Efforts to standardize local networks started in 1979 under the direction of the IEEE (Institute of Electrical and Electronics Engineers). The goal of standardization was to adapt layer 1 and 2 of the OSI (Open System Interconnection) model to the specificities of local and metropolitan networks. In February 1980, the working group was named 802 (80 for the year and 2 for the month).
The goal of the IEEE 802 committee is to develop a standard enabling the transmission of information frames between two computer systems of current design, through a medium shared between these systems, whatever their architecture.
To adapt the OSI model to local networks, we must take into account application specificities that cause the traffic to have different characteristics:
— file transfers: the data rate must be high and error rate very low; propagation delays can be high;
— office applications: data rate can punctually be high, error rate must be low, and propagation delays must be low;
— command/control process: data rates are relatively low but transmission times must be bound, error rate must be low;
— images/voice transmission: data rates are relatively high, transmission time must be as low as possible. On the other hand, error rate can be higher.
The ISO reference model is built from a mesh architecture, and equipment is connected by point-to-point links. In local networks, the way to ...