Method and apparatus for scheduling cells for use in a static priority scheduler
First Claim
1. A method for scheduling a plurality of cells of N number of prioritized queues in a node of an ATM network, N being a positive integer, wherein each prioritized queue has a static priority different from priorities of other queues, the method comprising the steps of:
- (a) in response to a cell having a jth static priority, calculating a holding time after which the cell will be eligible for transmission, wherein the static prioritized number j is a positive integer less than or equal to N and a smaller static prioritized number has a higher priority;
(b) holding the cell for the holding time so that the cell becomes eligible for transmission;
(c) generating an empty flag EFj of a value either `0` or `1` on a time slot basis, wherein the empty flag EFj of a value `0` represents that there exists an eligible cell for transmission in a corresponding jth prioritized queue while that of a value `1` indicates that there is none eligible;
(d) switching a jth prioritized queue to a higher prioritized switch in a jth prioritized switch based on the empty flag EFj, wherein the jth prioritized switch has two input terminals, a jth one and a lower one, which are connected to the jth prioritized queue and a lower prioritized switch, respectively, and an output terminal, which is connected to the higher prioritized switch; and
the output terminal of a first prioritized switch is attached to a transmitter for transmission and the lower input terminal of an Nth prioritized switch is attached to a non real-time queue which has non-prioritized cells; and
(e) transmitting the eligible cell attached to the transmitter to a destined next node on a time slot basis.
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Abstract
A method for scheduling a plurality of cells of N number of prioritized queues in a node of an ATM network is provided, wherein each prioritized queue has a static priority different from priorities of other queues. In response to receipt of a cell having a jth static priority, the cell is held for a holding time so that the cell turns to be an eligible cell for transmission. Meanwhile, an empty flag EFj `0` or `1` is generated on a time slot basis, wherein the empty flag EFj `0` or `1` represents whether or not there exists the eligible cell for transmission in the corresponding jth prioritized queue; and the jth prioritized queue is switched to a higher prioritized switch in a jth prioritized switch based on the empty flag EFj, wherein the jth prioritized switch has a jth and a lower input terminals, which are connected to the jth prioritized queue and the lower prioritized switch, respectively, and an output terminal, which is connected to the higher prioritized switch.
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Citations
7 Claims
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1. A method for scheduling a plurality of cells of N number of prioritized queues in a node of an ATM network, N being a positive integer, wherein each prioritized queue has a static priority different from priorities of other queues, the method comprising the steps of:
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(a) in response to a cell having a jth static priority, calculating a holding time after which the cell will be eligible for transmission, wherein the static prioritized number j is a positive integer less than or equal to N and a smaller static prioritized number has a higher priority; (b) holding the cell for the holding time so that the cell becomes eligible for transmission; (c) generating an empty flag EFj of a value either `0` or `1` on a time slot basis, wherein the empty flag EFj of a value `0` represents that there exists an eligible cell for transmission in a corresponding jth prioritized queue while that of a value `1` indicates that there is none eligible; (d) switching a jth prioritized queue to a higher prioritized switch in a jth prioritized switch based on the empty flag EFj, wherein the jth prioritized switch has two input terminals, a jth one and a lower one, which are connected to the jth prioritized queue and a lower prioritized switch, respectively, and an output terminal, which is connected to the higher prioritized switch; and
the output terminal of a first prioritized switch is attached to a transmitter for transmission and the lower input terminal of an Nth prioritized switch is attached to a non real-time queue which has non-prioritized cells; and(e) transmitting the eligible cell attached to the transmitter to a destined next node on a time slot basis. - View Dependent Claims (2, 3)
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4. An apparatus for scheduling a plurality of cells of N number of prioritized queues in ATM network, N being a positive integer, wherein each prioritized queue has a static priority different from priorities of other queues, the apparatus comprises:
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means, in response to a cell having a jth static priority, for calculating a holding time after which the cell will be eligible for transmission, wherein the static prioritized number j is a positive integer less than or equal to N and a smaller static prioritized number has a higher priority; means for holding the cell for the holding time so that the cell becomes eligible for transmission; means for signaling time slots, wherein at most one eligible cell per time slot is transmitted; means for generating an empty flag EFj of a value either `0` or `1` on a time slot basis, wherein the empty flag EFj of a value `0` represents that there exists an eligible cell for transmission in a corresponding jth prioritized queue while that of a value `1` indicates that there is none eligible; N prioritized switches, jth prioritized switch for switching a jth prioritized queue to an adjacent higher prioritized switch based on the empty flag EFj, j having values from 1 to N, wherein the jth prioritized switch has two input terminals, a jth one and a lower one, which are connected to the jth prioritized queue and a lower prioritized switch, respectively, and an output terminal, which is connected to the higher prioritized switch; and
the output terminal of a first prioritized switch is attached to a transmitter for transmission and the lower input terminal of an Nth prioritized switch is attached to a non real-time queue which has non-prioritized cells; andmeans for transmitting the eligible cell attached to the transmitter to a destined next node on a time slot basis. - View Dependent Claims (5, 6, 7)
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Specification