need some advise on 2960x qos - egress drop packets

[kim31]

Hi guys,

i need some advise for some catalyst qos.

i have thin wireless AP connected on a cisco catalyst 2960x.

with mls qos disable, i have observed drops on the egress queue 3 weight 2.

the interface's max rx/tx is less than 6mbps, so i am suspecting bursty traffic.

i have been reading some of the related documents and articles, including the following.

• https://supportforums.cisco.com/document/31581/egress-qos

therefore, i have tried enabling mls qos and changing the buffers and threshold values using trial and error method.

• mls qos queue-set output 2 threshold 2 800 400 50 800
• mls qos queue-set output 2 threshold 4 800 400 50 800
• mls qos queue-set output 2 buffers 5 45 5 45

the cos/dscp mappings are untouched.

but i still having dropped packets in queue2, threshold 1 and 2.

there are more details in the attached file.

i do have a few queries

• am i on the right direction to minimise/troubleshoot the packet drops?
• is there any document/article to fine-tune the buffer and threshold values?
• is there any way clear the "show platform port-asic stats" counters?
• in the "show mls qos cos/dscp-output-q", all values are using threshold 1.
• there are packet drops in queue 1 weight 1 (which should be queue 2 threshold 2 in the output queue), am i correct or missing something?

thanks for any advise/replies in advance.

[Joseph W. Doherty]

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Posting

I noticed "with mls qos disable".

Are you trying these changes with QoS still disabled?  If so, I believe you may need to enable QoS to enable the commands to adjust buffers.

• am i on the right direction to minimise/troubleshoot the packet drops?

believe so

• is there any document/article to fine-tune the buffer and threshold values?

You've already found what I consider the about best of which I'm aware.

• is there any way clear the "show platform port-asic stats" counters?

Not that I'm aware of (other than a device reload)

• in the "show mls qos cos/dscp-output-q", all values are using threshold 1.
• there are packet drops in queue 1 weight 1 (which should be queue 2 threshold 2 in the output queue), am i correct or missing something?

Some of the 3750 queue stats and commands differ on starting with zero or one, might be the case here(?)

[kim31]

thanks for your input

may i know which line/output do you observed that the mls qos disabled?

i have been "playing around" with the values and settings, i might missed something.

[Joseph W. Doherty]

From your OP, i.e. "with mls qos disable"

Unclear what the situation is with your log attachment.