Method and apparatus for enhanced partial packet discard
AssigneeNortel Networks Limited
InventorsNorman Allan Lyon, Gregory Lloyd King, Ra'ed Yousif Awdeh
Life of this patent
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Abstract
In an enhanced partial packet discard (PPD) methodology, if an end-of-packet cell is discarded for non-PPD reasons, all non-end-of-packet cells of the immediately following packet are discarded. When an end-of-packet cell may validly be discarded, a switch faced with an end-of-packet cell may discard that cell if the last cell admitted to the buffer was an end-of-packet cell. To reduce the likelihood of having to drop end-of-packet cells, a buffer is configured to include a partial packet discard threshold such that the buffer space between that threshold and the end of the buffer is reserved for use by end-of-packet cells.
Claims21
A method for controlling congestion across a link in a network, the network including at least one switch having at least one buffer for receiving cells transmitted over the network in packets, each packet including at least an end-of-packet cell, the method comprising the steps, performed by the switch, of:
- determining whether the end-of-packet cell of a first packet had been discarded as a result of congestion;
- and discarding all non-end-of-packet cells of a second packet if the end-of-packet cell of the first packet had been discarded as a result of congestion.
A method, for use in controlling congestion across a link in a network including at least one switch having at least one buffer for receiving cells transmitted over the network in packets, each packet including at least an end-of-packet cell, the method comprising the steps, performed by the switch, of:
- discarding a non-end-of-packet cell of a first packet as a result of congestion;
- discarding any remaining non-end-of-packet cells of the first packet;
- discarding the end-of-packet cell of the first packet as a result of congestion;
- and
- discarding all non-end-of-packet cells of a second packet transmitted immediately following the first packet.
An apparatus for controlling congestion across a link in a network, the network including at least one switch having at least one buffer for receiving cells transmitted over the network in packets, each packet including at least an end-of-packet cell, the apparatus comprising:
- means for determining whether the end-of-packet cell of a first packet had been discarded as a result of congestion;
- and means for discarding all non-end-of-packet cells of a second packet if the end-of-packet cell of the first packet had been discarded as a result of congestion.
An apparatus, for use in controlling congestion across a link in a network including at least one switch having at least one buffer for receiving cells transmitted over the network in packets, each packet including at least an end-of-packet cell, the apparatus comprising:
- means for discarding a non-end-of-packet cell of a first packet as a result of congestion;
- means for discarding any remaining non-end-of-packet cells of the first packet;
- means for discarding the end-of-packet cell of the first packet as a result of congestion;
- and
- means for discarding all non-end-of-packet cells of a second packet transmitted immediately following the first packet.
A method for controlling congestion across a link in a network, the network including at least one switch having at least one buffer used by a connection for receiving cells transmitted over the network in packets, each packet including at least an end-of-packet cell, the method comprising the steps of:
- admitting cells into the buffer;
- discarding at least one non-end-of-packet cell of a packet as a result of congestion;
- discarding all non-end-of-packet cells of the packet not yet admitted into the buffer for the connection;
- determining whether the last cell admitted to the buffer for the connection is an end-of-packet cell;
- and
- discarding the end-of-packet cell of the packet if the last cell admitted to the buffer for the connection is an end-of-packet cell.
An apparatus for controlling congestion across a link in a network, the network including at least one switch having at least one buffer used by a connection for receiving cells transmitted over the network in packets, each packet including at least an end-of-packet cell, the apparatus comprising:
- means for discarding at least one non-end-of-packet cell of a packet as a result of congestion;
- means for discarding all remaining non-end-of-packet cells of the packet not yet admitted into the buffer for the connection;
- means for determining whether the last cell admitted to the buffer for the connection is an end-of-packet cell;
- and
- means for discarding the end-of-packet cell of the packet if the last cell admitted to the buffer for the connection is an end-of-packet cell.
A method for controlling congestion across a link in a network, the network including at least one switch having at least one buffer for receiving cells transmitted over the network in packets, each packet including at least an end-of-packet cell, the method comprising the steps of:
- establishing a threshold within the buffer and a buffer end;
- and
- admitting cells into the buffer, the buffer space between the threshold and the end of the buffer reserved for queuing end-of-packet cells so as to reduce the likelihood of having to discard end-of-packet cells.
An apparatus for controlling congestion across a link in a network, the network including at least one switch having at least one buffer for receiving cells transmitted over the network in packets, each packet including at least an end-of-packet cell, the apparatus comprising:
- a buffer configured to include a threshold and an end, the buffer space between the threshold and the end of the buffer reserved for queuing end-of-packet cells so as to reduce the likelihood of having to discard end-of-packet cells.
A communications network comprising:
- a plurality of nodes sending and receiving packets of cells, each packet including at least an end-of-packet cell;
- and
- a switch interconnecting the nodes, the switch including
- means for discarding cells as a result of congestion,
- means for determining whether an end-of-packet cell of a first packet had been discarded as a result of congestion, and
- means for discarding all non-end-of-packet cells of a second packet if the end-of-packet cell of the first packet had been discarded as a result of congestion.
A communications network comprising:
- a plurality of nodes sending and receiving packets of cells, each packet including at least an end-of-packet cell;
- and
- a switch interconnecting the nodes, the switch including
- a buffer used by a connection,
- means for discarding at least one non-end-of-packet cell of a packet as a result of congestion,
- means for discarding all non-end-of-packet cells of the packet not yet admitted into the buffer for the connection,
- means for determining whether the last cell admitted to the buffer for the connection is an end-of-packet cell, and
- means for discarding the end-of-packet cell of the packet if the last cell admitted to the buffer for the connection is an end-of-packet cell.
A communications network comprising:
- a plurality of nodes sending and receiving packets of cells, each packet including at least an end-of-packet cell;
- a switch interconnecting the nodes, the switch including a buffer, the buffer configured to include a threshold and an end, the buffer space between the threshold and the end of the buffer reserved for queuing end-of-packet cells so as to reduce the likelihood of having to discard end-of-packet cells.
Dependencies are inferred from the claim text.