[cisco-voip] COS on Cisco 3750 - help please

[Jonathan Charles]

The RTP Stream (the actual voice traffic) is labeled COS 5 (or DSCP
EF) and the Control traffic (SCCP, MGCP, etc) is labeled COS 3 (DSCP
AF31) by the phone.

By default switches remark all DSCP (and COS) to 0 unless they are
Cisco switches set to trust the phone's DSCP settings.

So, if you have Cisco switches, the traffic should be marked correctly already.

The next step is to do something with it... and the thing to do is
creating a service policy on the router (CBWFQ).

Now, since AT&T wants it tagged as COS 1 (which I cannot, for the life
of me, figure out why), the only way to do that would be to follow
Scott's recommendation and place another service policy on the ingress
of the router to remark to COS 1.


J

On 4/20/06, Group, Russ <rgroup at harman.com> wrote:
>
>
> Hi all
>
> I'm having a problem with voice quality going over the WAN.  We use a 2801
> on each end.  Someone suggested that there might be a issue with COS.  I
> thought by default Cisco tags all voice traffic as COS 5.  AT&T is looking
> for COS 1.  Am I wrong about Cisco being tagged as COS 5?  If not, then how
> do I change the 3750 to tag the voice as COS 1 to match AT&T?
>
> Thanks
>
> Russ
>
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