Re: 3650 COS/DSCP to queue mapping

Command was like: MLS qos map dscp-cos 24 to 5

Show mls QoS dscp-cos shows it's mapped correctly
Il giorno 04/set/2012 17:35, "marc edwards" <renorider_at_gmail.com> ha
scritto:

> can you please provide command entered for dscp-cos map config?
>
> On Tue, Sep 4, 2012 at 8:31 AM, ccie99999 <ccie99999_at_gmail.com> wrote:
>
>> I did cos 3 + cos override on pc1 side and trust dscp on pc2 side.
>> I can't do a show mls qos maps now but I set up a dscp24 to cos5 mapping.
>>
>>
>>
>> On Tue, Sep 4, 2012 at 3:30 PM, marc edwards <renorider_at_gmail.com> wrote:
>>
>> > Can either of you do a sh mls qos maps? Also, please show access
>> > interfaces config. My hunch is that the dscp-cos map hasn't been
>> changed to
>> > refelect dscp 24 as cos 05. I am also curious to see if you have trusted
>> > cos or dscp on access. That will change things.
>> >
>> > Regards,
>> >
>> > Marc
>> >
>> >
>> > On Tue, Sep 4, 2012 at 8:23 AM, ccie99999 <ccie99999_at_gmail.com> wrote:
>> >
>> >> I've labbed this (cos3->dscp24->cos5) and I see I receive cos3 on the
>> >> second pc as well as dscp24.
>> >>
>> >> pc1(vlan1) - sw - pc2(vlan2)
>> >>
>> >> (I do trust cos on pc2 interface side).
>> >>
>> >> I guess it's fine I see dscp24.. don't understand why I see cos3.
>> >>
>> >> thanks
>> >>
>> >>
>> >> On Tue, Sep 4, 2012 at 12:33 PM, gp <gs4me2me_at_gmail.com> wrote:
>> >>
>> >> > Hi Joe,
>> >> >
>> >> > I tried lab what you wrote, and not have result that I expected. So I
>> >> have
>> >> > one question; in your opinion what cos value will have frame when
>> leave
>> >> > switch: cos 3 or cos 5?
>> >> >
>> >> > I had cos 3, that confuse me.
>> >> >
>> >> > Thanks
>> >> >
>> >> >
>> >> > -----Original Message-----
>> >> > From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
>> Behalf Of
>> >> > Joe
>> >> > Astorino
>> >> > Sent: Thursday, August 30, 2012 6:34 PM
>> >> > To: Anthony Sequeira
>> >> > Cc: Matt Eason; Cisco certification
>> >> > Subject: Re: 3650 COS/DSCP to queue mapping
>> >> >
>> >> > Hi Matt,
>> >> >
>> >> > Anthony answered your question simply and correctly, but I just
>> wanted
>> >> to
>> >> > add some things that helped me understand this. Like Anthony said,
>> >> > whatever
>> >> > you trust is basically how the switch determines the queue at a high
>> >> level,
>> >> > but at a deeper level there are a few different mappings going on.
>> >> Let's
>> >> > assume you trust CoS. You would have:
>> >> >
>> >> > - CoS to DSCP mapping INTERNAL to the switch
>> >> > - DSCP to CoS mapping INTERNAL to the switch
>> >> > - CoS to output queue mapping
>> >> >
>> >> > The point I am making is that even though a frame comes in with a
>> >> > particular
>> >> > CoS value, that value COULD change internally based on the internal
>> >> > COS-DSCP
>> >> > and DSCP-COS, and the frame COULD be queued based on the value
>> derived
>> >> from
>> >> > the internal mappings and not on the original value. Let's look at
>> some
>> >> > example output for a second
>> >> >
>> >> > Here are some mapping tables for cos-dscp, dscp-cos and cos-output-q
>> on
>> >> a
>> >> > 3750 switch. Note these are probably not default values because this
>> is
>> >> a
>> >> > production switch.
>> >> >
>> >> > Here is the COS to DSCP mapping:
>> >> >
>> >> > switch#sh mls qos maps cos-dscp
>> >> > Cos-dscp map:
>> >> > cos: 0 1 2 3 4 5 6 7
>> >> > --------------------------------
>> >> > dscp: 0 8 16 24 32 40 48 56
>> >> >
>> >> > Here is the DSCP to CoS mapping
>> >> >
>> >> > switch#sh mls qos map dscp-cos
>> >> > Dscp-cos map:
>> >> > d1 : d2 0 1 2 3 4 5 6 7 8 9
>> >> > ---------------------------------------
>> >> > 0 : 00 00 00 00 00 00 00 00 01 01
>> >> > 1 : 01 01 01 01 01 01 02 02 02 02
>> >> > 2 : 02 02 02 02 03 03 03 03 03 03
>> >> > 3 : 03 03 04 04 04 04 04 04 04 04
>> >> > 4 : 05 05 05 05 05 05 05 05 06 06
>> >> > 5 : 06 06 06 06 06 06 07 07 07 07
>> >> > 6 : 07 07 07 07
>> >> >
>> >> > Finally, here is the CoS to output queue mapping
>> >> >
>> >> > switch#sh mls qos map cos-output-q
>> >> > Cos-outputq-threshold map:
>> >> > cos: 0 1 2 3 4 5 6 7
>> >> > ------------------------------------
>> >> > queue-threshold: 2-1 2-1 3-1 3-1 4-1 1-1 4-1 4-1
>> >> >
>> >> >
>> >> > Let's just look at CoS 3 for example. We see that CoS 3 is mapped to
>> >> DSCP
>> >> > 24. In turn DSCP 24 is mapped right back to CoS 3 in the DSCP to COS
>> >> > mapping. In turn, CoS 3 is put into output queue 3, threshold 1.
>> >> > Fine. So in this case, it comes in as CoS 3 and is queued based on
>> CoS
>> >> 3
>> >> > because we trust CoS and because the DSCP-COS mapping is sort of
>> >> "synced".
>> >> > But...what if you went in and mucked with the DSCP-COS mapping
>> >> internally
>> >> > such that DSCP 24 was no longer mapped back to CoS 3? What if it was
>> >> > re-mapped to CoS 5 ?
>> >> >
>> >> > So you COULD have the frame come in as CoS 3 ...internally we go CoS
>> 3
>> >> > --> DSCP 24, then DSCP 24 to CoS 5 then queued based on CoS 5
>> >> >
>> >> > These are intricate details, but when you are studying for the lab, I
>> >> think
>> >> > it is important to get to the dirty details! Best of luck and I hope
>> >> this
>> >> > helps you out.
>> >> >
>> >> >
>> >> >
>> >> > On Thu, Aug 30, 2012 at 10:45 AM, Anthony Sequeira
>> >> > <terry.francona_at_gmail.com> wrote:
>> >> > > Hi Matt!
>> >> > >
>> >> > > What an AWESOME question. While the documentation does not make it
>> >> > > clear, the value that you trust on ingress, in your example, CoS,
>> is
>> >> > > the marking that is used in the appropriate default queue mapping
>> >> > > table on the egress port.
>> >> > >
>> >> > > Anthony Sequeira, CCIE, CCSI, VCP
>> >> > > http://www.stormwind.com
>> >> > > Twitter: @compsolv
>> >> > > Facebook: http://www.facebook.com/compsolv
>> >> > >
>> >> > >
>> >> > >
>> >> > > On 8/29/12 9:11 PM, "Matt Eason" <matt.d.eason_at_gmail.com> wrote:
>> >> > >
>> >> > >>Hi Guys,
>> >> > >>
>> >> > >>
>> >> > >>
>> >> > >>Can you help clarify the following. If I have a switchport
>> configured
>> >> > >>on a
>> >> > >>3560 to trust CoS inbound, that cos value is then mapped to an
>> >> > >>internal DSCP value via the COS>DSCP map. That s fine.
>> >> > >>
>> >> > >>
>> >> > >>
>> >> > >>Does this switch then determine the output queue from the original
>> CoS
>> >> > >>value or the internal DSCP value which was assigned by the switch?
>> I
>> >> > >>see both a DSCP>Output queue map and a COS>Output queue map
>> exists.
>> >> > >>
>> >> > >>
>> >> > >>
>> >> > >>Thanks,
>> >> > >>
>> >> > >>
>> >> > >>
>> >> > >>Matt
>> >> > >>
>> >> > >>
>> >> > >>Blogs and organic groups at http://www.ccie.net
>> >> > >>
>> >> >
>> >>______________________________________________________________________
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>> >> > >
>> >> > >
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>> >> > >
>> ______________________________________________________________________
>> >> > > _ Subscription information may be found at:
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>> >> > >
>> >> > >
>> >> > >
>> >> > >
>> >> > >
>> >> > >
>> >> > >
>> >> >
>> >> >
>> >> >
>> >> > --
>> >> > Regards,
>> >> >
>> >> > Joe Astorino
>> >> > CCIE #24347
>> >> > http://astorinonetworks.com
>> >> >
>> >> > "He not busy being born is busy dying" - Dylan
>> >> >
>> >> >
>> >> > Blogs and organic groups at http://www.ccie.net
>> >> >
>> >> >
>> _______________________________________________________________________
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>> >> >
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>> >>
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>>
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Received on Tue Sep 04 2012 - 15:46:46 ART