Re: QoS quiz

Just a small question - to really protect voice, should you specify the RTP
payload types so you are not potentially including video in the class?

Cheers,
Adam

On Sat, Jun 18, 2011 at 9:26 AM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:

> I know it is the same. This is the configuration that I would have done,
> and that I guess many do. But I was surprised when I realized that it does
> not work, or at least, it does not work as I thought it would.
>
> Hence the quiz. Either I'm confused (more than likely :) or there is no
> easy way to configure what I described. And it does not sound a weird
> requirement...
>
> To really protect the voip flows you have to set the priority class in
> the parent policy. This will side step the shape buffer.
> On the other hand, you will be overrunning your CIR!
> Is there any way to have priority + shape work in synch ?
> Some kind of shape adapt to "rest of" bandwidth...
>
> -Carlos
>
> David Prall @ 17/06/2011 20:07 -0300 dixit:
>
> It is the same as your configuration. I didn't include the parent because
>> you already had that covered. I used priority percent instead of a
>> bandwidth
>> value, because then I can use it across multiple shaper values with only
>> needing to change one parameter for different configurations.
>>
>> 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 6:35 PM
>>> To: David Prall
>>> Cc: 'Cisco certification'
>>> Subject: Re: QoS quiz
>>>
>>> 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:
>>>>>>> http://www.groupstudy.com/**list/CCIELab.html<http://www.groupstudy.com/list/CCIELab.html>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>>>>>
>>>> --
>>> 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:
>>> http://www.groupstudy.com/**list/CCIELab.html<http://www.groupstudy.com/list/CCIELab.html>
>>>
>>>
>>>
>>>
>>>
>>
>>
> --
> 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: http://www.groupstudy.com/**
> list/CCIELab.html <http://www.groupstudy.com/list/CCIELab.html>

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Received on Sat Jun 18 2011 - 16:04:34 ART