Re: 3650 COS/DSCP to queue mapping

99999,

Can you post your configurations? I would like to see on both
interfaces what you have configured for trust and other things.

On Tue, Sep 4, 2012 at 1:46 PM, marc edwards <renorider_at_gmail.com> wrote:
> http://www.cisco.com/en/US/docs/switches/lan/catalyst3750x_3560x/software/release/12.2_58_se/configuration/guide/swqos.html#wp1023954
>
>
> Chart really says it all. What I find interested and (supporting your view)
> is the fact that DSCP-to-CoS is never used....
>
> On Tue, Sep 4, 2012 at 9:04 AM, marc edwards <renorider_at_gmail.com> wrote:
>
>> So on those thoughts.... We need to trust dscp. trusting cos throughout
>> will bypass switch from looking at dscp markings. trusting dscp will make
>> switch look into packet to see dscp markings and use mappings to convert a
>> cos value. This should hit the dscp-cos map and reference values from
>> altered config.
>>
>> Marc
>>
>>
>> On Tue, Sep 4, 2012 at 8:55 AM, marc edwards <renorider_at_gmail.com> wrote:
>>
>>> So... looks like you are tagging frames on PC NIC? Where is vlan 1 vlan 2
>>> config or are these PC's in same VLAN/subnet? Where is 'mls qos trust cos'
>>> on fa 0/2?
>>>
>>> Marc
>>>
>>>
>>> On Tue, Sep 4, 2012 at 8:46 AM, ccie99999 <ccie99999_at_gmail.com> wrote:
>>>
>>>> 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
>>>> >> >> > >>
>>>> >> >> >
>>>> >>
>>>> >>______________________________________________________________________
>>>> >> >> > >>_ Subscription information may be found at:
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>>>> >> >> > >
>>>> >> >> > >
>>>> >> >> > > Blogs and organic groups at http://www.ccie.net
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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
>>>> >> >> >
>>>> >> >> >
>>>> >>
>>>> _______________________________________________________________________
>>>> >> >> > Subscription information may be found at:
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>>>> >> >> >
>>>> >> >> >
>>>> >> >> > Blogs and organic groups at http://www.ccie.net
>>>> >> >> >
>>>> >> >> >
>>>> >>
>>>> _______________________________________________________________________
>>>> >> >> > Subscription information may be found at:
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>>>> >> >>
>>>> >> >>
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>>>> >> >>
>>>> _______________________________________________________________________
>>>> >> >> Subscription information may be found at:
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>>>> >>
>>>> >>
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>>>> >>
>>>> _______________________________________________________________________
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>>>>
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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