3750 Threshold 3 Parameters

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Feb 11th, 2008
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The 3rd threshold on each output queue of a 3750 is documented as being non-configurable and representing 100% of the queue buffer. Is this threshold actually represented by the 'maximum' parameter in the queue-set, which actually is configurable? If not, what are the Thresh3 settings? (i.e. 100 100 100 100, something else?)

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owillins Fri, 02/15/2008 - 11:39
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If you want to change the buffers/thresholds, you can do that by modifying the Queue-set parameters for the particular interfaces. Please note that the Queue-sets effect _all_ the ports belonging to that queue-set. However, if you just intended to shape/rate limit a particular queue on a port, that can be done individually for a port.

jhaverkos Tue, 02/19/2008 - 05:02
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There is no explicitly specified place to modify threshold 3 in the 3750 queue-set and documentation suggests that threshold 3 can not be changed. So my question is, what are threshold 3's parameters?

paolo bevilacqua Fri, 02/15/2008 - 11:46
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Please satisfy my curiosity, are you asking this question because you've meet a real problem in QoS, or just trying to understand the working of the switch ?

EDIT: I see from other thread that you got a drops problem, so forget my question. Unfortunately I don't know the answer to your.

jhaverkos Tue, 02/19/2008 - 05:15
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Yes, we do have drops. I believe drops are expected when policies are applied. Your curiosity is correct, I want to know how the switch works so I understand the how/when these drops occur. I am really looking for an answer as to how the Threshold 3 parms are set so we can optimize our QoS policies. Note again, the 3750 queue-set does not explicitly show a Threshold 3. I am looking for a definition of the buffer allocation and drop thresholds used for Threshold 3.


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