[cisco-voip] [OSL | CCIE_Voice] DSCP to COS map question

Jonathan Charles jonvoip at gmail.com
Sun May 10 02:53:26 EDT 2009


Apologies for the lack of clarification...

The switch is a 3750-24PS

The lab is v3.

And yes, I know to trust CoS on trunks and DSCP on access ports to servers...



Jonathan

On Sat, May 9, 2009 at 9:37 PM, Michael Ciarfello
<MCiarfello at iplogic.com> wrote:
> I'm a little confused what you are asking exactly.  And I think you have the mappings backwards from what your premise statement is.
>
> Depending on switch  / router model or software the COS to DSCP map may configure 24 or 26.  If the requirement is to put signaling traffic in CS3, then use 24.  Maybe the requirement would be to put it in AF31 so use 26.
>
> Also study up on trust cos vs trust dscp and where to use each and on what piece of equipment, etc.  Some 6500 line cards have all sorts of restrctions.  QoS SRND has a great discussion of these.
>
> If you have a home lab a sniffer is a great tool to check out the markings at various places and make sure they are carrying through.
>
> ah crap, power is flickering, gotta go.
>
> ________________________________________
> From: ccie_voice-bounces at onlinestudylist.com [ccie_voice-bounces at onlinestudylist.com] On Behalf Of Jonathan Charles [jonvoip at gmail.com]
> Sent: Saturday, May 09, 2009 5:43 PM
> To: cisco-voip at puck.nether.net; ccie_voice at onlinestudylist.com
> Subject: [OSL | CCIE_Voice] DSCP to COS map question
>
> So, autoQoS adds this:
>
> mls qos map cos-dscp 0 8 16 24 32 46 48 56
>
> Yet we are advised to do this:
>
> mls qos map cos-dscp 0 8 16 26 34 46 48 56
>
> Remapping AF31 to COS 3
>
> Well the default puts CS3 into COS 3, which is what you want to do now...
>
> Am I right?
>
>
> Jonathan
>


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