[c-nsp] 3750-x output drops

[Sigurbjörn Birkir Lárusson]

You don't necessarily need to be overrunning your Gig, it could simply be
due to small buffers, the ME3400 does this a lot with the default-queue
and the default queue-limit settings, you need to increase the default
queue-limit there to the maximum to have it drop less (it still drops, but
much much less).

I'm not familiar with the architecture of the 3750X, but perhaps that is
the case here as well...

Kind regards,
Sibbi

Þann 17.11.2011 17:26, skrifaði "Richard N. Ingram" <rich at ferlie.org>:

>On Thu, Nov 17, 2011 at 12:19:48PM +0000, marc williams wrote:
>> Can anyone shed light onto what is/goes to Queue 3 Weight 2. This is
>>where we see the drops. No QoS on this switch.
>> This switch is a:
>> WS-C3750X-48       12.2(55)SE            C3750E-IPBASEK9-M
>> 
>> 
>> show platform port-asic stats drop gigabitEthernet 4/1/4
>> 
>>   Interface Gi4/1/4 TxQueue Drop Statistics
>>     Queue 0
>>       Weight 0 Frames 0
>>       Weight 1 Frames 0
>>       Weight 2 Frames 0
>>     Queue 1
>>       Weight 0 Frames 0
>>       Weight 1 Frames 0
>>       Weight 2 Frames 0
>>     Queue 2
>>       Weight 0 Frames 0
>>       Weight 1 Frames 0
>>       Weight 2 Frames 0
>>     Queue 3
>>       Weight 0 Frames 0
>>       Weight 1 Frames 0
>>       Weight 2 Frames 438
>> 
>
>It looks like you're using a network module.  I don't have one handy to
>look at, but Queue 3 Weight 2 is probably where all your traffic is
>going.  If QOS is off, everything goes into that queue.  So if you're
>overrunning your gig. interface, those are your drops.  Other queues are
>used by the switch, even with QOS off, for things like BPDUs.  If you
>look at "show platform port-asic stats enqueue gx/x/x" you'll see some
>hits on other queues as well, but very minimal numbers compared to your
>actual user traffic.
>
>Hope that helps,
>Rich
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