FDDI standard
The original FDDI standardANSI X3T9.5 was adopted unchanged by the International Standards Organization( ISO) and approved under ISO 9314. The FDDI standard is made up of four parts. In the physical layer, there is the PMD part, Physical Layer Medium Dependent.
The FDDI standard includes the requirements for transmitters and receivers, but also the media-specific part, i.e. the requirements for the optical fiber or other media. Above this is the PHY layer(Physical Layer Protocol), which is also physically oriented. This layer defines the data rate, the 4B5B coding with subsequent coding and decoding according to Non Return to Zero Inverted( NRZ-I), and the FDDI-specific symbol set. The FDDI protocol is handled on the layer above, the MAC layer.
Station Management( SMT) the fourth part of the FDDI standard, handles the commissioning of the FDDI ring, error monitoringand recovery, and the generation of status reports for console management.
The FDDI standard recommends IEEE 802.2( LLC) as an interface to the applications to facilitate transitions to other networks and thus Internetworking.