qos input-queue

Answered Question
Mar 17th, 2010
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hello,


had a question regarding the configuration of the ingree-queue on a 3560. Here is the configuration from my switch




mls qos srr-queue input threshold 1 8 16

mls qos srr-queue input threshold 2 34 66


mls qos srr-queue input dscp-map queue 1 threshold 3  0 1 2 3 4 5 6 7

mls qos srr-queue input dscp-map queue 1 threshold 3  32

mls qos srr-queue input dscp-map queue 2 threshold 1  16 17 18 19 20 21 22 23

mls qos srr-queue input dscp-map queue 2 threshold 2  33 34 35 36 37 38 39 48

mls qos srr-queue input dscp-map queue 2 threshold 2  49 50 51 52 53 54 55 56

mls qos srr-queue input dscp-map queue 2 threshold 2  57 58 59 60 61 62 63

mls qos srr-queue input dscp-map queue 2 threshold 3  24 25 26 27 28 29 30 31

mls qos srr-queue input dscp-map queue 2 threshold 3  40 41 42 43 44 45 46 47


i believe this is the default configuration generated by auto-qos. here is the output from a show mls qos input-queue command



Queue     :       1       2

----------------------------------------------

buffers   :         67      33

bandwidth :      90      10

priority  :          0      10

threshold1:       8      34

threshold2:      16      66


so my question is if i have only two threshold configured for each queue, how come the switch put certain dscp values in queue 2 threshold 3. check the highlighted lines. its really confusing me.


thanks.

Correct Answer by Aaron Harrison about 7 years 4 months ago

Hi


You have 3 thresholds :-)


Two configurable; and one implicit one - the end of the queue.


So for queue 1 in your output -


Thresh 1 - 8

Thresh 2 - 16

Thresh 3 - 100% of available buffer space.


Regards


Aaron


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Correct Answer
Aaron Harrison Wed, 03/17/2010 - 06:43
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Hi


You have 3 thresholds :-)


Two configurable; and one implicit one - the end of the queue.


So for queue 1 in your output -


Thresh 1 - 8

Thresh 2 - 16

Thresh 3 - 100% of available buffer space.


Regards


Aaron


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Aaron Harrison Wed, 03/17/2010 - 07:28
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Well - probably clears some of it.


There'll be more


I like to think I know a thing or two but they don't make it simple!

vasanth77 Thu, 01/28/2016 - 03:49
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Hi,

     Is there any difference in  Qos configuration of 37xx series switches  and 45XX ,65xx?

can anyone clarify ?

For Qos what parameters are the most important?


Joseph W. Doherty Thu, 01/28/2016 - 05:04
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Posting

Yes, QoS configurations differ, as often do the supported QoS features.  Additionally, with the chassis devices, QoS features may vary based on installed line card(s) and/or supervisor (and sometimes QoS version too).

As to which QoS parameters are most important, that would be an "it depends" answer.

francisco_1 Wed, 03/17/2010 - 07:20
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aqdas,


it is very easy to get confused with Qos.


The ingress queue has a total of 4 queues. The first 2 are used internally by the system for inter-stack communication and priority packets originated from the CPU. Out of the 4 queues, only 2 may be configured. One queue is priority by default, which has bigger priority weight. The other qeueue is the normal queue used of rtraffic that is considered to be best effort. within each of the queues are 3 weighted tail drop threasholds with that allow for 2 threasholds to be configured and the third fixed at 100%.

Francisco

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