Random early detect and differential packet aging flow control in switch queues

Abstract

Flow control is provided for a packet switch. An incoming packet is classified according to its priority based on predefined rules to produce a weight value based on the priority of the packet. A lifetime value associated with the packet is produced based on the weight value and the queue occupancy in a queue to which the packet is assigned. The packet is discarded if its associated lifetime value is less than or equal to a threshold value. Otherwise the packet and associated lifetime value are sent to the queue. The lifetime value is periodically changed and compared to a threshold value. The packet is removed from the queue when its lifetime value reaches the threshold value.

1 . A method of flow control in a packet switch, comprising the steps of: 
 classifying an incoming packet according to its priority based on predefined rules to produce a lifetime value associated with the packet;    sending the packet and associated lifetime value to a queue;    periodically changing the lifetime value and comparing the changed value to a threshold value; and    removing the packet from the queue based on the comparing.    
   
   
       2 . The method of  claim 1 , further comprising the steps of: 
 determining a weight value based on the priority of the packet;    determining a queue occupancy in a queue to which the packet is assigned;    producing the lifetime value based on the weight value and the queue occupancy; and    discarding the packet if its associated lifetime value is below the threshold value.    
   
   
       3 . The method of  claim 2 , wherein the discarding of the packet occurs before sending the packet and associated lifetime value to the queue.  
   
   
       4 . The method of  claim 1 , the lifetime is periodically decremented and the packed is removed from the queue when reaching the threshold value.  
   
   
       5 . A packet switch comprising: 
 a packet classification engine for classifying an incoming packet according to its priority based on predefined rules to produce a lifetime value associated with the packet;    a queue for receiving the packet and associated lifetime value;    an aging engine for periodically changing the lifetime value of the packet in the queue;    a comparator for comparing the changed value to a threshold value to remove the packet from the queue based on the comparing.    
   
   
       6 . The packet switch of  claim 5 , wherein the packet classification engine determines a weight value based on the priority of the packet; 
 and further comprising a random early detect engine for:    producing the lifetime value based on the weight value and the queue occupancy in a queue to which the packet is assigned; and    discarding the packet if its associated lifetime value is below the threshold value.