This video is the last of the series about the physical layer of the ISO OSI model. It uses RS-232-C to remind us of functional, mechanical, electrical and procedural specifications when interacting on the physical layer. This approach is recommended for thinking about more recent media interfaces. The video finally considers the use of undersea optical fibre cables to achieve global communication.

The video is part of a lecture series made at home to continue online education during COVID-19 lockdown.