Initially presented in 1979 this layered approach was an attempt provide interpretability among computers.
Network managers can assign responsibility within their departments more effectively.
It is easier and less costly to replace any network layer with its equivalent product from another vendor. It is easier to upgrade a network by replacing an individual layer rather than all the software. Physical - Layer 1 provides the electrical, mechanical, functional and procedural characteristics required to move data bits between each end of the communications channel. Describes actual hardware connectors, wire, patch panels and other interconnect devices. PPP Network - Layer 3 describes the way data is directed from node to node, based on prevailing conditions.