GB/T 16678.5-2000 in English

《GB/T 16678.5-2000信息技术 光纤分布式数据接口（FDDI） 第5部分:混合环控制（HRC）》由TC28（全国信息技术标准化技术委员会）归口，TC28SC25（全国信息技术标准化技术委员会信息技术设备互连分会）执行，主管部门为国家标准化管理委员会。
本标准规定了混合环控制(HRC)协议,该协议提供了在同一种特定的称作周期的帧结构中传送包交换数据和等时数据的操作模式。

Scope

This standard specifies the Hybrid Ring Control (HRC) protocol, which provides a mode of operation for transferring packet-switched data and isochronous data in the same specific frame structure called a cycle. HRC is designed to work with the existing Media Access Control (MAC), Physical Layer (PHY) and Physical Media Dependent (PMD) layers in the FDDI protocol. HRC consists of hybrid multiplexer (H-MUX) and isochronous media access control (I-MAC) protocol. The H-MUX incorporates packets and isochronous data into cycles, and it uses the services of the physical layer to send and receive these data to and from the medium. I-MAC provides a separate transmission channel for the transmission of user isochronous data streams. The format, clocking and synchronization of the cycles, as well as the operation and interface of the H-MUX and I-MAC are defined in this standard. These interfaces include interfaces for the FDDI Station Management (SMT) protocol. HRC can be designed to support a variety of transmission rates starting from 100 Mbit/S and 6.144Mbit/s as increments. All transmission rate related parameters defined in this standard are assumed to be a transmission rate of 100Mbit/s. A station consisting of FDDI and HRC entities is called an FDDI-II station. FDDI packs MAC (P-MAC) and HRC components, and their relationship with LLC and a circuit switching multiplexer (CS-MUX) in Figure 1. But the diagram does not imply a certain implementation configuration. The FDDI-II network consists of multiple FDDI-II stations. Interoperability between FDDI stations and FDDI-II stations on the same network is provided by the HRC basic mode that only supports packet transmission. The set of FDDI standards, GB/T 16678, specifies the necessary interfaces, functions and operations to guarantee interoperability between consistent FDDI implementations. This standard specifies the hybrid ring control protocol: HRC. A consistent implementation can employ any design technique without violating interoperability.