3560 QoS Question

[bill.greenwood]

I am dealing with a 3560G with QoS enabled and I see significant output drops on one particular interface.  This interface carries approximately 260Mbps received from several interfaces.  It appears the traffic is being dropped only from Queue 1: (snippet of sh mls qos int g1/1 stat)

 output queues dropped: 
 queue:    threshold1   threshold2   threshold3
-----------------------------------------------
 queue 0:           0           0           0 
 queue 1:   181734385           0           0 
 queue 2:           0           0           0 
 queue 3:           0           0           0 

I have tried increasing the processing of Queue 1:

srr-queue bandwidth share 1 75 25 5
srr-queue bandwidth shape 0 3  0  0

But nothing I have done seems to have any impact on the output drops from Queue 1.

I almost feel like turning QoS off altogether, but would prefer to leave QoS enabled and get the setup corrected.

Recommendations?  (And yes I have recommended the 3560G be replaced, so that is off the table)  Is my configuration correct or should I be doing something different.?

Thank you for your time.

Bill

[Joseph W. Doherty]

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Posting

Suggestions?  Well, the purpose of the shaper on that queue?  How did you try to increase processing for Q1?

Assuming the drops are due to transient bursts, and also assuming this traffic isn't latency sensitive, you can buffer tune to increase the available queue depth for this traffic.

There's a great document on these forums that explains 3560/3750 buffer tuning.  See https://supportforums.cisco.com/document/31581/egress-qos

[Jose Solano]

Hi,  

Can you get these commands and post the output?

#show mls qos maps dscp-output-q
#show mls qos queue-set

Regards,