Method for handling redundant switching planes in packet switches and a packet switch for carrying out the method
First Claim
1. In a packet switch comprising an input side including an input unit for receiving a sequence of data packets arriving at the switch;
- an output side including an output unit for forwarding the sequence of data packets from the switch; and
at least two identical switching planes, each having an input coupled to receive the sequence of data packets from the input unit and coupled to provide the sequence of data packets to the output unit, a method for forwarding, from the output unit, the sequence of data packets, comprising the steps of;
at the input unit receiving the sequence of data packets and supplying the sequence of data packets to each of the switching planes;
at each of the switching planes, supplying the sequence of data packets to the output unit; and
at the output unit, for each arriving data packet in the sequence of data packets, selecting a preferred switching plane from the at least two identical switching planes, and receiving from the preferred switching plane a preferred data packet to be forwarded from the output unit, wherein the step of selecting comprises;
generating, for each of the switching planes, a corresponding quality value based on earlier arriving data packets that have been supplied to the output unit, the quality value indicating to what extent the switching plane has transmitted without error, from the input unit to the output unit, the earlier arriving data packets;
using the quality values to select the preferred switching plane.
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Accused Products
Abstract
A switch for the transfer of data packets comprises in the conventional way input ports and output ports and parallel switching planes, which are identical to each other. The switch establishes connections between input ports and output ports through the parallel switching planes. In each output port there is for each switching plane and each established connection a buffer accommodating at least one data packet. In the output port there is in addition a logical selection device for selecting data packets from the switch and from the different planes in such a way, that a data packet stream, which is as correct as possible, is obtained from the output port, and it selects in the first place data packets from a switching plane, which is the preferred plane at each instant. The selection device comprises a quality determining unit, which at each occasion determines the preferred plane by means of quality values for each plane. These quality values are determined by means of an evaluation of earlier data packets, which have arrived to the output port.
89 Citations
41 Claims
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1. In a packet switch comprising an input side including an input unit for receiving a sequence of data packets arriving at the switch;
- an output side including an output unit for forwarding the sequence of data packets from the switch; and
at least two identical switching planes, each having an input coupled to receive the sequence of data packets from the input unit and coupled to provide the sequence of data packets to the output unit, a method for forwarding, from the output unit, the sequence of data packets, comprising the steps of;at the input unit receiving the sequence of data packets and supplying the sequence of data packets to each of the switching planes; at each of the switching planes, supplying the sequence of data packets to the output unit; and at the output unit, for each arriving data packet in the sequence of data packets, selecting a preferred switching plane from the at least two identical switching planes, and receiving from the preferred switching plane a preferred data packet to be forwarded from the output unit, wherein the step of selecting comprises; generating, for each of the switching planes, a corresponding quality value based on earlier arriving data packets that have been supplied to the output unit, the quality value indicating to what extent the switching plane has transmitted without error, from the input unit to the output unit, the earlier arriving data packets; using the quality values to select the preferred switching plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- an output side including an output unit for forwarding the sequence of data packets from the switch; and
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21. A data packet switch for transferring data packets, comprising:
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an input side including at least one input unit for receiving data packets arriving at the switch; an output side having at least one output unit; at least two identical switching planes, each coupled to the input side and to the output side; and connection establishing means for establishing, through the switching planes, a connection between a first input unit of the at least one input unit and a first output unit of the at least one output unit, whereby a data packet arriving at the first input unit will be transferred through each of the switching planes to the first output unit, wherein the first output unit includes; forwarding means for forwarding data packets from the first output unit; a plurality of buffers, each associated With a corresponding one of the switching planes, and each for storing at least one data packet received from the corresponding one of the switching planes; a pointer for indicating a currently preferred one of the switching planes; a selection device, coupled to the pointer, for selecting the preferred switching plane as a source of data packets to be forwarded by the forwarding means; a quality determining unit, coupled to each of the switching planes, for repeatedly determining, for each switching plane, a corresponding quality value based on earlier arriving data packets that were received on that switching plane; a plurality of quality value storing means, each corresponding to one of the switching planes and each coupled to the quality determining unit, for storing a corresponding quality value; pointer setting means, coupled to the plurality of quality value storing means and to the pointer, for setting the pointer to indicate the preferred switching plane in dependence on stored quality values. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification