Traffic shaping system for asynchronous transfer mode networks
First Claim
1. A method for controlling the transmission of cells from a network node, comprising the steps of:
- periodically scanning a table, said table having a number of entries, said number of entries less than a number of virtual circuits connected with said network node, each one of said entries indicating a virtual circuit connected with said network node, each one of said entries corresponding with one of one or more transmit queues, said step of scanning including incrementing a first accumulator and a second accumulator in each one of said table entries, and setting a transmit enable bit in each said table entry having a first accumulator value greater than or equal to a first predetermined value and having a second accumulator value greater than or equal to a second predetermined value;
selecting, responsive to said step of scanning, one of said table entries having said transmit enable bit set; and
transmitting, responsive to said step of selecting, a cell on a virtual circuit indicated by said selected one of said table entries.
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Accused Products
Abstract
A system for controlling the transmission of cells from a network node over multiple Virtual Circuits (VCs) is disclosed. The system performs traffic shaping, as required by connection based systems such as Asynchronous Transfer Mode (ATM), for each VC connected with a network node, so that the Quality of Service (Qos) parameters established when the connection was established are not exceeded. The system includes a process for scheduling the transmission of cells from the network node. The scheduling process periodically scans a table having entries corresponding to virtual circuits connected with the network node. During each scan of the table, the scheduler increments a sustainable rate accumulator field and a peak rate accumulator field of each table entry that corresponds with a virtual circuit that is open, and for which there is a cell ready to be transmitted. The scheduler further determines if the sustainable rate accumulator value is greater than or equal to a predetermined value and whether the peak rate accumulator value is greater than or equal to a predetermined value. If both conditions are true, then a cell may be transmitted on the virtual circuit corresponding with that table entry.
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Citations
21 Claims
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1. A method for controlling the transmission of cells from a network node, comprising the steps of:
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periodically scanning a table, said table having a number of entries, said number of entries less than a number of virtual circuits connected with said network node, each one of said entries indicating a virtual circuit connected with said network node, each one of said entries corresponding with one of one or more transmit queues, said step of scanning including incrementing a first accumulator and a second accumulator in each one of said table entries, and setting a transmit enable bit in each said table entry having a first accumulator value greater than or equal to a first predetermined value and having a second accumulator value greater than or equal to a second predetermined value; selecting, responsive to said step of scanning, one of said table entries having said transmit enable bit set; and transmitting, responsive to said step of selecting, a cell on a virtual circuit indicated by said selected one of said table entries. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for controlling the transmission of cells from a network node, comprising:
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a scheduling table having a number of entries, said number of entries less than a number of virtual circuits connected with said network node each entry indicating a virtual circuit and having a first rate accumulator field, a second rate accumulator field, a first predetermined value and a second predetermined value; means for periodically scanning each said scheduling table entry every time period T, said scanning including incrementing said first rate accumulator field and said second rate accumulator field; means, responsive to said means for scanning, for selecting one of said one or more scheduling table entries having said first rate accumulator field value greater than or equal to said first predetermined value and said second rate accumulator field value greater than or equal to said second predetermined value; means, responsive to said means for selecting, for transmitting a cell on a virtual circuit indicated by said selected one of said one or more scheduling table entries, one or more transmit queues, each transmit queue having zero or more entries, each transmit queue entry indicating a packet to be transmitted and a virtual circuit on which said packet is to be transmitted; each scheduling table entry corresponding with one of said one or more transmit queues; a virtual circuit table having one or more entries, each entry corresponding with a virtual circuit established with said network node, each entry having a first rate accumulator field, a second rate accumulator field, a first predetermined value field and a second predetermined value field; and scheduling table loading means, responsive to a new entry arriving at the head of one of said one or more transmit queues, and further responsive to said scheduling table and said virtual circuit table, for determining a virtual circuit `C` indicated by said entry at the head of said transmit queue, for determining a virtual circuit table entry `E` corresponding with said virtual circuit `C`, and for copying the values of said first rate accumulator field and said second rate accumulator field of virtual circuit table entry `E` into said first rate accumulator field and said second rate accumulator field of a scheduling table entry corresponding with said one of said one or more transmit queues. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification