Computer network switching system with expandable number of ports
First Claim
1. A switching fabric circuit comprising:
- a plurality of ports each coupled to a corresponding one of a plurality of local area network (LAN) segments;
a switching link coupled to the plurality of ports for receiving requests for data transfer operations from the plurality of ports during a synchronization period, for prioritizing the requests for data transfer operations according to a high priority and a low priority during the synchronization period, and for granting requests for data transfer operations such that ports requesting data transfer operations at the high priority are guaranteed access to the switching link during the synchronization period, and such that ports requesting data transfer operations at the low priority are provided access to the switching link for a remainder of the synchronization period.
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Accused Products
Abstract
A switching fabric circuit that provides on-the-fly switching of packets, an expandable number of ports, and the interconnection of heterogeneous LAN segments. The switching fabric circuit includes a switching link that comprises a switching bus and a plurality of packet processors, wherein each packet processor is coupled between the switching bus and a LAN segment. The switching bus is a time division multiple access (TDMA) bus, and arbitration for switching bus access is distinct from arbitration for access to the ports of the switching fabric circuit. Switching bus arbitration is done according to one of two priority levels, wherein high priority requests are guaranteed access to the switching bus during a synchronization period in which the high priority requests are made. This provides for guaranteed throughput and on-the-fly switching of packets. Port arbitration may be either uniport port arbitration or multiport port arbitration. Port arbitration is characterized by the transmission of a POE mask by a source port to a destination port and by the subsequent transmission of a DPA signal by the destination port to the source port.
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Citations
16 Claims
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1. A switching fabric circuit comprising:
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a plurality of ports each coupled to a corresponding one of a plurality of local area network (LAN) segments; a switching link coupled to the plurality of ports for receiving requests for data transfer operations from the plurality of ports during a synchronization period, for prioritizing the requests for data transfer operations according to a high priority and a low priority during the synchronization period, and for granting requests for data transfer operations such that ports requesting data transfer operations at the high priority are guaranteed access to the switching link during the synchronization period, and such that ports requesting data transfer operations at the low priority are provided access to the switching link for a remainder of the synchronization period. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for transferring data between ports of a switching fabric circuit wherein a first plurality of ports is coupled to local area network (LAN) segments that transfer data at a first rate and a second plurality of ports is coupled to LAN segments that transfer data at a second rate, the method comprising the steps of:
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indicating a start of a synchronization period; requesting high priority access to a bus of switching fabric circuit by at least one of a plurality packet processors coupled to the first and second plurality of ports and the bus; granting all high priority access requests the synchronization period; requesting low priority access to the bus by at least one of the plurality of packet processors coupled to the first and second plurality of ports after all high priority access request have been granted; granting low priority access requests for the remainder of the synchronization period; and indicating a start of a new synchronization period by the central arbiter of the switching fabric circuit. - View Dependent Claims (8, 9)
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10. A method for forwarding a multiple destination packet in a switching link of a switching fabric circuit, comprising the steps of:
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monitoring a bus of the switching link by a plurality of packet processors coupled to the bus; selecting a first packet processor to transmit the multiple destination packet; indicating via the bus that the first packet processor is selected to transmit the multiple destination packet during a synchronization period; indicating by the first packet processor that the first packet processor has the multiple destination packet to transfer during the synchronization period; transmitting a port of exit mask on the bus by the first packet processor, the port of exit mask indicating which of the plurality of packet processors are destination packet processors for the multiple destination packet; indicating by the destination packet processor that the destination packet processors are ready to receive the multiple destination packet; and transmitting the multiple destination packet via the bus by the first packet processor during the synchronization period. - View Dependent Claims (11, 12, 13)
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14. A method for transferring a data packet comprising the steps of:
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requesting control of a bus by a first port to transfer the data packet during a synchronization period; granting control of the bus to the first port by a central arbiter; transferring destination information by the first port via the bus during the synchronization period, the destination information indicating a second port as a destination of the data packet; requesting control of the bus by the second port in response to receiving the destination information; granting control of the bus to the second port by the central arbiter; transferring information by the second port via bus indicating to the first port that the second port is ready to receive the data packet; and requesting access of the bus by the first port to transfer the data packet to the second port during the synchronization period. - View Dependent Claims (15, 16)
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Specification