Method and apparatus for closed loop, out-of-band backpressure mechanism
US7453810B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 27, 2004 |
| Grant date | Nov 18, 2008 |
| Priority date | — |
| Expiry date | Jan 15, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L49/253
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A backpressure mechanism uses a TDM backpressure bus with each port card being assigned time slot. During its time slot, each ingress card/port writes on the bus the number of packets it transmitted to an egress ports during the last data refresh cycle. This information is read by the egress ports and used to compute current depth of the switch fabric output queues. In addition to information received from ingress cards, egress cards keep count of number of packets received from the appropriate switch fabric port and based on it estimate/calculate the current depth of the switch fabric output queue. Congestion states are calculated for all queues by comparing the queue depth with a respective threshold. Each egress card uses these congestion states to generate backpressure signals to ingress cards. Ingress card are using these signals to make decision whether to send or not traffic to destination egress card/port.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.