We’ve mostly already studied what constitutes the physical layer. We don’t need to know more than what we’ve looked at in the Phyical Communication Media chapter.

Have a look at the following slides to understand how data would conceptually travel through the layers.