Layer 1 – Physical

The Physical Layer has many functions:


 * Defines the electrical and physical specifications of the data connection including
 * layout of pins
 * voltages
 * impedance of line
 * cabling
 * various network devices that facilitate moving the signal along
 * Defines the protocol used to establish and terminate a connection between two devices (nodes)
 * May define flow control
 * Defines a protocol for moving the data from a digital device onto the network