Re: QoS - srr-queue share and shape together

Keller thanks for info.

Please look below calculation it is right?

Int fa0/20 = 100Mb
mls qos
interface FastEthernet0/20
 srr-queue bandwidth share 1 1 7 3
 srr-queue bandwidth shape 4 4 0 0
 mls qos trust dscp
          Q1 Q2 Q3 Q4
shape 4 4 0 0
Q1 = 1/4 of full bandwidth(100Mb) = 25Mb -> 1/4 * 100Mb = 25Mb
Q2 = 1/4 of full bandwidth(100Mb) = 25Mb -> 1/4 * 100Mb = 25Mb
Q3 = 0 - it means this queue will be serviced by shared mode
Q4 = 0 - it means this queue will be serviced by shared mode
         Q1 Q2 Q3 Q4
share 1 1 7 3
Q1 = 1 and Q2 = 1 configured but shape have Q1 = 4 and Q2 = 4.
It means those queues will shape do.
We don't use them in below bandwidth calulacion.
But remember that bandwidth of interface for this queues
isn't 100Mb but (100Mb-(Q1+Q2))
Q1 = 1 -> 0
Q2 = 1 -> 0
Q3 = 7 -> 7/(0+0+7+3)=7/10 of remaining bandwidth(100Mb-(Q1+Q2))
                                   7/10 of remaining
bandwidth(100Mb-(25Mb+25Mb))
                                   7/10*50Mb=35Mb
Q4 = 3 -> 3/(0+0+7+3)=3/10 of remaining bandwidth(100Mb-(Q1+Q2))
                                   3/10 of remaining
bandwidth(100Mb-(25Mb+25Mb))
                                   3/10*50Mb=15Mb
Summary
Q1 = 25Mb
Q2 = 25Mb
Q3 = 35Mb
Q4 = 15Mb
     = 100Mb

On 5/3/13, Keller Giacomarro <keller.g_at_gmail.com> wrote:
> 'shape' is defined in absolute terms, while 'share' is based on relative
> weights. The bandwidth reserved is the inverse of the 'shape' value set.
> For instance, a setting of 2 would yield 1/2 of the interface bandwidth
> reserved for that queue.
>
> Also note that setting a 'shape' value for a queue will cause the 'shared'
> setting to be ignored entirely.
>
> I'm pretty sure your config is not doing what you think its doing.
>
> Keller Giacomarro
> keller.g_at_gmail.com
>
>
> On Fri, May 3, 2013 at 3:38 PM, _ _ <krzysiek.zalewski_at_gmail.com> wrote:
>
>> Hi. Please look below calculation, it is ok?
>>
>> interface FastEthernet0/20
>> srr-queue bandwidth share 1 1 7 3
>> srr-queue bandwidth shape 4 4 0 0
>> mls qos trust dscp
>>
>> Q1 Q2 Q3 Q4
>> shape 4 4 0 0
>> share 1 1 7 3
>> = 4 4 7 3
>>
>> Q1 = 4 -> 4/(4+4+7+3)=4/18 of full bandwidth(100Mb) = 22,22Mb ->
>> 4/18*100Mb=22,22Mb
>> Q2 = 4 -> 4/(4+4+7+3)=4/18 of full bandwidth(100Mb) = 22,22Mb ->
>> 4/18*100Mb=22,22Mb
>> Q3 = 7 -> 7/(4+4+7+3)=7/18 of full bandwidth(100Mb) = 38,88Mb ->
>> 7/18*100Mb=38,88Mb
>> Q4 = 3 -> 3/(4+4+7+3)=3/18 of full bandwidth(100Mb) = 16,66Mb ->
>> 3/18*100Mb=16,66Mb
>>
>> =99,98Mb
>> When Q3 and Q4 will have free bandwidth, can exchange it when they need.
>> If Q4 is empty = 0 -> Q3 will have 38,88Mb+16,66Mb=55,54Mb
>> If Q3 is empty = 0 -> Q4 will have 16,66Mb+38,88Mb=55,54Mb
>> --
>> Krzysiek
>>
>>
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-- 
Krzysiek
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