Specifies a Hybrid Ring Control (HRC) protocol which provides a mode of operation in which both packet switched and isochronous data are transmitted within the same special
frame structure, called a cycle. HRC is designed to operate with the existing Media Access Control (MAC), Physical Layer Protocol (PHY), and Physical Medium Dependent (PMD) layers of the FDDI protocol. The HRC is composed of the Hybrid Multiplexer (H-MUX) and the Isochronous Media Access
Control (I-MAC) protocols. The H-MUX integrates packet and isochronous data into cycles which it transmits onto and receives from the medium using the services of the Physical Layer. The IMAC provides separate transmission channels for the transfer of user isochronous data streams. The format, clocking and synchronization of cycles, and the operation and interfaces of the HMUX and I-MAC are defined by this standard. These interfaces include the interface to the FDDI
Station Management (SMT) protocol. The HRC is designed to support various transmission rates, scalable from 100 Mbps in increments of 6,144 Mbps. All transmission rate dependent parameters defined in this document assume a transmission rate of 100 Mbps.
