| 摘要 |
Embodiments of the present invention provide methods and circuits for testing the hybrid capabilities of a station before the station is connected into an FDDI-II hybrid ring. One embodiment tests hybrid mode operation of an FDDI-II non-monitor station by creating a loopback ring, generating cycles for isochronous transmission on the loopback ring, and measuring the progress of the cycles around the loopback ring. The loopback ring created may be internal to a single integrated circuit, internal to a single slave station, or limited to a pair of stations, such as a concentrator and a single attachment station. Another embodiment provides a circuit for use in station on an FDDI-II ring. The circuit includes a loopback circuit which may be configured to create a hybrid ring and a cycle generator for generating cycles on the hybrid ring. The cycle generator includes a small latency adjustment buffer (LAB) and a limited isochronous media access control unit (IMAC) which are incapable of cycle master operation but are sufficient to provide test cycles.
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