Backpressure mechanism for a network device
US6519225B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 14, 1999 |
| Grant date | Feb 11, 2003 |
| Priority date | — |
| Expiry date | May 14, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2012/5683
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are provided for scheduling multicast data in an input-queued network device. According to one aspect of the present invention, the head-of-line blocking problem is avoided for multicast queues. A fabric arbiter receives a transmit request associated with multiple input ports. The transmit request identifies those of the output ports to which pending multicast cells are ready to be transmitted, if any. The fabric arbiter receives a backpressure signal from a backpressuring output port. Then, based upon the backpressure signal the fabric arbiter schedules multicast cells for transmission across the fabric. If the size of a multicast queue exceeds a predetermined threshold, then the fabric arbiter ignores the backpressure signal and causes the head-of-line multicast cell from the multicast queue to be transferred to the backpressuring output port. Otherwise, the fabric arbiter prevents multicast cells from being transferred to the backpressuring output port by masking requests destined for the backpressuring output port thereby removing the backpressuring output port from consideration during multicast scheduling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.