Switching device for controlling data packet flow
First Claim
1. A method for controlling a data packet flow through a switching device comprising a first number of first stage switch modules, a second number of second stage switch modules and a third number of third stage switch modules, each of the switch modules, having a number of data inputs a number of data outputs and a data packet buffer the data outputs of the first stage switch modules being connected to the data inputs of the second stage switch modules and the data outputs of the second stage switch modules to the data inputs of the third stage switch modules;
- wherein a data packet received at a data input of one of the first stage switch modules is forwarded to a specific data output of one of the third stage switch modules;
the method comprising the steps of;
storing credit information associated to each of the second stage switch modules indicating a number of free data packet buffer locations in the respective second stage switch module;
selecting one of the second stage switch modules in dependence on the credit information;
forwarding the received data packet from the first stage switch module to the selected second stage switch module;
forwarding the received data packet from the selected second stage switch module to the respective third stage switch module, from which the received data packet is to be sent;
after sending the data packet from the respective third stage switch module, delivering a credit information about the freed data packet buffer location from the third stage switch module to the second stage switch module, wherein the respective second stage switch module is selected according to a credit return strategy.
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Abstract
Methods for controlling a data packet flow through a switch having first, second and third stage switch modules. Each switch module has a number of data inputs, a number of data outputs, and a data packet buffer. The data outputs of the first stage switch modules are connected to data inputs of the second stage switch modules, and data outputs of the second stage switch modules are connected to the data inputs of the third stage switch modules. A data packet received at one of the first stage switch modules is forwarded to a specific data output of one of the third stage switch modules. A method for controlling a data packet flow comprises: A storing credit information associated to each of the second stage switch modules indicating a number of free data packet buffer locations in the respective second stage switch module; selecting one of the second stage switch modules in dependence on the credit information; forwarding the received data packet from the first stage switch module to the selected second stage switch module; forwarding the received data packet from the selected second stage switch module to the respective third stage switch module, from which the received data packet is to be sent; after sending the data packet from the respective third stage switch module, delivering a credit information about the freed data packet buffer location from the third stage switch module to the second stage switch module, wherein the respective second stage switch module is chosen by a credit return strategy.
39 Citations
13 Claims
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1. A method for controlling a data packet flow through a switching device comprising a first number of first stage switch modules, a second number of second stage switch modules and a third number of third stage switch modules, each of the switch modules, having a number of data inputs a number of data outputs and a data packet buffer the data outputs of the first stage switch modules being connected to the data inputs of the second stage switch modules and the data outputs of the second stage switch modules to the data inputs of the third stage switch modules;
- wherein a data packet received at a data input of one of the first stage switch modules is forwarded to a specific data output of one of the third stage switch modules;
the method comprising the steps of;
storing credit information associated to each of the second stage switch modules indicating a number of free data packet buffer locations in the respective second stage switch module;
selecting one of the second stage switch modules in dependence on the credit information;
forwarding the received data packet from the first stage switch module to the selected second stage switch module;
forwarding the received data packet from the selected second stage switch module to the respective third stage switch module, from which the received data packet is to be sent;
after sending the data packet from the respective third stage switch module, delivering a credit information about the freed data packet buffer location from the third stage switch module to the second stage switch module, wherein the respective second stage switch module is selected according to a credit return strategy. - View Dependent Claims (2, 3, 4, 5, 6, 12, 13)
- wherein a data packet received at a data input of one of the first stage switch modules is forwarded to a specific data output of one of the third stage switch modules;
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7. A first stage switch module of a three or more stage switching device comprising:
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a number of data inputs;
a number of data outputs to be connected to second stage switch modules;
a data packet buffer to receive and to store externally received data packets;
a credit memory to store a first credit information for each of the second stage switch modules, wherein the credit memory has an input to receive an information about a freed data packet buffer location in one of the second stage switch modules;
a packet scheduling means to select the data output, on which a received data packet is to be sent, depending on the stored credit information of each of the second stage switch modules connected to the data outputs;
a credit insertion means to insert one or more credits in a data packet to be sent to a chosen second stage switch module associated with a respective data output to return the one or more credits according to a second credit information to the chosen second stage switch module wherein the second stage switch module is chosen by the packet scheduling means according to an appropriate credit return strategy. - View Dependent Claims (9, 10, 11)
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8. A third stage switch module comprising:
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a number of data inputs to be connected to second stage switch modules;
a number of data outputs;
a data packet buffer to receive and to store data packets from the second stage switch modules;
a credit extraction means to extract first credit information sent by the second stage switch modules and to provide the respective credit information used for a path selecting function which is operable to select a path for a data packet between a first stage switch module and a second stage switch module;
a packet scheduling means to send data packets to the respective data output in a given order and according to their destination and to return a credit information to one of the second stage switch modules.
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Specification