From: nhatphuc (nhatphuc@gmail.com)
Date: Thu Dec 13 2007 - 15:24:06 ART
Hi Darren and all,
I used "override" because without it, switch only remarks untagged frame,
and leaves other frame intact. I use this together with "mls qos trust
device cisco-phone" because I think trust device have higher priority than
"mls qos cos 1 override". Am I correct?
About your configuration, can we "trust device" and "trust cos" together? I
haven't tried yet
After reading all of your answers and thinking again. I have a third option.
I repost all 3:
option 1:
mls qos trust cos
switchport priority extend cos 1
option 2:
mls qos trust device cisco-phone
mls qos cos 1 override
option 3 :
mls qos trust device cisco-phone
switchport priority extend cos 1
In fact, I took the first option from IEWB. I used to choose that, but now I
think why don't we choose the 3rd one? Isn't it better than the 1st?
Thank you
Phuc
On Dec 13, 2007 6:45 PM, Darren Johnson <dazza_johnson@yahoo.co.uk> wrote:
> Hey there! I believe your second option is wrong, you don't need the
> override and you need to trust cos. I would do it like this....
>
> mls qos trust device cisco-phone
> mls qos trust cos
> mls qos cos 1
>
> This says trust the COS value ONLY if a Cisco phone is detected via CDP,
> and
> any packets/frames without a COS value (such as those received from a PC
> on
> the native vlan) use a COS value of 1. The COS override would 'override'
> any
> COS values to 1, including COS values received from the phone!! I don't
> believe you want to do this!
>
> Dazzler
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> nhatphuc
> Sent: 12 December 2007 17:55
> To: Cisco certification
> Subject: Trust VoIP and remark Data
>
> Hi Group,
>
> With question: Ensure that VoIP traffic originating from the IP phones
> maintains its CoS value, while traffic originating from the PCs is
> remarked with a CoS of 1
>
> I see 2 ways to answer. The first seems to be better, but I don't see
> anything wrong with the second. Which one do you choose? Please explain.
>
> mls qos trust cos
> switchport priority extend cos 1
>
> and
> mls qos trust device cisco-phone
> mls qos cos 1 override
>
>
> Thank you
>
> Phuc
>
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