Re: MLS QOS

Thanks Narbik. We exchanged that privately. I'm wrong and all worth the
exercise for me.

Regards,

Marc

On Saturday, May 26, 2012, Narbik Kocharians wrote:

> Guys i have a lab if you guys want to see, that is FULLY tested using Ping
> commands.
>
> Carlos is NOT wrong, let me know if you are interested.
>
> On Sat, May 26, 2012 at 10:10 AM, marc edwards <renorider_at_gmail.com<javascript:_e({}, 'cvml', 'renorider_at_gmail.com');>
> > wrote:
>
>> Fair enough. Maybe I am reading into the process too much and getting
>> confused. This is the diagram I was initially referencing. That command
>> below is outlined in it as well.
>>
>>
>> http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12
>> .2_20_se/configuration/guide/swqos.html#wp1023954
>>
>>
>>
>>
>>
>> On Sat, May 26, 2012 at 9:59 AM, Carlos G Mendioroz <tron_at_huapi.ba.ar<javascript:_e({}, 'cvml', 'tron_at_huapi.ba.ar');>
>> >wrote:
>>
>> > All the red marked text (for the list sake, the between asterisk in the
>> > DSCP paragraph) applies to non IP packets. Sure, non IP packets do not
>> have
>> > DSCP to be looked at. But that's the exception, not the rule.
>> >
>> > -Carlos
>> >
>> > marc edwards @ 26/05/2012 13:55 -0300 dixit:
>> >
>> >> This is a good reference diagram for the process:
>> >>
>> >> Step 3
>> >>
>> >>
>> >>
>> >> *mls qos trust* [*cos* |*dscp* | *ip-precedence*]
>> >>
>> >>
>> >>
>> >>
>> >> Configure the port trust state.
>> >>
>> >> By default, the port is not trusted. If no keyword is specified, the
>> >> default is*dscp*.
>> >>
>> >>
>> >> The keywords have these meanings:
>> >>
>> >> *cos* Classifies an ingress packet by using the packet CoS value. For
>> >>
>> >> an untagged packet, the port default CoS value is used. The default
>> port
>> >> CoS value is 0.
>> >>
>> >> *dscp* Classifies an ingress packet by using the packet DSCP value.
>> For
>> >>
>> >> a non-IP packet, the packet CoS value is used if the packet is tagged;
>> >> for an untagged packet, the default port CoS is used. Internally, *the
>> >> switch maps the CoS value to a DSCP value by using the CoS-to-DSCP
>> map*.
>> >>
>> >> *ip-precedence* Classifies an ingress packet by using the packet
>> >>
>> >> IP-precedence value. For a non-IP packet, the packet CoS value is used
>> >> if the packet is tagged; for an untagged packet, the default port CoS
>> is
>> >> used. Internally, the switch maps the CoS value to a DSCP value by
>> using
>> >> the CoS-to-DSCP map.
>> >>
>> >>
>> >> On Sat, May 26, 2012 at 9:22 AM, Carlos G Mendioroz <tron_at_huapi.ba.ar<javascript:_e({}, 'cvml', 'tron_at_huapi.ba.ar');>
>> >> <mailto:tron_at_huapi.ba.ar <javascript:_e({}, 'cvml',
>> 'tron_at_huapi.ba.ar');>>> wrote:
>> >>
>> >> Marc,
>> >> switch don't do "correlation" in any of the meanings of that word I
>> >> know. If you trust COS, then the incoming COS value is used to
>> >> derive the internal DSCP. If you trust DSCOm then incoming DSCP
>> >> value is used instead.
>> >>
>> >> Is it hard for me to offer "evidence" of that in written form. What
>> >> you need to see it is to generate frames with different markings and
>> >> see what happen.
>> >> Medianet QoS docs may help showing it:
>> >>
>> >> http://www.cisco.com/en/US/__**docs/solutions/Enterprise/WAN_**
>> >>
>> __and_MAN/QoS_SRND_40/**QoSCampus___40.html#wp1098549<
>> http://www.cisco.com/en
>>
>> /US/__docs/solutions/Enterprise/WAN___and_MAN/QoS_SRND_40/QoSCampus___40.html<http://www.cisco.com/en/US/__docs/solutions/Enterprise/WAN___and_MAN/QoS_SRND_40/QoSCampus___40.html>
>> #wp1098549>
>> >>
>> >> <http://www.cisco.com/en/US/**docs/solutions/Enterprise/WAN_**
>> >>
>> and_MAN/QoS_SRND_40/QoSCampus_**40.html#wp1098549<
>> http://www.cisco.com/en/US/
>>
>> docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND_40/QoSCampus_40.html#wp1098549<http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND_40/QoSCampus_40.html#wp1098549>
>> >
>> >> >
>> >>
>> >> -Carlos
>> >>
>> >>
>> >> marc edwards @ 26/05/2012 12:36 -0300 dixit:
>> >>
>> >> /This is the whole point of the previous question! If you use
>> >> "trust
>> >> DSCP" then the switch will indeed use DSCP and not COS./
>> >> /
>> >>
>> >> /
>> >> Carlos, if trusting DSCP, the switch will use it's mappings to
>> >> correlate
>> >> the packet's DSCP value to the frame's COS value. Switches deal
>> >> with
>> >> frames, hense the use of COS. Please show me evidence that
>> >> supports
>> >> otherwise.
>> >>
>> >> Marc
>> >>
>> >> On Sat, May 26, 2012 at 8:25 AM, Carlos G Mendioroz
>> >> <tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar>
>> >> <mailto:tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar>>> wrote:
>> >>
>> >> marc edwards @ 26/05/2012 11:55 -0300 dixit:
>> >>
>> >> 1) doesn't matter because the switch will use it's
>> >> mappings to
>> >> take dscp
>> >> value and convert to associated cos more importantly the
>> >> mappings have
>> >> to be adjusted. either command is good but I would also
>> >> add a
>> >> 'switchpot
>> >> voice vlan XX' putting the phone into another network
>> >> and 'mls
>> >> qos trust
>> >> device cisco-phone'. These commands will put cisco
>> >> phones on another
>> >> vlan and use macros to ensure .1p is set up properly.
>> >>
>> >>
>> >> It does matter.
>> >> It is how you tell the switch to decide which marking is for
>> >> good,
>> >> and ignore the other. cos-to-dscp is only used if you
>> decide to
>> >> trust COS, otherwise the DSCP goes straight into internal
>> DSCP.
>> >> dscp-to-cos is used on output to create the L2 marking if
>> >> needed.
>> >>
>> >> But you also can use trust extend, which instructs the phone
>> >> (switch) to remark PC's packets (or should I say frames)
>> with a
>> >> given COS. That is the remarking that I was referring to.
>> >>
>> >>
>> >> 2) The Cisco phones will most likely mark both but
>> >> switch will
>> >> only use
>> >> CoS. The DSCP values are adjusted based on the internal
>> >> switch
>> >> mappings.
>> >> This mapping is not ideal left to default values and is
>> >> typically fixed
>> >> manually. I don't know why cisco just didn't make it
>> >> default.
>> >> ... This
>> >> command : 'mls qos map cos-dscp 0 8 16 24 32 46 48 56'
>> >> is used
>> >> in global
>> >> config to map EF (IP precedence 5) to the dscp value 46.
>> >>
>> >>
>> >> What do you mean by "switch will only use COS" ?? This is
>> >> the whole
>> >> point of the previous question! If you use "trust DSCP" then
>> >> the
>> >> switch will indeed use DSCP and not COS.
>> >>
>> >> The mapping is older than DSCP, at least older than any DSCP
>> >> usage
>> >> standarization, I would guess.
>> >>
>> >> -Carlos
>> >>
>> >>
>> >> You are taking the right steps for Catalyst QoS good
>> luck!
>> >>
>> >> HTH
>> >>
>> >> Marc
>> >>
>> >> On Sat, May 26, 2012 at 5:04 AM, Carlos Mendioroz
>> >> <tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar>
>> >> <mailto:tron_at_huapi.ba.ar <mailt
>> >> <mailto:Ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'Ccielab_at_groupstudy.com');>**> <mailto:Ccielab_at_groupstudy.com<javascript:_e({}, 'cvml', 'Ccielab_at_groupstudy.com');>
>> >> <mailto:Ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'Ccielab_at_groupstudy.com');>**>__>
>> >> <mailto:Ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'Ccielab_at_groupstudy.com');> <mailto:Ccielab_at_groupstudy.com<javascript:_e({}, 'cvml', 'Ccielab_at_groupstudy.com');>
>> **>
>> >> <mailto:Ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'Ccielab_at_groupstudy.com');>
>> >> <mailto:Ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'Ccielab_at_groupstudy.com');>**>__>__>"
>> >>
>> >> <ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'ccielab_at_groupstudy.com');> <mailto:ccielab_at_groupstudy.com<javascript:_e({}, 'cvml', 'ccielab_at_groupstudy.com');>
>> **>
>> >> <mailto:ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'ccielab_at_groupstudy.com');> <mailto:ccielab_at_groupstudy.com<javascript:_e({}, 'cvml', 'ccielab_at_groupstudy.com');>
>> **
>> >> >__>
>> >> <mailto:ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'ccielab_at_groupstudy.com');> <mailto:ccielab_at_groupstudy.com<javascript:_e({}, 'cvml', 'ccielab_at_groupstudy.com');>
>> **>
>> >> <mailto:ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'ccielab_at_groupstudy.com');>
>> >> <mailto:ccielab_at_groupstudy.com <javascript:_e({}, 'cvml',
>> 'ccielab_at_groupstudy.com');>**>__>__>>
>> >>
>> >> Sent: Sat, 26 May 2012, 05:36:38 GMT+00:00
>> >> Subject: MLS QOS
>> >>
>> >> Hi all,
>> >>
>> >> I got the below questions to clarify.
>> >>
>> >> 1) When a cisco VoIP phone is connected to a
>> >> switchport,
>> >> which is
>> >> better?
>> >> mls qos trust dscp or mls qos trust cos?
>> >>
>> >> 2) The cisco phone will mark cos or dscp value or
>> >> both? If
>> >> mls qos trust
>> >> cos is use, must i map the cos 5 to dscp 46
>> manually?
>> >>
>> >> Regards
>> >> Vincent Tay
>> >>
>> >>
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>> >>
>> >>
>> >>
>> >>
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>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> --
>> >> Carlos G Mendioroz <tron_at_huapi.ba.ar <javascript:_e({},
>> 'cvml', 'tron_at_huapi.ba.ar');>
>> >> <mailto:tron_at_huapi.ba.ar <javascript:_e({}, 'cvml',
>> 'tron_at_huapi.ba.ar');>> <mailto:tron_at_huapi.ba.ar <javascript:_e({},
>> 'cvml', 'tron_at_huapi.ba.ar');>
>> >>
>> >> <mailto:tron_at_huapi.ba.ar <javascript:_e({}, 'cvml',
>> 'tron_at_huapi.ba.ar');>>>> LW7
>> >> EQI Argentina
>> >>
>> >>
>> >>
>> >> --
>> >> Carlos G Mendioroz <tron_at_huapi.ba.ar <javascript:_e({}, 'cvml',
>> 'tron_at_huapi.ba.ar');> <mailto:tron_at_huapi.ba.ar <javascript:_e({},
>> 'cvml', 'tron_at_huapi.ba.ar');>>> LW7
>> >> EQI Argentina
>> >>
>> >>
>> >>
>> > --
>> > Carlos G Mendioroz <tron_at_huapi.ba.ar <javascript:_e({}, 'cvml',
>> 'tron_at_huapi.ba.ar');>> LW7 EQI Argentina
>>
>>
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>
>
> --
> *Narbik Kocharians
> *CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> *www.MicronicsTraining.com* <http://www.micronicstraining.com/>
> Sr. Technical Instructor
> YES! We take Cisco Learning Credits!
> A Cisco Learning Partner

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Received on Sat May 26 2012 - 12:30:17 ART