Each WBC can support a single isochronous channel. Alternatively, on WBC may be subdivided by IMAC into a number of subchannels. These separate subchannels permit simultaneous, independent, isochronous dialogues between different pairs of FDDI-II stations. During normal operation, the activity on an FDDI-II network consists of a sequence of cycles generated by the cycle master. Stations communicate using circuit switching by sharing the use of a dedicated isochronous channel.
Stations communicate using packet switching over the packet data channel.
Initialization - the ring will be configured to initialize in basic mode. Once basic mode is established and operation, one or more stations may attempt to move the network to hybrid mode by issuing a cycle. Programming template maintenance - the cycle master maintains the programming template. The allocation of capacity between packet and circuit transmission may be modified dynamically by means of SMT requests to the cycle master. FDDI can transport both asynchronous and synchronous types of frames.