Method and apparatus for selectively discarding packets
First Claim
1. A method for discarding packets, the method comprising the steps of:
- storing a number of packets for transmission in a buffer;
detecting when the number of stored packets reaches a predefined level; and
responsive to the detecting step, retrieving a channel identifier from a packet;
checking if prior packets associated with the channel identifier were discarded over a previous time interval;
if at least one of the prior packets was previously discarded, forwarding the packet for transmission; and
discarding the packet otherwise.
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Accused Products
Abstract
In a packet voice system, discarding of a packet is performed as a function of previously discarded packets. In one embodiment, a packet voice system includes an ATM Adaptation Layer Type 2 (AAL2) and Service Specific Convergence Sublayer (SSCS) System. In this system, a transmission buffer stores AAL2 voice packets for transmission, each AAL2 voice packet comprising a sequence number, the values of which range from 0 to n−1, and a source identifier, k. When traffic congestion is detected, the transmitter portion of the SSCS System selectively discards one packet from a source k at the output of the transmission buffer if no packet from source k was dropped in either the last n−1 packets or over a predefined prior interval of time. Another embodiment of the invention discards packets at the input of the transmission buffer.
160 Citations
43 Claims
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1. A method for discarding packets, the method comprising the steps of:
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storing a number of packets for transmission in a buffer;
detecting when the number of stored packets reaches a predefined level; and
responsive to the detecting step, retrieving a channel identifier from a packet;
checking if prior packets associated with the channel identifier were discarded over a previous time interval;
if at least one of the prior packets was previously discarded, forwarding the packet for transmission; and
discarding the packet otherwise. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for discarding packets, the method comprising the steps of:
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(a) retrieving a channel identifier from a packet stored in a buffer;
(b) retrieving a fill value of the buffer;
(c) if the fill value of the buffer is less than a predefined level, forwarding the packet for transmission;
(d) if the fill value is not less than a predefined level, checking if prior packets associated with the channel identifier were previously discarded;
if at least one of the prior packets was previously discarded, forwarding the packet for transmission; and
discarding the packet otherwise. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for discarding packets, the method comprising the steps of:
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(a) retrieving a channel identifier from a packet;
(b) retrieving a fill value of a buffer;
(c) if the fill value of the buffer is less than a predefined level, storing the packet in the buffer;
(d) if the fill value is not less than a predefined level, checking if prior packets associated with the channel identifier were previously discarded; and
if at least one of the prior packets was previously discarded, storing the packet in the buffer;
discarding the packet otherwise. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A method for discarding packets, the method comprising the steps of:
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(a) retrieving a channel identifier from a packet;
(b) retrieving a fill value of a buffer;
(c) if the fill value of the buffer is less than a predefined level, storing the packet in the buffer;
(d) if the fill value is not less than a predefined level, checking if prior packets associated with the channel identifier were previously discarded;
(i) if at least one of the prior packets was previously discarded, checking the buffer for any stored packets that have not had a prior packet discarded;
(ii) if a stored packet is found that has not had a prior packet discarded, discarding this stored packet;
adding the packet to the buffer; and
(iii) if a stored packet is not found that has not had a prior packet discarded;
discarding the packet. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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27. Apparatus for discarding packets, the apparatus comprising:
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a buffer for storing a number of packets for transmission; and
a processor for detecting when the number of stored packets reaches a predefined level, and, responsive to the detection, (a) retrieving a channel identifier from a packet, (b) checking if prior packets associated with the channel identifier were previously discarded, and (c) if at least one of the prior packets was previously discarded, forwarding the packet for transmission, and discarding the packet otherwise. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. Apparatus for discarding packets, the apparatus comprising:
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a first processing element for forming packets, each packet having a channel identifier;
a buffer for storing the formed packets; and
a second processor for (a) detecting when the number of stored packets reaches a predefined level as a precondition to discarding ones of the formed packets, (b) retrieving a channel identifier from ones of the formed packets, (c) checking if prior packets associated with the channel identifier were previously discarded, and (d) if at least one of the prior packets was previously discarded, forwarding the packet for transmission, and discarding the packet otherwise. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification