Systems and methods for limiting low priority traffic from blocking high priority traffic

Abstract

A method for processing high priority packets and low priority packets in a network device includes performing arbitration on high priority packets until no high priority packets remain. Arbitration then is enabled on low priority packets. A packet size associated with the selected low priority packet is compared with a programmable threshold. Low priority packets are excluded from subsequent arbitration for a programmable duration when the packet size exceeds the programmable threshold.

1 - 23 . (canceled) 
     
     
         24 . A method comprising:
 comparing a size of a low priority data unit to a threshold;   selecting a high priority data unit from one or more high priority queues when the size of the low priority data unit is less than the threshold; and   preventing selection of a different low priority data unit from one or more low priority queues for a programmable duration when the size of the low priority data unit is greater than or equal to the threshold.   
     
     
         25 . The method of claim  23 , where preventing the selection of the different low priority data unit includes preventing selection of the different low priority data unit from a low priority queue of the one or more low priority queues from which the low priority data unit was selected. 
     
     
         26 . The method of  claim 24 , where preventing selection of the different low priority data unit includes preventing selection of the different low priority data unit from all low priority queues of the one or more low priority queues. 
     
     
         27 . The method of  claim 24 , where the programmable duration is related to a length of time for a processor to process the low priority data unit. 
     
     
         28 . The method of  claim 24 , where the programmable duration is related to a latency of flow control logic that monitors a size of a plurality of high priority data units and a size of a plurality of low priority data units. 
     
     
         29 . The method of  claim 24 , where comparing the size of the low priority data unit to the threshold includes:
 comparing the size of the low priority data unit to a particular threshold associated with a queue with the low priority data unit.   
     
     
         30 . The method of  claim 24 , where the programmable delay is associated with a particular low priority queue of the one or more low priority queues. 
     
     
         31 . A system comprising:
 an arbiter to:
 compare a size of a dequeued low priority data unit with a threshold; 
 dequeue a high priority data unit from at least one high priority queue when the size of the dequeued low priority data unit is less than the threshold; and 
 prevent dequeuing of a different low priority data unit from at least one low priority queue of a plurality of low priority data queues for a programmable duration when the size of the dequeued low priority data unit is greater than or equal to the threshold. 
   
     
     
         32 . The system of  claim 31 , where the arbiter is further configured to prevent dequeuing of the different low priority data unit from a low data priority queue of the plurality of low data priority queues from which the dequeued low priority data unit was dequeued when the size of the dequeued low priority data unit is greater than or equal to the threshold. 
     
     
         33 . The system of  claim 31 , where the arbiter is further configured to prevent dequeueing of the different low priority data queue from all low priority queues of the plurality of low priority data queues when the size of the dequeued low priority data unit is greater than or equal to the threshold. 
     
     
         34 . The system of  claim 31 , further comprising:
 a flow control device having an associated latency, the flow control device configured to:
 monitor a size of data units output by a head queue, 
 compare the size of the data units to a second threshold, and 
 stop flow of the data units if the size of the data units exceeds the threshold. 
   
     
     
         35 . The system of  claim 34 , where the programmable duration is related to the associated latency. 
     
     
         36 . The system of  claim 31 , where the arbiter includes a high priority arbiter and a low priority arbiter. 
     
     
         37 . The system of  claim 31 , where, when comparing the size of the low priority data unit to the threshold, the arbiter is further configured to:
 compare the size of the low priority data unit to a threshold associated with a queue with the low priority data unit.   
     
     
         38 . The system of  claim 31 , where the programmable delay is associated with a particular low priority queue of the plurality of low priority queues. 
     
     
         39 . A system comprising:
 a comparison processor to compare a size of a data unit with a threshold and to output one or more control signals based on the comparison,   a delay processor to produce one or more delay signals in response to the one or more control signals from the comparison element, and   a mask processor to prevent a selection of a different data unit from one or more low priority queues for a duration defined by the one or more delay signals.   
     
     
         40 . The system of  claim 39 , where the delay processor is further configured to produce the one or more delay signals when the size of the data unit is greater than or equal to the threshold. 
     
     
         41 . The system of  claim 39 , where the duration is based on a latency of flow control logic that monitors a size of a plurality of high priority data units and a size of a plurality of low priority data units. 
     
     
         42 . The system of  claim 39 , where the duration is associated with a particular low priority queue of the one or more low priority queues. 
     
     
         43 . The system of  claim 39 , where the one or more low priority queues includes a plurality of low priority queues and where the mask register is to prevent the arbiter from selecting a different data unit from the plurality of the one or more low priority queues for the duration defined by the one or more delay signals.