Method and apparatus for congestion control in a data network
First Claim
1. A method employed to control congestion of data cells in switching nodes of a network wherein one or more virtual circuits for transferring the data cells between endpoints pass through one or more of the switching nodes, said method comprising the steps ofassigning an initial cell buffer to the virtual circuit at each node through which it passes,storing incoming cells for the virtual circuit in its buffer and removing cells from the buffers for forward routing, characterized bydynamically allocating buffer space for the virtual circuit in the nodes in response to signals from at least one of the endpoints requesting an increased or decreased data window in the nodes.
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Abstract
A method of controlling congestion in a virtual circuit packet network. A initial packet buffer is assigned to each virtual circuit at each node into which incoming packets are stored and later removed for forward routing. If a larger buffer is desired for a virtual circuit to service a larger amount of data, then additional buffer space is dynamically allocated selectively to the virtual circuit on demand if each node has sufficient unallocated buffer space to fill the request. In one embodiment, the criterion for dynamic allocation is based on the amount of data buffered at the data source. In alternative embodiments, the criteria for dynamic allocation may be further based on the amount of data buffered at each node for a virtual circuit and the total amount of free buffer space at each node of a virtual circuit. Signaling protocols are disclosed whereby data sources and virtual circuit nodes maintain consistent information describing the buffer allocations at all times.
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Citations
26 Claims
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1. A method employed to control congestion of data cells in switching nodes of a network wherein one or more virtual circuits for transferring the data cells between endpoints pass through one or more of the switching nodes, said method comprising the steps of
assigning an initial cell buffer to the virtual circuit at each node through which it passes, storing incoming cells for the virtual circuit in its buffer and removing cells from the buffers for forward routing, characterized by dynamically allocating buffer space for the virtual circuit in the nodes in response to signals from at least one of the endpoints requesting an increased or decreased data window in the nodes.
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26. A method employed to control congestion of data cells in switching nodes of a network wherein one or more virtual circuits for transferring the data cells between endpoints pass through one or more of the switching nodes, each switching node including a cell buffer for each virtual circuit passing therethrough and said method comprising the steps of:
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for the duration of the virtual circuit, performing steps including determining at an endpoint whether a different-sized cell buffer is needed for the virtual circuit in the virtual circuit'"'"'s switching nodes; if a different-sized cell buffer is needed, providing a first resizing signal from the endpoint to the virtual circuit'"'"'s switching nodes; in each of the virtual circuit'"'"'s nodes, responding to the first resizing signal by indicating the cell buffer size which the node can provide if that is less than the different size; and in each node of the virtual circuit, setting the cell buffer for the virtual circuit to a buffer size which is no greater than the smallest buffer size indicated by any of the switching nodes.
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Specification