Alcatel

Alcatel Internetworking, Inc.

Xylan Corporation

Drew Bertagna

Anees Narsinh

A queue scheduling method and apparatus for a queuing structure including a plurality of queues at different priorities and having different bandwidth privileges competing for the bandwidth of an output. The method selects a queue at the current priority, having data for release to the output and having available bandwidth to release data to the output. If there are a plurality of such queues, round-robin ordering determines which queue in the plurality is selected. The apparatus includes a plurality of bit masks representing the status in relation to a queue state variable of the different queues, which masks are combined in a bit-wise AND operation to determine which queues are selectable for releasing data to the output.

Qualified priority queue scheduler

A data communication switch receives packets having first priorities, generates second priorities as a function of the first priorities, prioritizes selected ones of the plurality of packets as a function of the second priorities and transmits the plurality of packets having the second priorities. The first priorities may be inbound Std. 802.1Q tag priorities and the second priorities may be regenerated Std. 802.1Q tag priorities. Priority selection may be communicated in the switch through the expedient of packet marking. Marks may be instantiated in the packets prior to subjecting the packets to prioritization on the switch and removed from the packets prior to transmitting the packets from the switch. The switch may be arranged to prioritize selected ones of 802.1Q-complaint tagged packets based on a tag priority while preserving tag priority signaling for all such tagged packets.

Selectable prioritization for data communication switch

Priority processing for a data communication switch, such as a LAN switch supporting source-learned bridging, in which a priority value for application to an outbound tagged packet is determined based on an inbound tag priority and a plurality of other values, such as an inbound tag VLAN and receiving port identifier. The plurality of other values may be initially resolved to a virtual trunk identifier, which virtual trunk identifier may be applied with the inbound tag priority to determine the outbound tag priority. The virtual trunk identifier may be resolved by reducing the plurality of other values to a smaller-bit value and using the smaller-bit value in a table look-up.

Priority remapping for data communication switch

A protocol translation hardware assist for resolving protocol incompatibilities in a multi-protocol switching environment. Discrete information units are transferred seamlessly from inputs to disparate protocol outputs by writing inbound discrete information units into selected address spaces in allocated buffers in a transfer queue in a manner which accounts for protocol format differences while allowing for straightforward dequeueing. The hardware assist fragments inbound discrete information units into multiple outbound units and creates offsets indicated by destination protocol requirements. A bypass check may be implemented to avoid subjecting to the fragmentation inquiry discrete information units for which it can be inferred a priori that fragmentation is not required.

Translation hardware assist for data communication switch

A data transfer system efficiently allocates contiguous address spaces in a destination storage area to packets by maintaining a plurality of lists from which different amounts of contiguous address spaces are allocated. List selection is made based on known or presumed packet characteristics. By arranging different lists to supply contiguous address spaces in different amounts based on packet-specific characteristics, over-allocation of address space may be reduced considerably while contiguous address space is guaranteed on a continuous basis.

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Oak Park, CA, United States of America

Drew Bertagna