Re: QoS quiz

Cool! One more thing I noticed in your prev example wasbandwidth
statement missing under interface fa 0/0. This one should align with
your shaping rate. This one and the max-available-bw is a base line for
bandwidth allocation inside MQC queues. It is also a way many reporting
tools pull interfaces for bandwidth utilization reports.

HTH
A.

On 6/21/2011 8:02 AM, Carlos G Mendioroz wrote:
> Just to be sure, and because my previous test was in an old platform
> (2600Xm running 12.4.9T), I just tested it again with 15.1.1T on
> a 2811.
>
> policy-map child
> class voice
> priority 500
> set dscp ef
> class class-default
> set dscp default
> bandwidth remaining percent 100
> policy-map parent
> class class-default
> shape average 1000000
> service-policy child
>
> And now it works. Cool.
> On the other hand, I would have thought that this worked before, back
> in the time when 15.0 (or 12.4.20) did not exist.
> Oh well, seems nothing should be taked for granted.
>
> -Carlos
>
> Alexei Monastyrnyi @ 20/06/2011 09:23 -0300 dixit:
>> Well, according to the docs shaping uses FIFO by default which can be
>> changed to either WFQ or any queuing under nested service-policy.
>>
>> http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6558/white_paper_c11-481499.html
>>
>>
>> Default Queuing Implementation for the Shape Feature
>>
>> When you configure the shape command in a class, the default queuing
>> behavior for the shape queue is FIFO instead of WFQ. You can
>> configure the bandwidth, fair-queue, or service-policy commands in
>> shape class to achieve different queuing behaviors.
>>
>> I can test it in our prof of concept lab but I am quite sure it will
>> play out exactly that way or else it would be quite a miss by Cisco :-)
>>
>> Cheers,
>> A.
>>
>>
>>
>> On 6/20/2011 9:57 PM, Carlos G Mendioroz wrote:
>>> Alexei,
>>> what you describe is what would happen with only one policy at the
>>> port,
>>> which is not the case. When you have parent/child, you basically
>>> "create" a serial setup where the parent output becomes the child
>>> input.
>>>
>>> The parent is doing shapping for ALL traffic without classification.
>>> And it's a FIFO queue. So when it kicks in (rate above shape rate) you
>>> start delaying all traffic.
>>>
>>> Don't take my word, test it. May be there's some way to make it work,
>>> but I don't know it!
>>>
>>> -Carlos
>>>
>>> Alexei Monastyrnyi @ 20/06/2011 05:23 -0300 dixit:
>>>> Carlos
>>>> I don't think this is the case.
>>>>
>>>> In case of shaping buffer not empty the packet which is about to
>>>> egress would go into scheduler and based on its marking it would be
>>>> placed into the right queue, in you case in either LLQ or the
>>>> class-default one. Now if it is a voice packet scheduled for LLQ it
>>>> will egress as soon as it can regardless of class-default queue
>>>> being full or not (well, up to the priority XYZ value, where it
>>>> will be policed, and we are not taking serialization into account
>>>> here as all is happening at FE speed).
>>>>
>>>> So I reckon your voice traffic should be just fine. I may be
>>>> missing something so please correct me if I am wring.
>>>>
>>>> Cheers
>>>> A.
>>>>
>>>>
>>>> On 6/18/2011 8:35 AM, Carlos G Mendioroz wrote:
>>>>> The problem with this configuration, which AFAIK is "by the book",
>>>>> is that it does not protect the Voip stream.
>>>>>
>>>>> If you have a data stream that is going over your shape rate,
>>>>> the shape buffer will be full and your voip traffic has to cross it!
>>>>> (Read, you will have jitter at best, lost packets more than likely)
>>>>>
>>>>> -Carlos
>>>>>
>>>>> David Prall @ 17/06/2011 18:49 -0300 dixit:
>>>>>> Carlos,
>>>>>> So I would do:
>>>>>> Class-map match-all voice
>>>>>> Match protocol rtp
>>>>>> Match dscp ef
>>>>>> Policy-map child
>>>>>> Class voice
>>>>>> Priority percent 25
>>>>>> Class class-default
>>>>>> Bandwidth remaining percent 100
>>>>>> Set dscp 0
>>>>>>
>>>>>> David
>>>>>>
>>>>>> --
>>>>>> http://dcp.dcptech.com
>>>>>>
>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: Carlos G Mendioroz [mailto:tron_at_huapi.ba.ar]
>>>>>>> Sent: Friday, June 17, 2011 5:40 PM
>>>>>>> To: David Prall
>>>>>>> Cc: 'Cisco certification'
>>>>>>> Subject: Re: QoS quiz
>>>>>>>
>>>>>>> Right.
>>>>>>> This is *one* thing I left out. All traffic should be marked.
>>>>>>> -Carlos
>>>>>>>
>>>>>>> David Prall @ 17/06/2011 18:31 -0300 dixit:
>>>>>>>> You are matching on RTP, is all RTP already marked EF? You are
>>>>>>>> using
>>>>>>> shape
>>>>>>>> average to provide artificial back-pressure at 2Mbps. You have
>>>>>>> provided for
>>>>>>>> 500Kbps within the 2Mbps so you will be fine as long as the
>>>>>>>> carrier
>>>>>>> is
>>>>>>>> providing priority for the RTP traffic, if they are providing
>>>>>>> priority for
>>>>>>>> EF then you need to confirm that the application is setting EF or
>>>>>>> remark the
>>>>>>>> traffic on your own to EF. You also need to confirm that the
>>>>>>>> traffic
>>>>>>> that is
>>>>>>>> not RTP, is not marked EF, otherwise the SP will put it into
>>>>>>>> their EF
>>>>>>> queue
>>>>>>>> along with your RTP EF traffic, so remarking the class-default
>>>>>>>> to 0
>>>>>>> may help
>>>>>>>> here.
>>>>>>>>
>>>>>>>> David
>>>>>>>>
>>>>>>>> --
>>>>>>>> http://dcp.dcptech.com
>>>>>>>>
>>>>>>>>> -----Original Message-----
>>>>>>>>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
>>>>>>>>> Behalf
>>>>>>> Of
>>>>>>>>> Carlos G Mendioroz
>>>>>>>>> Sent: Friday, June 17, 2011 5:05 PM
>>>>>>>>> To: Cisco certification
>>>>>>>>> Subject: QoS quiz
>>>>>>>>>
>>>>>>>>> Easy one, I would think.
>>>>>>>>>
>>>>>>>>> Say you have a wan link provided over metro (i.e. access rate is
>>>>>>> well
>>>>>>>>> over your contracted BW) and you want to apply QoS to protect
>>>>>>>>> your
>>>>>>>>> Voip.
>>>>>>>>>
>>>>>>>>> You have 2Mbps contract, 25% limit on EF marked traffic.
>>>>>>>>>
>>>>>>>>> Will this config do the right thing (i.e. protect your voip
>>>>>>>>> traffic
>>>>>>>>> from jitter caused by your data) ?
>>>>>>>>>
>>>>>>>>> class-map voice
>>>>>>>>> match protocol rtp
>>>>>>>>>
>>>>>>>>> policy-map child
>>>>>>>>> class voice
>>>>>>>>> priority 500
>>>>>>>>> class class-default
>>>>>>>>> bandwidth remaining percent 100
>>>>>>>>>
>>>>>>>>> policy-map parent
>>>>>>>>> class class-default
>>>>>>>>> shape average 2000000
>>>>>>>>> service-policy child
>>>>>>>>>
>>>>>>>>> inferface fastEthernet0/0
>>>>>>>>> service-policy output parent
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>>>>>
>>>>>>>>>
>>>>>>> _______________________________________________________________________
>>>>>>>
>>>>>>>>> Subscription information may be found at:
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>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>> --
>>>>>>> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
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Received on Tue Jun 21 2011 - 08:21:12 ART