Method and apparatus for request/grant priority scheduling
First Claim
1. A method for scheduling traffic in a communications node having a plurality of line cards coupled to a switch fabric, the method comprising the steps of:
- a) sending, to the switch fabric by a first line card of the line cards, a first request for transmitting a first unit of the traffic of a first priority to the switch fabric, the first request indicating a first output port for which the first unit of the traffic is destined; and
b) using, by the first line card, a first grant received from the switch fabric permitting transmission of the first unit of the traffic to the switch fabric and issued in response to a second request made for a second unit of the traffic having a second priority lower than the first priority and being destined to the first output port, for scheduling transmission of the first unit of the traffic to the switch fabric.
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Abstract
In accordance with at least one embodiment of the present invention, a method and apparatus for scheduling traffic in a communications node is provided. Line cards request communication opportunities from a switch fabric. The switch fabric issues grants for such communication opportunities in response to specific requests. By dynamically adjusting usage of such communication opportunities corresponding to such grants among requests of differing priorities and/or latency criteria, embodiments of the present invention are able to provide increased capacity utilization of switching fabric bandwidth while maximizing adherence to priority requirements and/or latency criteria.
15 Citations
14 Claims
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1. A method for scheduling traffic in a communications node having a plurality of line cards coupled to a switch fabric, the method comprising the steps of:
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a) sending, to the switch fabric by a first line card of the line cards, a first request for transmitting a first unit of the traffic of a first priority to the switch fabric, the first request indicating a first output port for which the first unit of the traffic is destined; and b) using, by the first line card, a first grant received from the switch fabric permitting transmission of the first unit of the traffic to the switch fabric and issued in response to a second request made for a second unit of the traffic having a second priority lower than the first priority and being destined to the first output port, for scheduling transmission of the first unit of the traffic to the switch fabric. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for scheduling traffic in a communications node having a plurality of line cards coupled to a switch fabric comprising:
a first line card of the plurality of line cards, the first line card configured to send requests for transmitting units of the traffic of specified priorities to the switch fabric and to receive grants permitting transmission of the units of the traffic to switch fabric, the first line card further configured to utilize a first grant of the grants corresponding to a first request of the requests, wherein the first request is of a lower priority than a second request of the requests, for transmitting a first unit of the traffic corresponding to the second request to the switch fabric. - View Dependent Claims (8, 9, 10)
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11. Apparatus for scheduling traffic in a communications node having a plurality of line cards coupled to a switch fabric comprising:
a first line card of the plurality of line cards, the first line card further comprising; a first means configured to send requests for transmitting units of the traffic of specified priorities to the switch fabric and to receive grants permitting transmission of the units of the traffic to switch fabric; and a second means configured to utilize a first grant of the grants corresponding to a first request of the requests, wherein the first request is of a lower priority than a second request of the requests, for transmitting a first unit of the traffic corresponding to the second request to the switch fabric. - View Dependent Claims (12, 13, 14)
Specification