Hybrid loopback for FDDI-II slave stations
US5465250A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 24, 1993 |
| Grant date | Nov 7, 1995 |
| Priority date | — |
| Expiry date | Jun 24, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L12/433
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.