Internet is facing two problems simultaneously: a faster switching/routing infrastructure and guaranteed quality-of-service (QoS). Each problem can be solved independently. High performance routers can be made faster by using input-queued crossbars instead of shared memory systems. QoS can be provided by usingpacket fair queuing (PFQ) algorithm. Until now, however, the two solutions have been mutually exclusive-all ofthe work on PFQ algorithm has required that routers use output-queuing or centralize shared menory.In this paper, on the basis of CIOQ(combined input output queuing)architecture,a packt scheduling algorithm DF²Q(distributed feedback fair queeuing)is designed and implemented.The most important feature of this algorithm is the introducing of feedback mechanism.the perfomance of DF²Qis analyzed and discussed.Experimental resuts show that it can avoid internal congestion effectively and improve the efficiency of resource utilizing.