Re: QoS question

Carlos,

Below is the policy-map I used :

policy-map QoS_Marking
    class Critical_Traffic
        set ip dscp 26
        exit
    class DC_Traffic
        set ip dscp 18
        exit
    class class-default
        set ip dscp 0

I applied this inbound on an user/phone interface which looks like this :
switchport access vlan YY
switchport voice vlan XX
mls qos trust cos
mls qos trust device cisco-phone
service-policy input QoS_Marking

Capturing the traffic on the uplink port I saw that voice packets from the
port configured like above were marked DSCP EF so the trust device
cisco-phone command has priority over the policy-map or it certainly looks
like it has :)

Best Regards,

Adrian

On Fri, Apr 9, 2010 at 4:46 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar> wrote:

> Adrian,
> to better understand your example, you should post the policy too.
>
> You say "the phone DSCP EF marking is not overwritten by the policy-map"
> but I would expect it to, given that the policy actually calls for
> a remark.
>
> I don't ubderstand your last paragraph. The PC marking, if any, will
> be cleared (reset to 0) by the phone AFAIK. Remember that there's always
> a mark at L3, there's no way to tell apart a "marked as 0" or
> unmarked, if that term is ever used.
>
> -Carlos
> Firm believer that confusion is the beginning of wisdom :)
>
>
> Lazar Adrian @ 9/04/2010 9:10 -0300 dixit:
> > Hi Carlos,
> >
> > Thanks for your prompt answer.
> > As I really needed to know what is the exact behavior in this case I have
> > tested it using a 3560 switch and a cisco phone.
> > The original IOS on the switch (1-2 years old) didn't even permit the
> > service-policy input command on the interface at the same time with "mls
> qos
> > trust device cisco-phone".After I upgraded to the latest 3560 IOS,
> > 12.2(53)SE, the behavior changed dramatically. Now I was permitted to put
> > the two commands on the same interface and after capturing some traffic
> it
> > seems the phone DSCP EF marking is not overwritten by the policy-map I
> > defined (which was not marking the voice packets with DSCP EF).
> > To summarize, below are the commands I used to configure the interface:
> >
> > mls qos trust cos
> > mls qos trust device cisco-phone
> > service-policy input QoS_Marking
> >
> > As this was a user/phone port those commands had the effect of letting
> the
> > DSCP EF mark of the phone to go through untouched by the policy and mark
> the
> > user traffic according to the policy (seemed that "mls qos trust cos "
> > command didn't apply to user traffic ).
> >
> > Best Regards,
> >
> > Adrian
> >
> > On Thu, Apr 8, 2010 at 12:52 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar
> >wrote:
> >
> >> Adrian,
> >> ip traffic is always marked with some code, that should give you a clue.
> >> But if it does not, then it depends on the logic of the policy, but
> >> you can remark if you will. In your terms, the policy has precedence.
> >>
> >> "mls qos trust device" only disables the wiping of the incoming mark.
> >>
> >> It's a litle more complicated than that in fact. You need to have
> >> "mls qos trust dscp" in place, and that initializes the internal QoS
> >> marking to that of the incoming IP dscp. Then if "trust device" is
> >> added, the initialization is replaced with 0 if the connected device
> >> is not a cisco phone. Then comes your policy to change whatever, and
> >> last and option to leave the initial marking alone when sending.
> >> To top it, this is architecture dependent.
> >>
> >> HTH,
> >> -Carlos
> >>
> >> Lazar Adrian @ 8/04/2010 6:29 -0300 dixit:
> >>> Hi guys,
> >>>
> >>> I have a simple QoS implementation with one policy-map marking the
> >> traffic
> >>> inbound coming from a user or IP phone (I have a general port config,
> so
> >>> same port config no matter if a PC or phone connects to it).
> >>> Now, my question is related to the precedence of "mls qos trust device
> >>> cisco-phone" and "service-policy QoS_Marking inbound" commands. What I
> >> want
> >>> to know and I haven't found this information anywhere is, if my phone
> >> sends
> >>> DSCP EF marked traffic will the policy-map mark it down ? So the matter
> >>> resumes to what command has precedence over the other.
> >>>
> >>> Thank you,
> >>>
> >>> Adrian
> >>>
> >>> PS: Disregard the previous mail, I accidentally hit the send button too
> >>> early :)
> >>>
> >>>
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> >>>
> >> --
> >> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
> >
> >
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> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina

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Received on Fri Apr 09 2010 - 18:43:15 ART